diff --git a/testsuite/tests/create_project/test.py b/testsuite/tests/create_project/test.py
index e58cb7ddf..4a478fdff 100644
--- a/testsuite/tests/create_project/test.py
+++ b/testsuite/tests/create_project/test.py
@@ -3,6 +3,9 @@ Test that the "create-project.py" script creates a valid Langkit project by
 generating it and building it.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 import subprocess
 import sys
@@ -23,4 +26,4 @@ manage_py = os.path.join('mylang', 'manage.py')
 python(create_project_py, 'Mylang')
 python(manage_py, '-vnone', 'make')
 
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/grammar/invalid_list/test.out b/testsuite/tests/grammar/invalid_list/test.out
index 82b86e51a..384239295 100644
--- a/testsuite/tests/grammar/invalid_list/test.out
+++ b/testsuite/tests/grammar/invalid_list/test.out
@@ -1,5 +1,5 @@
-File "test.py", line 30, In definition of grammar rule main_rule
+File "test.py", line 33, In definition of grammar rule main_rule
     Error: List parsers only accept subparsers that yield AST nodes (TokenType provided here)
-File "test.py", line 39, In definition of grammar rule main_rule
+File "test.py", line 42, In definition of grammar rule main_rule
     Error: Invalid list type for List parser: ListNode. Not a list type
 Done
diff --git a/testsuite/tests/grammar/invalid_list/test.py b/testsuite/tests/grammar/invalid_list/test.py
index 993ee81de..ceb27916f 100644
--- a/testsuite/tests/grammar/invalid_list/test.py
+++ b/testsuite/tests/grammar/invalid_list/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, Field, root_grammar_class
diff --git a/testsuite/tests/grammar/invalid_main_rule/test.out b/testsuite/tests/grammar/invalid_main_rule/test.out
index fa3ad35c5..88eab1b31 100644
--- a/testsuite/tests/grammar/invalid_main_rule/test.out
+++ b/testsuite/tests/grammar/invalid_main_rule/test.out
@@ -1,3 +1,3 @@
-File "test.py", line 21, In definition of grammar
+File "test.py", line 24, In definition of grammar
     Error: Invalid rule name specified for main rule: "main_rulezz". Did you mean "main_rule"?
 Done
diff --git a/testsuite/tests/grammar/invalid_main_rule/test.py b/testsuite/tests/grammar/invalid_main_rule/test.py
index a53beea6a..9b41781da 100644
--- a/testsuite/tests/grammar/invalid_main_rule/test.py
+++ b/testsuite/tests/grammar/invalid_main_rule/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import ASTNode, abstract, root_grammar_class
 from langkit.diagnostics import Diagnostics
 from langkit.parsers import Grammar, Row
@@ -27,4 +30,4 @@ def lang_def():
 
 
 emit_and_print_errors(lang_def)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/grammar/invalid_row/test.out b/testsuite/tests/grammar/invalid_row/test.out
index d11e06703..bf37aee0a 100644
--- a/testsuite/tests/grammar/invalid_row/test.out
+++ b/testsuite/tests/grammar/invalid_row/test.out
@@ -1,3 +1,3 @@
-File "test.py", line 30, In definition of grammar rule main_rule
+File "test.py", line 33, In definition of grammar rule main_rule
     Error: Grammar rules must yield an AST node
 Done
diff --git a/testsuite/tests/grammar/invalid_row/test.py b/testsuite/tests/grammar/invalid_row/test.py
index 9260ad496..74d951a13 100644
--- a/testsuite/tests/grammar/invalid_row/test.py
+++ b/testsuite/tests/grammar/invalid_row/test.py
@@ -2,6 +2,9 @@
 Test that top-level Row parsers are properly reported as errors.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, Field, root_grammar_class
diff --git a/testsuite/tests/grammar/invalid_rule_dup/test.out b/testsuite/tests/grammar/invalid_rule_dup/test.out
index c4466efc7..1875a821b 100644
--- a/testsuite/tests/grammar/invalid_rule_dup/test.out
+++ b/testsuite/tests/grammar/invalid_rule_dup/test.out
@@ -1,3 +1,3 @@
-File "test.py", line 28, In definition of rule 'sec_rule'
+File "test.py", line 31, In definition of rule 'sec_rule'
     Error: Rule 'sec_rule' is already present in the grammar
 Done
diff --git a/testsuite/tests/grammar/invalid_rule_dup/test.py b/testsuite/tests/grammar/invalid_rule_dup/test.py
index 56e63b6eb..6dfdd6043 100644
--- a/testsuite/tests/grammar/invalid_rule_dup/test.py
+++ b/testsuite/tests/grammar/invalid_rule_dup/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import ASTNode, abstract, root_grammar_class
 from langkit.diagnostics import Diagnostics
 from langkit.parsers import Grammar, Row
@@ -29,4 +32,4 @@ def lang_def():
     )
 
 emit_and_print_errors(lang_def)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/grammar/invalid_rule_usage/test.out b/testsuite/tests/grammar/invalid_rule_usage/test.out
index f7b74b00a..fe8b06db0 100644
--- a/testsuite/tests/grammar/invalid_rule_usage/test.out
+++ b/testsuite/tests/grammar/invalid_rule_usage/test.out
@@ -1,3 +1,3 @@
-File "test.py", line 24, In definition of grammar rule main_rule
+File "test.py", line 27, In definition of grammar rule main_rule
     Error: Wrong rule name: 'sec_rules'. Did you mean 'sec_rule'?
 Done
diff --git a/testsuite/tests/grammar/invalid_rule_usage/test.py b/testsuite/tests/grammar/invalid_rule_usage/test.py
index e6043b965..3930b6a33 100644
--- a/testsuite/tests/grammar/invalid_rule_usage/test.py
+++ b/testsuite/tests/grammar/invalid_rule_usage/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import ASTNode, abstract, root_grammar_class
 from langkit.diagnostics import Diagnostics
 from langkit.parsers import Grammar, Row
@@ -27,4 +30,4 @@ def lang_def():
 
 
 emit_and_print_errors(lang_def)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/grammar/newline/main.py b/testsuite/tests/grammar/newline/main.py
index 6719b6a2c..cdfac6552 100644
--- a/testsuite/tests/grammar/newline/main.py
+++ b/testsuite/tests/grammar/newline/main.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import libfoolang
 
 ctx = libfoolang.AnalysisContext()
@@ -6,9 +9,9 @@ ctx = libfoolang.AnalysisContext()
 def process(text):
     u = ctx.get_from_buffer('main.txt', text)
     if u.diagnostics:
-        print "Found errors:"
+        print("Found errors:")
         for d in u.diagnostics:
-            print "", d
+            print("", d)
     else:
         u.root.dump()
 
diff --git a/testsuite/tests/grammar/newline/test.py b/testsuite/tests/grammar/newline/test.py
index f64a0588a..ddbff08e6 100644
--- a/testsuite/tests/grammar/newline/test.py
+++ b/testsuite/tests/grammar/newline/test.py
@@ -2,6 +2,9 @@
 Test that Bind works when binding from env elements.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import (
@@ -94,4 +97,4 @@ foo_grammar.add_rules(
     main_rule=Or(A.comp, A.ind, A.nl)
 )
 build_and_run(foo_grammar, 'main.py', lexer=foo_lexer)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/grammar/recursive_list/test.py b/testsuite/tests/grammar/recursive_list/test.py
index a963ad56d..5ba500a1c 100644
--- a/testsuite/tests/grammar/recursive_list/test.py
+++ b/testsuite/tests/grammar/recursive_list/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, Field, root_grammar_class
 )
@@ -35,4 +38,4 @@ def lang_def():
 
 emit_and_print_errors(lang_def)
 
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/grammar/trailing_garbage/main.py b/testsuite/tests/grammar/trailing_garbage/main.py
index e26641860..7dd7ba705 100644
--- a/testsuite/tests/grammar/trailing_garbage/main.py
+++ b/testsuite/tests/grammar/trailing_garbage/main.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import libfoolang
 
 
diff --git a/testsuite/tests/grammar/trailing_garbage/test.py b/testsuite/tests/grammar/trailing_garbage/test.py
index c587edf25..9e05805b6 100644
--- a/testsuite/tests/grammar/trailing_garbage/test.py
+++ b/testsuite/tests/grammar/trailing_garbage/test.py
@@ -3,6 +3,9 @@ Test that garbage tokens left after the main parsing rule completes does not
 crash. It used to!
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, Field, root_grammar_class
@@ -30,4 +33,4 @@ foo_grammar.add_rules(
     main_rule=Row(Tok(Token.Number, keep=True)) ^ Literal,
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/grammar/unreferenced_node/test.out b/testsuite/tests/grammar/unreferenced_node/test.out
index fde907152..6168217f8 100644
--- a/testsuite/tests/grammar/unreferenced_node/test.out
+++ b/testsuite/tests/grammar/unreferenced_node/test.out
@@ -1,3 +1,3 @@
-File "test.py", line 21, in UnreferencedNode
+File "test.py", line 24, in UnreferencedNode
     Error: Unresolved ASTNode subclass. Use it in the grammar or provide a type annotation for all its fields
 Done
diff --git a/testsuite/tests/grammar/unreferenced_node/test.py b/testsuite/tests/grammar/unreferenced_node/test.py
index 1b622ba62..3e906a1b6 100644
--- a/testsuite/tests/grammar/unreferenced_node/test.py
+++ b/testsuite/tests/grammar/unreferenced_node/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import ASTNode, Field, abstract, root_grammar_class
 from langkit.diagnostics import Diagnostics
 from langkit.parsers import Grammar, Row
@@ -29,4 +32,4 @@ def lang_def():
 
 
 emit_and_print_errors(lang_def)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/lexical_envs/env_hook_unbound/test.out b/testsuite/tests/lexical_envs/env_hook_unbound/test.out
index 8278da220..7d805df6b 100644
--- a/testsuite/tests/lexical_envs/env_hook_unbound/test.out
+++ b/testsuite/tests/lexical_envs/env_hook_unbound/test.out
@@ -1,3 +1,3 @@
-File "test.py", line 20, in BarNode
+File "test.py", line 23, in BarNode
     Error: Cannot invoke the environment hook if CompileContext.bind_env_hook has not been called
 Done
diff --git a/testsuite/tests/lexical_envs/env_hook_unbound/test.py b/testsuite/tests/lexical_envs/env_hook_unbound/test.py
index ebafd7c33..841cafe1e 100644
--- a/testsuite/tests/lexical_envs/env_hook_unbound/test.py
+++ b/testsuite/tests/lexical_envs/env_hook_unbound/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, root_grammar_class
@@ -30,4 +33,4 @@ def lang_def():
 
 
 emit_and_print_errors(lang_def)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/lexical_envs/python_get/script.py b/testsuite/tests/lexical_envs/python_get/script.py
index f93001338..e6aa83d1c 100644
--- a/testsuite/tests/lexical_envs/python_get/script.py
+++ b/testsuite/tests/lexical_envs/python_get/script.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import sys
 
 import libfoolang
@@ -38,4 +41,4 @@ for node in nodes:
              '<none>')
         ))
 
-print 'Done.'
+print('Done.')
diff --git a/testsuite/tests/lexical_envs/python_get/test.py b/testsuite/tests/lexical_envs/python_get/test.py
index 0b8018116..bf5f8f19d 100644
--- a/testsuite/tests/lexical_envs/python_get/test.py
+++ b/testsuite/tests/lexical_envs/python_get/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, Field, Struct, abstract, env_metadata, root_grammar_class
 )
diff --git a/testsuite/tests/properties/analysis_unit/main.py b/testsuite/tests/properties/analysis_unit/main.py
index e6b0ccd4f..a120aabbc 100644
--- a/testsuite/tests/properties/analysis_unit/main.py
+++ b/testsuite/tests/properties/analysis_unit/main.py
@@ -1,4 +1,7 @@
-print 'main.py: Running...'
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
+print('main.py: Running...')
 
 
 import sys
@@ -8,7 +11,7 @@ import libfoolang
 
 ctx = libfoolang.AnalysisContext()
 for f in ('main.txt', ):
-    print '=== {} ==='.format(f)
+    print('=== {} ==='.format(f))
     u = ctx.get_from_file(f)
     if u.diagnostics:
         for d in u.diagnostics:
@@ -16,6 +19,6 @@ for f in ('main.txt', ):
         sys.exit(1)
 
     u.populate_lexical_env()
-    print 'result = {}'.format(u.root.p_result)
+    print('result = {}'.format(u.root.p_result))
 
-print 'main.py: Done.'
+print('main.py: Done.')
diff --git a/testsuite/tests/properties/analysis_unit/test.py b/testsuite/tests/properties/analysis_unit/test.py
index 56a30de55..67e80761e 100644
--- a/testsuite/tests/properties/analysis_unit/test.py
+++ b/testsuite/tests/properties/analysis_unit/test.py
@@ -2,6 +2,9 @@
 Test the handling of analysis units in the properties DSL.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import (
@@ -62,4 +65,4 @@ foo_grammar.add_rules(
     ),
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/analysis_unit_from_node/main.py b/testsuite/tests/properties/analysis_unit_from_node/main.py
index 64f9bdc8d..929c828da 100644
--- a/testsuite/tests/properties/analysis_unit_from_node/main.py
+++ b/testsuite/tests/properties/analysis_unit_from_node/main.py
@@ -1,4 +1,7 @@
-print 'main.py: Running...'
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
+print('main.py: Running...')
 
 
 import sys
@@ -15,6 +18,6 @@ if u.diagnostics:
 
 u.populate_lexical_env()
 for node in u.root.findall(lambda _: True):
-    print '{}.root = {}'.format(node, node.p_root_node)
+    print('{}.root = {}'.format(node, node.p_root_node))
 
-print 'main.py: Done.'
+print('main.py: Done.')
diff --git a/testsuite/tests/properties/analysis_unit_from_node/test.py b/testsuite/tests/properties/analysis_unit_from_node/test.py
index 8ac1e5550..f3af1b6f7 100644
--- a/testsuite/tests/properties/analysis_unit_from_node/test.py
+++ b/testsuite/tests/properties/analysis_unit_from_node/test.py
@@ -2,6 +2,9 @@
 Test getting the analysis unit of a node in the properties DSL.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import (
@@ -48,4 +51,4 @@ foo_grammar.add_rules(
     atom=Row(Tok(Token.Number, keep=True)) ^ Literal,
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/env_element_bind/main.py b/testsuite/tests/properties/env_element_bind/main.py
index e69de29bb..800d82e7e 100644
--- a/testsuite/tests/properties/env_element_bind/main.py
+++ b/testsuite/tests/properties/env_element_bind/main.py
@@ -0,0 +1,2 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
diff --git a/testsuite/tests/properties/env_element_bind/test.py b/testsuite/tests/properties/env_element_bind/test.py
index 2cdfdbc84..7b91fd929 100644
--- a/testsuite/tests/properties/env_element_bind/test.py
+++ b/testsuite/tests/properties/env_element_bind/test.py
@@ -2,6 +2,9 @@
 Test that Bind works when binding from env elements.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import (
@@ -43,4 +46,4 @@ foo_grammar.add_rules(
     main_rule=Row(Tok(Token.Number, keep=True)) ^ Literal,
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/env_element_cast/main.py b/testsuite/tests/properties/env_element_cast/main.py
index e69de29bb..800d82e7e 100644
--- a/testsuite/tests/properties/env_element_cast/main.py
+++ b/testsuite/tests/properties/env_element_cast/main.py
@@ -0,0 +1,2 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
diff --git a/testsuite/tests/properties/env_element_cast/test.py b/testsuite/tests/properties/env_element_cast/test.py
index d92dbe3f8..5cd4ed742 100644
--- a/testsuite/tests/properties/env_element_cast/test.py
+++ b/testsuite/tests/properties/env_element_cast/test.py
@@ -3,6 +3,9 @@ Test that garbage tokens left after the main parsing rule completes does not
 crash. It used to!
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, Field, root_grammar_class
@@ -45,4 +48,4 @@ foo_grammar.add_rules(
     main_rule=Row(Tok(Token.Number, keep=True)) ^ Literal,
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/env_element_field_access/main.py b/testsuite/tests/properties/env_element_field_access/main.py
index e69de29bb..800d82e7e 100644
--- a/testsuite/tests/properties/env_element_field_access/main.py
+++ b/testsuite/tests/properties/env_element_field_access/main.py
@@ -0,0 +1,2 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
diff --git a/testsuite/tests/properties/env_element_field_access/test.py b/testsuite/tests/properties/env_element_field_access/test.py
index 2cc960075..1bd4d94cc 100644
--- a/testsuite/tests/properties/env_element_field_access/test.py
+++ b/testsuite/tests/properties/env_element_field_access/test.py
@@ -2,6 +2,9 @@
 Tests that it is possible to call a property of type T on an EnvElement[T].
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, Field, root_grammar_class, LongType
@@ -44,4 +47,4 @@ foo_grammar.add_rules(
     main_rule=Row(Tok(Token.Number, keep=True)) ^ Literal,
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/env_element_match/main.py b/testsuite/tests/properties/env_element_match/main.py
index e69de29bb..800d82e7e 100644
--- a/testsuite/tests/properties/env_element_match/main.py
+++ b/testsuite/tests/properties/env_element_match/main.py
@@ -0,0 +1,2 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
diff --git a/testsuite/tests/properties/env_element_match/test.py b/testsuite/tests/properties/env_element_match/test.py
index 7751db4f3..157abc201 100644
--- a/testsuite/tests/properties/env_element_match/test.py
+++ b/testsuite/tests/properties/env_element_match/test.py
@@ -3,6 +3,9 @@ Test that garbage tokens left after the main parsing rule completes does not
 crash. It used to!
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, Field, root_grammar_class
@@ -47,4 +50,4 @@ foo_grammar.add_rules(
     main_rule=Row(Tok(Token.Number, keep=True)) ^ Literal,
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/external/main.py b/testsuite/tests/properties/external/main.py
index b15690232..2b9629122 100644
--- a/testsuite/tests/properties/external/main.py
+++ b/testsuite/tests/properties/external/main.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import sys
 
 import libfoolang
@@ -13,5 +16,5 @@ if u.diagnostics:
     sys.exit(1)
 
 u.populate_lexical_env()
-print 'Evaluating {}'.format(text)
-print 'result = {}'.format(u.root.p_result)
+print('Evaluating {}'.format(text))
+print('result = {}'.format(u.root.p_result))
diff --git a/testsuite/tests/properties/external/test.py b/testsuite/tests/properties/external/test.py
index c6f889be1..8fb2ffff5 100644
--- a/testsuite/tests/properties/external/test.py
+++ b/testsuite/tests/properties/external/test.py
@@ -2,6 +2,9 @@
 Test that external properties build and run properly.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import (
@@ -52,4 +55,4 @@ foo_grammar.add_rules(
     atom=Row(Tok(Token.Number, keep=True)) ^ Literal,
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/implicit_env/test.out b/testsuite/tests/properties/implicit_env/test.out
index 96d4fd185..98626cb4b 100644
--- a/testsuite/tests/properties/implicit_env/test.out
+++ b/testsuite/tests/properties/implicit_env/test.out
@@ -4,7 +4,7 @@ Code generation was successful
   ConcreteNode.p_prop: no implicit env
 
 == abstract: default, concrete: implicit env ==
-File "test.py", line 42, in ConcreteNode.prop
+File "test.py", line 45, in ConcreteNode.prop
     Error: AbstractNode.p_prop has no implicit environment parameter, so should have ConcreteNode.p_prop
 
 == abstract: default, concrete: no implicit env ==
@@ -23,7 +23,7 @@ Code generation was successful
   ConcreteNode.p_prop: implicit env
 
 == abstract: implicit env, concrete: no implicit env ==
-File "test.py", line 42, in ConcreteNode.prop
+File "test.py", line 45, in ConcreteNode.prop
     Error: AbstractNode.p_prop has an implicit environment parameter, so should have ConcreteNode.p_prop
 
 == abstract: no implicit env, concrete: default ==
@@ -32,7 +32,7 @@ Code generation was successful
   ConcreteNode.p_prop: no implicit env
 
 == abstract: no implicit env, concrete: implicit env ==
-File "test.py", line 42, in ConcreteNode.prop
+File "test.py", line 45, in ConcreteNode.prop
     Error: AbstractNode.p_prop has no implicit environment parameter, so should have ConcreteNode.p_prop
 
 == abstract: no implicit env, concrete: no implicit env ==
diff --git a/testsuite/tests/properties/implicit_env/test.py b/testsuite/tests/properties/implicit_env/test.py
index 67da01c49..2b49703e9 100644
--- a/testsuite/tests/properties/implicit_env/test.py
+++ b/testsuite/tests/properties/implicit_env/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import itertools
 import os.path
 
@@ -22,10 +25,10 @@ def run(abstract_has_implicit_env, concrete_has_implicit_env):
         True: 'implicit env',
         False: 'no implicit env',
     }
-    print '== abstract: {}, concrete: {} =='.format(
+    print('== abstract: {}, concrete: {} =='.format(
         fmt_value[abstract_has_implicit_env],
         fmt_value[concrete_has_implicit_env]
-    )
+    ))
     Diagnostics.set_lang_source_dir(os.path.abspath(__file__))
 
     @root_grammar_class()
@@ -51,8 +54,8 @@ def run(abstract_has_implicit_env, concrete_has_implicit_env):
     if emit_and_print_errors(lang_def):
         for fld in (AbstractNode._fields['prop'],
                     ConcreteNode._fields['prop']):
-            print '  {}: {}'.format(fld.qualname,
-                                    fmt_value[fld.has_implicit_env])
+            print('  {}: {}'.format(fld.qualname,
+                                    fmt_value[fld.has_implicit_env]))
     print('')
 
 
@@ -60,4 +63,4 @@ attribute_values = (None, True, False)
 for p1, p2 in itertools.product(attribute_values, attribute_values):
     run(p1, p2)
 
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/internal_decl/test.out b/testsuite/tests/properties/internal_decl/test.out
index a87b82b4e..20d62f022 100644
--- a/testsuite/tests/properties/internal_decl/test.out
+++ b/testsuite/tests/properties/internal_decl/test.out
@@ -1,3 +1,3 @@
-File "test.py", line 17, in BarNode._prop
+File "test.py", line 20, in BarNode._prop
     Error: Underscore-prefixed field names are not allowed
 Done
diff --git a/testsuite/tests/properties/internal_decl/test.py b/testsuite/tests/properties/internal_decl/test.py
index bd8377430..6f1305311 100644
--- a/testsuite/tests/properties/internal_decl/test.py
+++ b/testsuite/tests/properties/internal_decl/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from os import path
 
 from langkit.compiled_types import ASTNode, root_grammar_class
@@ -19,4 +22,4 @@ try:
 except DiagnosticError:
     pass
 
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/internal_use/test.out b/testsuite/tests/properties/internal_use/test.out
index fc8c48fcd..8d261e840 100644
--- a/testsuite/tests/properties/internal_use/test.out
+++ b/testsuite/tests/properties/internal_use/test.out
@@ -1,4 +1,4 @@
-File "test.py", line 43, in Def.faulty_prop
-  line 43, in FieldAccess expression
+File "test.py", line 46, in Def.faulty_prop
+  line 46, in FieldAccess expression
     Error: Def.internal_env_value_1 is for internal use only
 Done
diff --git a/testsuite/tests/properties/internal_use/test.py b/testsuite/tests/properties/internal_use/test.py
index 8fcbd283e..b3b8747d2 100644
--- a/testsuite/tests/properties/internal_use/test.py
+++ b/testsuite/tests/properties/internal_use/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from os import path
 
 from langkit.compiled_types import (
@@ -69,4 +72,4 @@ def lang_def():
     return foo_grammar
 
 emit_and_print_errors(lang_def)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_analysis_unit_expr/test.out b/testsuite/tests/properties/invalid_analysis_unit_expr/test.out
index a19d750d0..e2cb141b8 100644
--- a/testsuite/tests/properties/invalid_analysis_unit_expr/test.out
+++ b/testsuite/tests/properties/invalid_analysis_unit_expr/test.out
@@ -1,5 +1,5 @@
 == Invalid field ==
-File "test.py", line 25, in Example.result
+File "test.py", line 28, in Example.result
     Error: Invalid property for analysis unit: foobar
 
 Done
diff --git a/testsuite/tests/properties/invalid_analysis_unit_expr/test.py b/testsuite/tests/properties/invalid_analysis_unit_expr/test.py
index 069937ef4..e5ecd433d 100644
--- a/testsuite/tests/properties/invalid_analysis_unit_expr/test.py
+++ b/testsuite/tests/properties/invalid_analysis_unit_expr/test.py
@@ -3,6 +3,9 @@ Test that invalid uses of analysis unit in the properties DSL are properly
 detected and reported.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, root_grammar_class
@@ -33,4 +36,4 @@ def run(name, prop):
 
 
 run('Invalid field', Self.unit.foobar)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_bind/test.out b/testsuite/tests/properties/invalid_bind/test.out
index 087b954c2..d04e33019 100644
--- a/testsuite/tests/properties/invalid_bind/test.out
+++ b/testsuite/tests/properties/invalid_bind/test.out
@@ -1,16 +1,16 @@
 == Incorrect bind eq_prop 1 ==
-File "test.py", line 31, in BarNode.main_prop
-  line 33, in Bind expression
+File "test.py", line 34, in BarNode.main_prop
+  line 36, in Bind expression
     Error: Equality property must return boolean
 
 == Incorrect bind eq_prop 2 ==
-File "test.py", line 31, in BarNode.main_prop
-  line 33, in Bind expression
+File "test.py", line 34, in BarNode.main_prop
+  line 36, in Bind expression
     Error: Expected 1 argument for eq_prop, got 0
 
 == Incorrect bind eq_prop 3 ==
-File "test.py", line 31, in BarNode.main_prop
-  line 33, in Bind expression
+File "test.py", line 34, in BarNode.main_prop
+  line 36, in Bind expression
     Error: Self and first argument should be of the same type
 
 == Correct bind eq_prop ==
diff --git a/testsuite/tests/properties/invalid_bind/test.py b/testsuite/tests/properties/invalid_bind/test.py
index 6fe133b1b..a9c8f9bd0 100644
--- a/testsuite/tests/properties/invalid_bind/test.py
+++ b/testsuite/tests/properties/invalid_bind/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, root_grammar_class, LogicVarType, UserField, T
 )
@@ -59,4 +62,4 @@ run("Incorrect bind eq_prop 1", "BazNode.fields.prop")
 run("Incorrect bind eq_prop 2", "BazNode.fields.prop2")
 run("Incorrect bind eq_prop 3", "BazNode.fields.prop3")
 run("Correct bind eq_prop", "BazNode.fields.prop4")
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_call/test.out b/testsuite/tests/properties/invalid_call/test.out
index e94a7dc98..40359c877 100644
--- a/testsuite/tests/properties/invalid_call/test.out
+++ b/testsuite/tests/properties/invalid_call/test.out
@@ -2,18 +2,18 @@
 Code generation was successful
 
 == Incorrect call code 1 ==
-File "test.py", line 30, in BarNode.prop
-  line 44, in FieldAccess expression
+File "test.py", line 33, in BarNode.prop
+  line 47, in FieldAccess expression
     Error: Type BarNode has no 'non_exisisting_prop' field or property
 
 == Incorrect call code 2 ==
-File "test.py", line 30, in BarNode.prop
-  line 45, in FieldAccess expression
+File "test.py", line 33, in BarNode.prop
+  line 48, in FieldAccess expression
     Error: Invalid number of arguments in the call to BarNode.p_prop_2: 1 expected but got 2
 
 == Incorrect call code 3 ==
-File "test.py", line 30, in BarNode.prop
-  line 46, in No expression
+File "test.py", line 33, in BarNode.prop
+  line 49, in No expression
     Error: Invalid X actual (#1) for BarNode.p_prop_2: expected Integer but got FooNode
 
 Done
diff --git a/testsuite/tests/properties/invalid_call/test.py b/testsuite/tests/properties/invalid_call/test.py
index 6fc7a72e8..4e1e6c0b5 100644
--- a/testsuite/tests/properties/invalid_call/test.py
+++ b/testsuite/tests/properties/invalid_call/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, root_grammar_class, LongType
 )
@@ -44,4 +47,4 @@ run("Correct code", lambda: Self.prop_2(12))
 run("Incorrect call code 1", lambda: Self.non_exisisting_prop(12))
 run("Incorrect call code 2", lambda: Self.prop_2(12, 15))
 run("Incorrect call code 3", lambda: Self.prop_2(No(FooNode)))
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_cast/test.out b/testsuite/tests/properties/invalid_cast/test.out
index a423a30b1..9f099e6e7 100644
--- a/testsuite/tests/properties/invalid_cast/test.out
+++ b/testsuite/tests/properties/invalid_cast/test.out
@@ -2,12 +2,12 @@
 Code generation was successful
 
 == Invalid cast 1 ==
-File "test.py", line 35, in ListNode.prop
+File "test.py", line 38, in ListNode.prop
     Error: One can only cast to an ASTNode subtype or to an env_element
 
 == Invalid cast 2 ==
-File "test.py", line 35, in ListNode.prop
-  line 56, in FieldAccess expression
+File "test.py", line 38, in ListNode.prop
+  line 59, in FieldAccess expression
     Error: Cannot cast BarNode to ListNode: only (up/down)casting is allowed
 
 Done
diff --git a/testsuite/tests/properties/invalid_cast/test.py b/testsuite/tests/properties/invalid_cast/test.py
index 6bb98caec..2301696ba 100644
--- a/testsuite/tests/properties/invalid_cast/test.py
+++ b/testsuite/tests/properties/invalid_cast/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, root_grammar_class, LongType, Field
 )
@@ -54,4 +57,4 @@ def run(name, expr):
 run("Correct code", lambda: Self.parent.cast(BarNode))
 run("Invalid cast 1", lambda: Self.parent.cast(LongType))
 run("Invalid cast 2", lambda: Self.bar_node_parent.cast(ListNode))
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_env/test.out b/testsuite/tests/properties/invalid_env/test.out
index 3c42e91c2..517059069 100644
--- a/testsuite/tests/properties/invalid_env/test.out
+++ b/testsuite/tests/properties/invalid_env/test.out
@@ -1,10 +1,10 @@
 == <get(<Env>, <FieldAccess <AbstractVariable Self> tok>)> ==
-File "test.py", line 32, in ExampleNode.prop
+File "test.py", line 35, in ExampleNode.prop
     Error: This property has no implicit environment parameter: please use the eval_in_env construct to bind an environment first.
 
 == <FieldAccess <AbstractVariable Self> implicit_prop> ==
-File "test.py", line 32, in ExampleNode.prop
-  line 46, in FieldAccess expression
+File "test.py", line 35, in ExampleNode.prop
+  line 49, in FieldAccess expression
     Error: This property has no implicit environment parameter whereas ExampleNode.p_implicit_prop expects one: please use the eval_in_env construct to bind an environment first.
 
 == <eval_in_env(<FieldAccess <AbstractVariable Self> node_env>, <get(<Env>, <FieldAccess <AbstractVariable Self> tok>)>)> ==
diff --git a/testsuite/tests/properties/invalid_env/test.py b/testsuite/tests/properties/invalid_env/test.py
index 4d67def43..d371d76c9 100644
--- a/testsuite/tests/properties/invalid_env/test.py
+++ b/testsuite/tests/properties/invalid_env/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, root_grammar_class, Field
 )
@@ -17,7 +20,7 @@ def run(expr):
 
     Diagnostics.set_lang_source_dir(path.abspath(__file__))
 
-    print '== {} =='.format(expr)
+    print('== {} =='.format(expr))
 
     @root_grammar_class()
     class FooNode(ASTNode):
@@ -46,4 +49,4 @@ run(Env.get(Self.tok))
 run(Self.implicit_prop)
 run(Self.node_env.eval_in_env(Env.get(Self.tok)))
 run(Self.node_env.eval_in_env(Self.implicit_prop))
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_external/test.out b/testsuite/tests/properties/invalid_external/test.out
index 8f4aec1f3..5863018fd 100644
--- a/testsuite/tests/properties/invalid_external/test.out
+++ b/testsuite/tests/properties/invalid_external/test.out
@@ -1,13 +1,13 @@
 == Missing type ==
-File "test.py", line 42, in AbstractExample.p
+File "test.py", line 45, in AbstractExample.p
     Error: This property requires an explicit return type
 
 == Invalid abstract ==
-File "test.py", line 45, in AbstractExample.p
+File "test.py", line 48, in AbstractExample.p
     Error: An external property cannot be abstract
 
 == Invalid memoized ==
-File "test.py", line 49, in AbstractExample.p
+File "test.py", line 52, in AbstractExample.p
     Error: An external property cannot be memoized
 
 Done
diff --git a/testsuite/tests/properties/invalid_external/test.py b/testsuite/tests/properties/invalid_external/test.py
index e8d32dfd8..956041993 100644
--- a/testsuite/tests/properties/invalid_external/test.py
+++ b/testsuite/tests/properties/invalid_external/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import ASTNode, T, abstract, root_grammar_class
 from langkit.diagnostics import Diagnostics
 from langkit.expressions import ExternalProperty, Property, Self
@@ -47,4 +50,4 @@ run("Invalid abstract",
 
 run("Invalid memoized",
     lambda: ExternalProperty(memoized=True))
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_let/test.out b/testsuite/tests/properties/invalid_let/test.out
index b565aa3e7..88b11afaf 100644
--- a/testsuite/tests/properties/invalid_let/test.out
+++ b/testsuite/tests/properties/invalid_let/test.out
@@ -2,11 +2,11 @@
 Code generation was successful
 
 == Missing var value ==
-File "test.py", line 29, in BarNode.prop
+File "test.py", line 32, in BarNode.prop
     Error: All Let expression function arguments must have default values
 
 == Invalid args ==
-File "test.py", line 29, in BarNode.prop
+File "test.py", line 32, in BarNode.prop
     Error: Invalid function for Let expression (*args and **kwargs not accepted)
 
 Done
diff --git a/testsuite/tests/properties/invalid_let/test.py b/testsuite/tests/properties/invalid_let/test.py
index 88823640d..d0399537b 100644
--- a/testsuite/tests/properties/invalid_let/test.py
+++ b/testsuite/tests/properties/invalid_let/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, root_grammar_class
 )
@@ -43,4 +46,4 @@ run("Correct code", lambda: Let(lambda a=Literal(1): a))
 run("Missing var value", lambda: Let(lambda a: a))
 run("Invalid args", lambda: Let(lambda a=Literal(1), *b, **c: a))
 
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_map/test.out b/testsuite/tests/properties/invalid_map/test.out
index cc07bf314..3a46c7496 100644
--- a/testsuite/tests/properties/invalid_map/test.out
+++ b/testsuite/tests/properties/invalid_map/test.out
@@ -2,15 +2,15 @@
 Code generation was successful
 
 == Incorrect map code 1 ==
-File "test.py", line 34, in ListNode.prop
+File "test.py", line 37, in ListNode.prop
     Error: Invalid collection iteration lambda: only one or two parameters expected
 
 == Incorrect map code 2 ==
-File "test.py", line 34, in ListNode.prop
+File "test.py", line 37, in ListNode.prop
     Error: Invalid collection iteration lambda: No default values allowed for arguments
 
 == Incorrect map code 3 ==
-File "test.py", line 34, in ListNode.prop
+File "test.py", line 37, in ListNode.prop
     Error: Invalid collection iteration lambda: no *args or **kwargs
 
 Done
diff --git a/testsuite/tests/properties/invalid_map/test.py b/testsuite/tests/properties/invalid_map/test.py
index d9c19263c..4c7006fc6 100644
--- a/testsuite/tests/properties/invalid_map/test.py
+++ b/testsuite/tests/properties/invalid_map/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, root_grammar_class, Field
 )
@@ -53,4 +56,4 @@ run("Correct code", lambda: Self.nb_list.map(lambda x: x))
 run("Incorrect map code 1", lambda: Self.nb_list.map(lambda x, y, z: x))
 run("Incorrect map code 2", lambda: Self.nb_list.map(lambda x=12: x))
 run("Incorrect map code 3", lambda: Self.nb_list.map(lambda x, *y: x))
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_matchers/test.out b/testsuite/tests/properties/invalid_matchers/test.out
index 663db5a91..690192d3a 100644
--- a/testsuite/tests/properties/invalid_matchers/test.out
+++ b/testsuite/tests/properties/invalid_matchers/test.out
@@ -1,54 +1,54 @@
 == Missing NullNode ==
-File "test.py", line 51, in ExampleNode.prop
-  line 79, in Match expression
+File "test.py", line 54, in ExampleNode.prop
+  line 82, in Match expression
     Error: The following AST nodes have no handler: NullNode (all BodyNode subclasses require one)
 
 == Missing Expression ==
-File "test.py", line 51, in ExampleNode.prop
-  line 82, in Match expression
+File "test.py", line 54, in ExampleNode.prop
+  line 85, in Match expression
     Error: The following AST nodes have no handler: Expression (all BodyNode subclasses require one)
 
 == Missing Compound ==
-File "test.py", line 51, in ExampleNode.prop
-  line 86, in Match expression
+File "test.py", line 54, in ExampleNode.prop
+  line 89, in Match expression
     Error: The following AST nodes have no handler: Compound (all BodyNode subclasses require one)
 
 == Invalid type ==
-File "test.py", line 51, in ExampleNode.prop
+File "test.py", line 54, in ExampleNode.prop
     Error: Invalid matching type: Boolean
 
 == Irrelevant AST node ==
-File "test.py", line 51, in ExampleNode.prop
-  line 98, in Match expression
+File "test.py", line 54, in ExampleNode.prop
+  line 101, in Match expression
     Error: Cannot match FooNode (input type is BodyNode)
 
 == Default case after full coverage ==
-File "test.py", line 51, in ExampleNode.prop
-  line 104, in Match expression
+File "test.py", line 54, in ExampleNode.prop
+  line 107, in Match expression
     Warning: The #2 matcher (default one) is unreachable as all previous matchers cover all the nodes it can match
 Code generation was successful
 
 == Node after default case (1) ==
-File "test.py", line 51, in ExampleNode.prop
-  line 109, in Match expression
+File "test.py", line 54, in ExampleNode.prop
+  line 112, in Match expression
     Warning: The #2 matcher (BodyNode) is unreachable as all previous matchers cover all the nodes it can match
 Code generation was successful
 
 == Node after default case (2) ==
-File "test.py", line 51, in ExampleNode.prop
-  line 113, in Match expression
+File "test.py", line 54, in ExampleNode.prop
+  line 116, in Match expression
     Warning: The #2 matcher (Number) is unreachable as all previous matchers cover all the nodes it can match
 Code generation was successful
 
 == Node after full coverage (1) ==
-File "test.py", line 51, in ExampleNode.prop
-  line 118, in Match expression
+File "test.py", line 54, in ExampleNode.prop
+  line 121, in Match expression
     Warning: The #2 matcher (Number) is unreachable as all previous matchers cover all the nodes it can match
 Code generation was successful
 
 == Node after full coverage (2) ==
-File "test.py", line 51, in ExampleNode.prop
-  line 124, in Match expression
+File "test.py", line 54, in ExampleNode.prop
+  line 127, in Match expression
     Warning: The #4 matcher (BodyNode) is unreachable as all previous matchers cover all the nodes it can match
 Code generation was successful
 
diff --git a/testsuite/tests/properties/invalid_matchers/test.py b/testsuite/tests/properties/invalid_matchers/test.py
index d39941292..ce9eebb99 100644
--- a/testsuite/tests/properties/invalid_matchers/test.py
+++ b/testsuite/tests/properties/invalid_matchers/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, BoolType, Field, abstract, root_grammar_class
 )
@@ -124,4 +127,4 @@ run('Node after full coverage (2)', lambda: Self.body.match(
     lambda e=BodyNode: e.prop,
 ))
 
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_new/test.out b/testsuite/tests/properties/invalid_new/test.out
index 2564c65f1..6b1cfb8d7 100644
--- a/testsuite/tests/properties/invalid_new/test.out
+++ b/testsuite/tests/properties/invalid_new/test.out
@@ -2,18 +2,18 @@
 Code generation was successful
 
 == Incorrect new 1 ==
-File "test.py", line 33, in BarNode.prop
-  line 46, in New expression
+File "test.py", line 36, in BarNode.prop
+  line 49, in New expression
     Error: Values are missing for MyStruct fields: b
 
 == Incorrect new 2 ==
-File "test.py", line 33, in BarNode.prop
-  line 47, in No expression
+File "test.py", line 36, in BarNode.prop
+  line 50, in No expression
     Error: Wrong type for field b: expected Integer, got FooNode
 
 == Incorrect new 1 ==
-File "test.py", line 33, in BarNode.prop
-  line 49, in New expression
+File "test.py", line 36, in BarNode.prop
+  line 52, in New expression
     Error: Extraneous fields for MyStruct: c
 
 Done
diff --git a/testsuite/tests/properties/invalid_new/test.py b/testsuite/tests/properties/invalid_new/test.py
index dbb377bc5..384820cf4 100644
--- a/testsuite/tests/properties/invalid_new/test.py
+++ b/testsuite/tests/properties/invalid_new/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, root_grammar_class, LongType, Field, Struct
 )
@@ -47,4 +50,4 @@ run("Incorrect new 1", lambda: New(MyStruct, a=Literal(12)))
 run("Incorrect new 2", lambda: New(MyStruct, a=Literal(12), b=No(FooNode)))
 run("Incorrect new 1", lambda: New(MyStruct, a=Literal(12), b=Literal(15),
                                    c=Literal(19)))
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_new_node/test.out b/testsuite/tests/properties/invalid_new_node/test.out
index 2a787b520..8544d38f8 100644
--- a/testsuite/tests/properties/invalid_new_node/test.out
+++ b/testsuite/tests/properties/invalid_new_node/test.out
@@ -1,11 +1,11 @@
 == Not memoized ==
-File "test.py", line 33, in LiteralList.prop
-  line 50, in New expression
+File "test.py", line 36, in LiteralList.prop
+  line 53, in New expression
     Error: Node synthetization can only happen inside a memoized property
 
 == List synthetization ==
-File "test.py", line 33, in LiteralList.prop
-  line 51, in New expression
+File "test.py", line 36, in LiteralList.prop
+  line 54, in New expression
     Error: List node synthetization is not supported for now
 
 Done
diff --git a/testsuite/tests/properties/invalid_new_node/test.py b/testsuite/tests/properties/invalid_new_node/test.py
index b18ea669b..751377f2a 100644
--- a/testsuite/tests/properties/invalid_new_node/test.py
+++ b/testsuite/tests/properties/invalid_new_node/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, Field, T, root_grammar_class
@@ -49,4 +52,4 @@ def run(name, prop_fn, prop_memoized):
 
 run("Not memoized", lambda: New(T.EmptyNode), False)
 run("List synthetization", lambda: New(T.LiteralList), True)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_no/test.out b/testsuite/tests/properties/invalid_no/test.out
index 342df0c55..b8942f91f 100644
--- a/testsuite/tests/properties/invalid_no/test.out
+++ b/testsuite/tests/properties/invalid_no/test.out
@@ -2,7 +2,7 @@
 Code generation was successful
 
 == Incorrect No usage ==
-File "test.py", line 29, in BarNode.prop
+File "test.py", line 32, in BarNode.prop
     Error: Invalid type for Null expression: Integer
 
 Done
diff --git a/testsuite/tests/properties/invalid_no/test.py b/testsuite/tests/properties/invalid_no/test.py
index 76a9eeed9..86f5fe0fa 100644
--- a/testsuite/tests/properties/invalid_no/test.py
+++ b/testsuite/tests/properties/invalid_no/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, root_grammar_class, LongType
 )
@@ -41,4 +44,4 @@ def run(name, expr):
 
 run("Correct code", lambda: No(FooNode))
 run("Incorrect No usage", lambda: No(LongType))
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_prop_def/test.out b/testsuite/tests/properties/invalid_prop_def/test.out
index 5c7e717b1..2f9fc1ca0 100644
--- a/testsuite/tests/properties/invalid_prop_def/test.out
+++ b/testsuite/tests/properties/invalid_prop_def/test.out
@@ -2,27 +2,27 @@
 Code generation was successful
 
 == Incorrect property definition 1 ==
-File "test.py", line 48, in BarNode.propyprop
-    Error: Invalid abstract expression: ['Lol this is obviously wrong']
+File "test.py", line 51, in BarNode.propyprop
+    Error: Invalid abstract expression: [u'Lol this is obviously wrong']
 
 == Incorrect property definition 2 ==
-File "test.py", line 53, in BarNode.propyprop
+File "test.py", line 56, in BarNode.propyprop
     Error: Invalid function signature: no *args nor **kwargs allowed
 
 == Incorrect property definition 3 ==
-File "test.py", line 58, in BarNode.propyprop
+File "test.py", line 61, in BarNode.propyprop
     Error: All parameters must have an associated type as a default value
 
 == Incorrect property definition 4 ==
-File "test.py", line 63, in BarNode.propyprop
+File "test.py", line 66, in BarNode.propyprop
     Error: Cannot define reserved arguments (node, lex_env)
 
 == Incorrect property definition 5 ==
-File "test.py", line 68, in BarNode.propyprop
-    Error: Type provided is neither a CompiledType, neither a defered type reference: ['Obviously wrong']
+File "test.py", line 71, in BarNode.propyprop
+    Error: Type provided is neither a CompiledType, neither a defered type reference: [u'Obviously wrong']
 
 == Incorrect property definition 6 ==
-File "test.py", line 73, in BarNode.propyprop
+File "test.py", line 76, in BarNode.propyprop
     Error: Type provided is neither a CompiledType, neither a defered type reference: <class 'langkit.compiled_types.NodeMacro'>
 
 Done
diff --git a/testsuite/tests/properties/invalid_prop_def/test.py b/testsuite/tests/properties/invalid_prop_def/test.py
index 04f469073..db3fb0572 100644
--- a/testsuite/tests/properties/invalid_prop_def/test.py
+++ b/testsuite/tests/properties/invalid_prop_def/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, root_grammar_class, NodeMacro, LongType
 )
@@ -73,4 +76,4 @@ class Macro6(NodeMacro):
     propyprop = Property(lambda a=NodeMacro: a)
 run("Incorrect property definition 6", Macro6)
 
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_prop_literal/test.out b/testsuite/tests/properties/invalid_prop_literal/test.out
index 23bdb9fdc..3613bc400 100644
--- a/testsuite/tests/properties/invalid_prop_literal/test.out
+++ b/testsuite/tests/properties/invalid_prop_literal/test.out
@@ -3,7 +3,7 @@ Code generation was successful
 Valid case
 Code generation was successful
 Invalid case
-File "test.py", line 17, in FooNode.b
+File "test.py", line 20, in FooNode.b
     Error: Invalid abstract expression: 12.9
 
 Done
diff --git a/testsuite/tests/properties/invalid_prop_literal/test.py b/testsuite/tests/properties/invalid_prop_literal/test.py
index 20d1ab568..53c35b712 100644
--- a/testsuite/tests/properties/invalid_prop_literal/test.py
+++ b/testsuite/tests/properties/invalid_prop_literal/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import ASTNode, root_grammar_class
 from langkit.diagnostics import Diagnostics
 from langkit.expressions import Property
@@ -21,11 +24,11 @@ def make_lang_def(lit):
         return foo_grammar
     return lang_def
 
-print 'Valid case'
+print('Valid case')
 emit_and_print_errors(make_lang_def(12))
-print 'Valid case'
-emit_and_print_errors(make_lang_def("lol"))
-print 'Invalid case'
+print('Valid case')
+emit_and_print_errors(make_lang_def('lol'))
+print('Invalid case')
 emit_and_print_errors(make_lang_def(12.90))
 print('')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_prop_type/test.out b/testsuite/tests/properties/invalid_prop_type/test.out
index 8f4eed559..827b528da 100644
--- a/testsuite/tests/properties/invalid_prop_type/test.out
+++ b/testsuite/tests/properties/invalid_prop_type/test.out
@@ -1,6 +1,6 @@
-File "test.py", line 26, in BarNode.prop_2
-  line 26, in FieldAccess expression
-  line 22, in BarCode.prop_1
+File "test.py", line 29, in BarNode.prop_2
+  line 29, in FieldAccess expression
+  line 25, in BarCode.prop_1
     Error: Recursion loop in type inference for property BarCode.p_prop_1. Try to specify its return type explicitly.
 
 Done
diff --git a/testsuite/tests/properties/invalid_prop_type/test.py b/testsuite/tests/properties/invalid_prop_type/test.py
index 14d932909..4f4310a23 100644
--- a/testsuite/tests/properties/invalid_prop_type/test.py
+++ b/testsuite/tests/properties/invalid_prop_type/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, root_grammar_class, Field
 )
@@ -36,4 +39,4 @@ def lang_def():
 
 emit_and_print_errors(lang_def)
 print('')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/invalid_then/test.out b/testsuite/tests/properties/invalid_then/test.out
index 64958909b..ab3c3cdd8 100644
--- a/testsuite/tests/properties/invalid_then/test.out
+++ b/testsuite/tests/properties/invalid_then/test.out
@@ -1,13 +1,13 @@
 == No argument ==
-File "test.py", line 30, in Example.prop
+File "test.py", line 33, in Example.prop
     Error: Invalid lambda for Then expression: exactly one parameter is required, without a default value
 
 == Two arguments ==
-File "test.py", line 30, in Example.prop
+File "test.py", line 33, in Example.prop
     Error: Invalid lambda for Then expression: exactly one parameter is required, without a default value
 
 == Default value ==
-File "test.py", line 30, in Example.prop
+File "test.py", line 33, in Example.prop
     Error: Invalid lambda for Then expression: exactly one parameter is required, without a default value
 
 Done
diff --git a/testsuite/tests/properties/invalid_then/test.py b/testsuite/tests/properties/invalid_then/test.py
index aadf906f8..4b1d24f98 100644
--- a/testsuite/tests/properties/invalid_then/test.py
+++ b/testsuite/tests/properties/invalid_then/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, Field, abstract, root_grammar_class
 )
@@ -48,4 +51,4 @@ run('No argument', Self.name.then(lambda: Self))
 run('Two arguments', Self.name.then(lambda x, y: x.foo(y)))
 run('Default value', Self.name.then(lambda name=None: name))
 
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/let_underscore/main.py b/testsuite/tests/properties/let_underscore/main.py
index e69de29bb..800d82e7e 100644
--- a/testsuite/tests/properties/let_underscore/main.py
+++ b/testsuite/tests/properties/let_underscore/main.py
@@ -0,0 +1,2 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
diff --git a/testsuite/tests/properties/let_underscore/test.py b/testsuite/tests/properties/let_underscore/test.py
index 9f491f5b3..a0e365ec5 100644
--- a/testsuite/tests/properties/let_underscore/test.py
+++ b/testsuite/tests/properties/let_underscore/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, root_grammar_class
 )
@@ -24,4 +27,4 @@ class BarNode(FooNode):
 foo_grammar = Grammar('main_rule')
 foo_grammar.add_rules(main_rule=BarNode('example'))
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/new_node/main.py b/testsuite/tests/properties/new_node/main.py
index ef3a2f097..465eb8f18 100644
--- a/testsuite/tests/properties/new_node/main.py
+++ b/testsuite/tests/properties/new_node/main.py
@@ -1,4 +1,7 @@
-print 'main.py: Running...'
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
+print('main.py: Running...')
 
 
 import sys
@@ -15,4 +18,4 @@ if u.diagnostics:
 
 u.populate_lexical_env()
 u.root.p_prop.dump()
-print 'main.py: Done.'
+print('main.py: Done.')
diff --git a/testsuite/tests/properties/new_node/test.py b/testsuite/tests/properties/new_node/test.py
index 06a3fd928..b3ce5247e 100644
--- a/testsuite/tests/properties/new_node/test.py
+++ b/testsuite/tests/properties/new_node/test.py
@@ -2,6 +2,9 @@
 Test AST node synthetization and a basic use of it in the Python API.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, Field, Token, root_grammar_class
@@ -51,4 +54,4 @@ foo_grammar.add_rules(
     list_item=Row(Tok(LexToken.Number, keep=True)) ^ Literal,
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/nop_cast/test.out b/testsuite/tests/properties/nop_cast/test.out
index 949f5d4ae..c0f1a98dd 100644
--- a/testsuite/tests/properties/nop_cast/test.out
+++ b/testsuite/tests/properties/nop_cast/test.out
@@ -1,5 +1,5 @@
-File "test.py", line 19, in ExampleNode.prop
-  line 19, in Cast expression
+File "test.py", line 22, in ExampleNode.prop
+  line 22, in Cast expression
     Warning: Casting to the same type
 Code generation was successful
 Done
diff --git a/testsuite/tests/properties/nop_cast/test.py b/testsuite/tests/properties/nop_cast/test.py
index 86e55fde2..bf19c098d 100644
--- a/testsuite/tests/properties/nop_cast/test.py
+++ b/testsuite/tests/properties/nop_cast/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import ASTNode, T, root_grammar_class
 from langkit.diagnostics import Diagnostics
 from langkit.expressions import Property, Self
@@ -27,4 +30,4 @@ def lang_def():
     return foo_grammar
 
 emit_and_print_errors(lang_def)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/null_checks/main.py b/testsuite/tests/properties/null_checks/main.py
index d25886569..055b02c29 100644
--- a/testsuite/tests/properties/null_checks/main.py
+++ b/testsuite/tests/properties/null_checks/main.py
@@ -1,4 +1,7 @@
-print 'main.py: Running...'
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
+print('main.py: Running...')
 
 
 import sys
@@ -37,4 +40,4 @@ for node, prop in [
         result = 'PropertyError'
     print('{}.{}: {}'.format(node, prop, result))
 
-print 'main.py: Done.'
+print('main.py: Done.')
diff --git a/testsuite/tests/properties/null_checks/test.py b/testsuite/tests/properties/null_checks/test.py
index 719d3a388..91075bbd8 100644
--- a/testsuite/tests/properties/null_checks/test.py
+++ b/testsuite/tests/properties/null_checks/test.py
@@ -3,6 +3,9 @@ Test that property checks are properly emitted when null checks should trigger
 them.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import (
@@ -84,4 +87,4 @@ foo_grammar.add_rules(
     ),
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/override/test.out b/testsuite/tests/properties/override/test.out
index 549c34762..27791f627 100644
--- a/testsuite/tests/properties/override/test.out
+++ b/testsuite/tests/properties/override/test.out
@@ -1,14 +1,14 @@
 == FooNode ==
-File "test.py", line 38, in ExampleNode.get_random_node
-  line 38, in No expression
+File "test.py", line 41, in ExampleNode.get_random_node
+  line 41, in No expression
     Error: expected type MiddleNode, got FooNode instead (expected type comes from overridden base property in MiddleNode)
 
 == MiddleNode ==
 Code generation was successful
 
 == NullNode ==
-File "test.py", line 38, in ExampleNode.get_random_node
-  line 38, in No expression
+File "test.py", line 41, in ExampleNode.get_random_node
+  line 41, in No expression
     Error: expected type MiddleNode, got NullNode instead (expected type comes from overridden base property in MiddleNode)
 
 Done
diff --git a/testsuite/tests/properties/override/test.py b/testsuite/tests/properties/override/test.py
index 7ad59a4e0..706d36f16 100644
--- a/testsuite/tests/properties/override/test.py
+++ b/testsuite/tests/properties/override/test.py
@@ -3,6 +3,9 @@ Test that when a property B overrides a property A, B's return type must be a
 subtype of A's.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, T, abstract, root_grammar_class
@@ -58,4 +61,4 @@ run('FooNode', lambda T: T.FooNode)
 run('MiddleNode', lambda T: T.MiddleNode)
 run('NullNode', lambda T: T.NullNode)
 
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/populate_error/script.py b/testsuite/tests/properties/populate_error/script.py
index 7675a91f5..d44fabdc8 100644
--- a/testsuite/tests/properties/populate_error/script.py
+++ b/testsuite/tests/properties/populate_error/script.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import sys
 
 import libfoolang
@@ -10,11 +13,11 @@ if u.diagnostics:
         print(d)
     sys.exit(1)
 
-print 'Calling AnalysisUnit.populate_lexical_env()...'
+print('Calling AnalysisUnit.populate_lexical_env()...')
 try:
     u.populate_lexical_env()
 except libfoolang.PropertyError:
-    print 'Got a PropertyError as expected!'
+    print('Got a PropertyError as expected!')
 else:
-    print 'Got no PropertyError, which is unexpected!'
-print 'Done.'
+    print('Got no PropertyError, which is unexpected!')
+print('Done.')
diff --git a/testsuite/tests/properties/populate_error/test.py b/testsuite/tests/properties/populate_error/test.py
index 9d7e2185f..e6f9bca74 100644
--- a/testsuite/tests/properties/populate_error/test.py
+++ b/testsuite/tests/properties/populate_error/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, root_grammar_class
diff --git a/testsuite/tests/properties/privacy/test.out b/testsuite/tests/properties/privacy/test.out
index 16d8b8136..dc4dc99c9 100644
--- a/testsuite/tests/properties/privacy/test.out
+++ b/testsuite/tests/properties/privacy/test.out
@@ -4,7 +4,7 @@ Code generation was successful
   ConcreteNode.p_prop: private
 
 == abstract: default, concrete: public ==
-File "test.py", line 41, in ConcreteNode.prop
+File "test.py", line 44, in ConcreteNode.prop
     Error: AbstractNode.p_prop is private, so should be ConcreteNode.p_prop
 
 == abstract: default, concrete: private ==
@@ -23,7 +23,7 @@ Code generation was successful
   ConcreteNode.p_prop: public
 
 == abstract: public, concrete: private ==
-File "test.py", line 41, in ConcreteNode.prop
+File "test.py", line 44, in ConcreteNode.prop
     Error: AbstractNode.p_prop is public, so should be ConcreteNode.p_prop
 
 == abstract: private, concrete: default ==
@@ -32,7 +32,7 @@ Code generation was successful
   ConcreteNode.p_prop: private
 
 == abstract: private, concrete: public ==
-File "test.py", line 41, in ConcreteNode.prop
+File "test.py", line 44, in ConcreteNode.prop
     Error: AbstractNode.p_prop is private, so should be ConcreteNode.p_prop
 
 == abstract: private, concrete: private ==
diff --git a/testsuite/tests/properties/privacy/test.py b/testsuite/tests/properties/privacy/test.py
index 3c56a789d..88b9e55e6 100644
--- a/testsuite/tests/properties/privacy/test.py
+++ b/testsuite/tests/properties/privacy/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import itertools
 import os.path
 
@@ -22,10 +25,10 @@ def run(abstract_public, concrete_public):
         True: 'public',
         False: 'private',
     }
-    print '== abstract: {}, concrete: {} =='.format(
+    print('== abstract: {}, concrete: {} =='.format(
         fmt_privacy[abstract_public],
         fmt_privacy[concrete_public]
-    )
+    ))
     Diagnostics.set_lang_source_dir(os.path.abspath(__file__))
 
     @root_grammar_class()
@@ -52,7 +55,7 @@ def run(abstract_public, concrete_public):
     if emit_and_print_errors(lang_def):
         for fld in (AbstractNode._fields['prop'],
                     ConcreteNode._fields['prop']):
-            print '  {}: {}'.format(fld.qualname, fmt_privacy[fld.is_public])
+            print('  {}: {}'.format(fld.qualname, fmt_privacy[fld.is_public]))
     print('')
 
 
@@ -60,4 +63,4 @@ privacy_levels = (None, True, False)
 for p1, p2 in itertools.product(privacy_levels, privacy_levels):
     run(p1, p2)
 
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/unused_private_props/test.out b/testsuite/tests/properties/unused_private_props/test.out
index 6b9ba52eb..73efe3174 100644
--- a/testsuite/tests/properties/unused_private_props/test.out
+++ b/testsuite/tests/properties/unused_private_props/test.out
@@ -1,6 +1,6 @@
-File "test.py", line 27, in FooNode.as_expr
+File "test.py", line 30, in FooNode.as_expr
     Warning: This private property is unused
-File "test.py", line 34, in Expression.result
+File "test.py", line 37, in Expression.result
     Warning: This private abstraction is unused
 Code generation was successful
 Done
diff --git a/testsuite/tests/properties/unused_private_props/test.py b/testsuite/tests/properties/unused_private_props/test.py
index 02b52d136..01d2115d7 100644
--- a/testsuite/tests/properties/unused_private_props/test.py
+++ b/testsuite/tests/properties/unused_private_props/test.py
@@ -2,6 +2,9 @@
 Test the handling of analysis units in the properties DSL.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import (
@@ -87,4 +90,4 @@ foo_grammar.add_rules(
     ),
 )
 emit_and_print_errors(lambda: foo_grammar)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/properties/warn_unused/test.out b/testsuite/tests/properties/warn_unused/test.out
index a58bf263a..fa7184390 100644
--- a/testsuite/tests/properties/warn_unused/test.out
+++ b/testsuite/tests/properties/warn_unused/test.out
@@ -1,16 +1,16 @@
-File "test.py", line 32, in ExampleList.unused_param
+File "test.py", line 35, in ExampleList.unused_param
     Warning: The following bindings are not used: ex_param
-File "test.py", line 32, in ExampleList.unused_param
+File "test.py", line 35, in ExampleList.unused_param
     Warning: The following bindings are used even though they are supposed to be ignored: ex_wrongly_used_param
-File "test.py", line 36, in ExampleList.unused_block_var
+File "test.py", line 39, in ExampleList.unused_block_var
     Warning: The following bindings are not used: block_var
-File "test.py", line 44, in ExampleList.unused_let_var
+File "test.py", line 47, in ExampleList.unused_let_var
     Warning: The following bindings are not used: ex_list
-File "test.py", line 50, in ExampleList.unused_loop_var
+File "test.py", line 53, in ExampleList.unused_loop_var
     Warning: The following bindings are not used: ex_item
-File "test.py", line 55, in ExampleList.unused_then_var
+File "test.py", line 58, in ExampleList.unused_then_var
     Warning: The following bindings are not used: ex_items
-File "test.py", line 68, in ExampleList.unused_match_var
+File "test.py", line 71, in ExampleList.unused_match_var
     Warning: The following bindings are not used: ex
 Code generation was successful
 Done
diff --git a/testsuite/tests/properties/warn_unused/test.py b/testsuite/tests/properties/warn_unused/test.py
index 639e7749a..e8f77d82c 100644
--- a/testsuite/tests/properties/warn_unused/test.py
+++ b/testsuite/tests/properties/warn_unused/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, BoolType, Field, T, root_grammar_class
 )
@@ -82,4 +85,4 @@ def lang_def():
 
 
 emit_and_print_errors(lang_def)
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/python-api/ghost_nodes/main.py b/testsuite/tests/python-api/ghost_nodes/main.py
index 1a47bf2cf..9f8d18bba 100644
--- a/testsuite/tests/python-api/ghost_nodes/main.py
+++ b/testsuite/tests/python-api/ghost_nodes/main.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import libfoolang
 
 
@@ -10,4 +13,4 @@ for node in unit.root.findall(lambda _: True):
     ))
     assert not node.text or not node.is_ghost
 
-print 'Done.'
+print('Done.')
diff --git a/testsuite/tests/python-api/ghost_nodes/test.py b/testsuite/tests/python-api/ghost_nodes/test.py
index 6c1d82c31..c249bc559 100644
--- a/testsuite/tests/python-api/ghost_nodes/test.py
+++ b/testsuite/tests/python-api/ghost_nodes/test.py
@@ -2,6 +2,9 @@
 Test the handling of analysis units in the properties DSL.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, Field, T, root_grammar_class
@@ -44,4 +47,4 @@ foo_grammar.add_rules(
     ),
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/python-api/node_negative_index/main.py b/testsuite/tests/python-api/node_negative_index/main.py
index 514950d58..52f88559d 100644
--- a/testsuite/tests/python-api/node_negative_index/main.py
+++ b/testsuite/tests/python-api/node_negative_index/main.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import libfoolang
 
 
diff --git a/testsuite/tests/python-api/node_negative_index/test.py b/testsuite/tests/python-api/node_negative_index/test.py
index 3bf096181..869cc1f81 100644
--- a/testsuite/tests/python-api/node_negative_index/test.py
+++ b/testsuite/tests/python-api/node_negative_index/test.py
@@ -3,6 +3,9 @@ Test the handling of negative indexes in the Python binding of AST nodes child
 getters.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import ASTNode, Field, T, root_grammar_class
@@ -31,4 +34,4 @@ foo_grammar.add_rules(
     name=Name(Tok(Token.Identifier, keep=True)),
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/structs/field_override/test.out b/testsuite/tests/structs/field_override/test.out
index fe39bcdc4..d2b853d0e 100644
--- a/testsuite/tests/structs/field_override/test.out
+++ b/testsuite/tests/structs/field_override/test.out
@@ -1,4 +1,4 @@
-File "test.py", line 29, in Expr.name
+File "test.py", line 32, in Expr.name
     Error: "name" must be renamed as it conflicts with RootNode.p_name
 
 Done
diff --git a/testsuite/tests/structs/field_override/test.py b/testsuite/tests/structs/field_override/test.py
index 202f907a6..daea54488 100644
--- a/testsuite/tests/structs/field_override/test.py
+++ b/testsuite/tests/structs/field_override/test.py
@@ -2,6 +2,9 @@
 Test the handling of analysis units in the properties DSL.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import (
@@ -37,5 +40,5 @@ try:
     run()
 except DiagnosticError:
     pass
-print ''
-print 'Done'
+print('')
+print('Done')
diff --git a/testsuite/tests/structs/invalid_struct/test.out b/testsuite/tests/structs/invalid_struct/test.out
index 5a7e61504..a59fa369b 100644
--- a/testsuite/tests/structs/invalid_struct/test.out
+++ b/testsuite/tests/structs/invalid_struct/test.out
@@ -1,4 +1,4 @@
-File "test.py", line 21, in StructB
+File "test.py", line 24, in StructB
     Error: All Struct subclasses must directly derive from Struct itself
 
 Done
diff --git a/testsuite/tests/structs/invalid_struct/test.py b/testsuite/tests/structs/invalid_struct/test.py
index 0411234f8..24b46f031 100644
--- a/testsuite/tests/structs/invalid_struct/test.py
+++ b/testsuite/tests/structs/invalid_struct/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import (
     ASTNode, Field, LongType, Struct, root_grammar_class
 )
@@ -23,5 +26,5 @@ try:
 except DiagnosticError:
     pass
 
-print ''
-print 'Done'
+print('')
+print('Done')
diff --git a/testsuite/tests/structs/refcounted_fields/main.py b/testsuite/tests/structs/refcounted_fields/main.py
index e260900d6..b406fcd40 100644
--- a/testsuite/tests/structs/refcounted_fields/main.py
+++ b/testsuite/tests/structs/refcounted_fields/main.py
@@ -1,4 +1,7 @@
-print 'main.py: Running...'
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
+print('main.py: Running...')
 
 
 import sys
@@ -25,11 +28,11 @@ u.populate_lexical_env()
 name_lists = [name_list.p_to_struct
               for name_list in u.root.findall(libfoolang.ListDecl)]
 
-print 'Name lists:'
+print('Name lists:')
 for nl in name_lists:
-    print '  * {}: [{}]'.format(
+    print('  * {}: [{}]'.format(
         nl.f_label.f_tok.text,
         ', '.join(n.f_tok.text for n in nl.f_name_list)
-    )
+    ))
 
-print 'main.py: Done.'
+print('main.py: Done.')
diff --git a/testsuite/tests/structs/refcounted_fields/test.py b/testsuite/tests/structs/refcounted_fields/test.py
index a2064239d..3a576aee3 100644
--- a/testsuite/tests/structs/refcounted_fields/test.py
+++ b/testsuite/tests/structs/refcounted_fields/test.py
@@ -2,6 +2,9 @@
 Test that ref-counted fields in structs are properly bound in C/Python APIs.
 """
 
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import os.path
 
 from langkit.compiled_types import (
@@ -51,4 +54,4 @@ foo_grammar.add_rules(
     name=Name(Tok(Token.Identifier, keep=True)),
 )
 build_and_run(foo_grammar, 'main.py')
-print 'Done'
+print('Done')
diff --git a/testsuite/tests/structs/struct_env_spec/test.out b/testsuite/tests/structs/struct_env_spec/test.out
index 0817650b3..0b25e4c67 100644
--- a/testsuite/tests/structs/struct_env_spec/test.out
+++ b/testsuite/tests/structs/struct_env_spec/test.out
@@ -1,4 +1,4 @@
-File "test.py", line 17, in StructA
+File "test.py", line 20, in StructA
     Error: Structs cannot define lexical environment specifications
 
 Done
diff --git a/testsuite/tests/structs/struct_env_spec/test.py b/testsuite/tests/structs/struct_env_spec/test.py
index 52084e6c3..9ddcb3d98 100644
--- a/testsuite/tests/structs/struct_env_spec/test.py
+++ b/testsuite/tests/structs/struct_env_spec/test.py
@@ -1,3 +1,6 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 from langkit.compiled_types import ASTNode, Struct, root_grammar_class
 from langkit.diagnostics import DiagnosticError, Diagnostics
 from langkit.envs import EnvSpec
@@ -19,5 +22,5 @@ try:
 except DiagnosticError:
     pass
 
-print ''
-print 'Done'
+print('')
+print('Done')
diff --git a/testsuite/tests/stylechecks/test.py b/testsuite/tests/stylechecks/test.py
index 2f6980886..142360b32 100644
--- a/testsuite/tests/stylechecks/test.py
+++ b/testsuite/tests/stylechecks/test.py
@@ -1,2 +1,5 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
 import langkit.stylechecks
 langkit.stylechecks.localmain()