Add a testcase for EquationType binding in the Python API

TN: Q221-031

testsuite/tests/python-api/equation_type/main.py

@@ -0,0 +1,21 @@
+from __future__ import (absolute_import, division, print_function,
+                        unicode_literals)
+
+print('main.py: Running...')
+
+
+import sys
+
+import libfoolang
+
+
+ctx = libfoolang.AnalysisContext()
+u = ctx.get_from_buffer('foo.txt', 'example')
+if u.diagnostics:
+    for d in u.diagnostics:
+        print(d)
+    sys.exit(1)
+
+u.populate_lexical_env()
+print('u.root.p_eq(None) = {}'.format(u.root.p_eq(None)))
+print('main.py: Done.')

testsuite/tests/python-api/equation_type/test.out

@@ -0,0 +1,4 @@
+main.py: Running...
+u.root.p_eq(None) = None
+main.py: Done.
+Done

testsuite/tests/python-api/equation_type/test.py

@@ -0,0 +1,41 @@
+"""
+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 (
+    ASTNode, EquationType, Field, Token as TokenType, root_grammar_class
+)
+from langkit.diagnostics import Diagnostics
+from langkit.expressions import langkit_property
+from langkit.parsers import Grammar, Tok
+
+from lexer_example import Token
+from utils import build_and_run
+
+
+Diagnostics.set_lang_source_dir(os.path.abspath(__file__))
+
+
+@root_grammar_class()
+class FooNode(ASTNode):
+    @langkit_property(public=True, return_type=EquationType)
+    def eq(eq=EquationType):
+        return eq
+
+
+class Example(FooNode):
+    tok = Field(type=TokenType)
+
+
+foo_grammar = Grammar('main_rule')
+foo_grammar.add_rules(
+    main_rule=Example(Tok(Token.Example, keep=True)),
+)
+build_and_run(foo_grammar, 'main.py')
+print('Done')

testsuite/tests/python-api/equation_type/test.yaml

@@ -0,0 +1 @@
+driver: python