diff --git a/.gitignore b/.gitignore
index 45013b9e..cab0b726 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,6 +4,7 @@ conf.json*
 
 # auto created when running on desktop:
 internal_filesystem/SDLPointer_2
+internal_filesystem/SDLPointer_3
 
 # config files etc:
 internal_filesystem/data
diff --git a/internal_filesystem/lib/README.md b/internal_filesystem/lib/README.md
index 1c149121..fe3eabff 100644
--- a/internal_filesystem/lib/README.md
+++ b/internal_filesystem/lib/README.md
@@ -7,4 +7,5 @@ This /lib folder contains:
 - mip.install("aiohttp") # easy websockets
 - mip.install("base64") # for nostr etc
 - mip.install("collections") # used by aiohttp
+- mip.install("unittest")
 
diff --git a/internal_filesystem/lib/mpos/content/package_manager.py b/internal_filesystem/lib/mpos/content/package_manager.py
index 114b5c19..60aa365e 100644
--- a/internal_filesystem/lib/mpos/content/package_manager.py
+++ b/internal_filesystem/lib/mpos/content/package_manager.py
@@ -166,8 +166,12 @@ class PackageManager:
         """Compare two version numbers (e.g., '1.2.3' vs '4.5.6').
         Returns True if ver1 is greater than ver2, False otherwise."""
         print(f"Comparing versions: {ver1} vs {ver2}")
-        v1_parts = [int(x) for x in ver1.split('.')]
-        v2_parts = [int(x) for x in ver2.split('.')]
+        try:
+            v1_parts = [int(x) for x in ver1.split('.')]
+            v2_parts = [int(x) for x in ver2.split('.')]
+        except ValueError as e:
+            print(f"Invalid input, got error: {e}")
+            return False
         print(f"Version 1 parts: {v1_parts}")
         print(f"Version 2 parts: {v2_parts}")
         for i in range(max(len(v1_parts), len(v2_parts))):
diff --git a/internal_filesystem/lib/unittest/__init__.mpy b/internal_filesystem/lib/unittest/__init__.mpy
new file mode 100644
index 00000000..ce71760c
Binary files /dev/null and b/internal_filesystem/lib/unittest/__init__.mpy differ
diff --git a/tests/package_manager.py b/tests/package_manager.py
new file mode 100644
index 00000000..6204e994
--- /dev/null
+++ b/tests/package_manager.py
@@ -0,0 +1,37 @@
+import unittest
+
+from mpos import PackageManager
+
+class TestCompareVersions(unittest.TestCase):
+
+    def test_lower_short(self):
+        self.assertFalse(PackageManager.compare_versions("1" , "4"))
+
+    def test_lower(self):
+        self.assertFalse(PackageManager.compare_versions("1.2.3" , "4.5.6"))
+
+    def test_equal(self):
+        self.assertFalse(PackageManager.compare_versions("1.2.3" , "1.2.3"))
+
+    def test_higher(self):
+        self.assertTrue(PackageManager.compare_versions("4.5.6", "1.2.3"))
+    
+    def test_higher_medium_and_long(self):
+        self.assertTrue(PackageManager.compare_versions("4.5", "1.2.3"))
+    
+    def test_words(self):
+        self.assertFalse(PackageManager.compare_versions("weird" , "input"))
+
+    def test_one_empty(self):
+        self.assertFalse(PackageManager.compare_versions("1.2.3" , ""))
+
+class TestPackageManager_is_installed_by_name(unittest.TestCase):
+
+    def test_installed_builtin(self):
+        self.assertTrue(PackageManager.is_installed_by_name("com.micropythonos.appstore"))
+
+    def test_installed_not_builtin(self):
+        self.assertTrue(PackageManager.is_installed_by_name("com.micropythonos.helloworld"))
+
+    def test_not_installed(self):
+        self.assertFalse(PackageManager.is_installed_by_name("com.micropythonos.badname"))
diff --git a/tests/simple.py b/tests/simple.py
new file mode 100644
index 00000000..35437d1e
--- /dev/null
+++ b/tests/simple.py
@@ -0,0 +1,6 @@
+import unittest
+
+class TestMath(unittest.TestCase):
+    def test_add(self):
+        self.assertEqual(1 + 1, 2)
+
diff --git a/tests/tests/check_syntax.sh b/tests/tests/check_syntax.sh
new file mode 100755
index 00000000..62c9623c
--- /dev/null
+++ b/tests/tests/check_syntax.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+mydir=$(readlink -f "$0")
+mydir=$(dirname "$mydir")
+fs="$mydir"/../../internal_filesystem/
+cross="$mydir"/../../lvgl_micropython/lib/micropython/mpy-cross/build/mpy-cross
+
+failed=0
+while read file; do
+	"$cross" -march=x64 -o /dev/null  "$file"
+	exitcode="$?"
+	if [ $exitcode -ne 0 ]; then
+		echo "$file got exitcode $exitcode"
+		failed=$(expr $failed \+ 1)
+	fi
+done < <(find "$fs" -iname "*.py")
+
+if [ $failed -ne 0 ]; then
+	echo "ERROR: $failed .py files have syntax errors"
+	exit 1
+fi
diff --git a/tests/unittest.sh b/tests/unittest.sh
new file mode 100755
index 00000000..d3a59f95
--- /dev/null
+++ b/tests/unittest.sh
@@ -0,0 +1,63 @@
+#!/bin/bash
+
+mydir=$(readlink -f "$0")
+mydir=$(dirname "$mydir")
+testdir="$mydir"
+scriptdir=$(readlink -f "$mydir"/../scripts/)
+fs="$mydir"/../internal_filesystem/
+onetest="$1"
+
+
+# print os and set binary
+os_name=$(uname -s)
+if [ "$os_name" = "Darwin" ]; then
+        echo "Running on macOS"
+        binary="$scriptdir"/../lvgl_micropython/build/lvgl_micropy_macOS
+else
+        # other cases can be added here
+        echo "Running on $os_name"
+        binary="$scriptdir"/../lvgl_micropython/build/lvgl_micropy_unix
+fi
+
+one_test() {
+	file="$1"
+	pushd "$fs"
+	echo "Testing $file"
+	"$binary" -X heapsize=8M -c "import sys ; sys.path.append('lib') 
+$(cat $file)
+result = unittest.main() ; sys.exit(0 if result.wasSuccessful() else 1) "
+	result=$?
+	popd
+	return "$result"
+}
+
+failed=0
+
+if [ -z "$onetest" ]; then
+	echo "Usage: $0 [one_test_to_run.py]"
+	echo "Example: $0 tests/simple.py"
+	echo
+	echo "If no test is specified: run all tests from $testdir"
+	while read file; do
+		one_test "$file"
+		result=$?
+		if [ $result -ne 0 ]; then
+			echo "test $file got error $result"
+			failed=$(expr $failed \+ 1)
+		fi
+
+	done < <( find "$testdir" -iname "*.py" )
+else
+	one_test $(readlink -f "$onetest")
+	[ $? -ne 0 ] && failed=1
+fi
+
+
+if [ $failed -ne 0 ]; then
+        echo "ERROR: $failed .py files have failing unit tests"
+        exit 1
+else
+	echo "GOOD: no .py files have failing unit tests"
+	exit 0
+fi
+