Update tests for fail-fast DISTRO behavior and ubuntu codename mapping

Author: ofiryanai

test_module_metadata.py

@@ -18,16 +18,35 @@ def test_uses_devcontainer_distro_before_host_distro(self):
                     with mock.patch.object(module_metadata.distro, "version_parts", return_value=("8",)):
                         self.assertEqual(module_metadata.get_curr_os(), "amzn2023")
 
-    def test_falls_back_to_distro_when_devcontainer_has_no_distro(self):
+    def test_raises_when_devcontainer_has_no_distro(self):
         with tempfile.TemporaryDirectory() as temp_dir:
             devcontainer_path = os.path.join(temp_dir, "devcontainer")
             with open(devcontainer_path, "w") as f:
                 f.write("OTHER=value\n")
 
             with mock.patch.object(module_metadata, "DEVCONTAINER_PATH", devcontainer_path):
-                with mock.patch.object(module_metadata.distro, "id", return_value="rocky"):
-                    with mock.patch.object(module_metadata.distro, "version_parts", return_value=("8",)):
-                        self.assertEqual(module_metadata.get_curr_os(), "rhel8")
+                with self.assertRaises(KeyError):
+                    module_metadata.get_curr_os()
+
+    def test_maps_ubuntu_codenames_to_versions(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            for distro_value, expected in (("focal", "ubuntu20"), ("jammy", "ubuntu22")):
+                devcontainer_path = os.path.join(temp_dir, "devcontainer")
+                with open(devcontainer_path, "w") as f:
+                    f.write("DISTRO=%s\n" % distro_value)
+
+                with mock.patch.object(module_metadata, "DEVCONTAINER_PATH", devcontainer_path):
+                    self.assertEqual(module_metadata.get_curr_os(), expected)
+
+    def test_amzn2023_unchanged_but_jammy_mapped_to_ubuntu22(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            for distro_value, expected in (("amzn2023", "amzn2023"), ("jammy", "ubuntu22")):
+                devcontainer_path = os.path.join(temp_dir, "devcontainer")
+                with open(devcontainer_path, "w") as f:
+                    f.write("DISTRO=%s\n" % distro_value)
+
+                with mock.patch.object(module_metadata, "DEVCONTAINER_PATH", devcontainer_path):
+                    self.assertEqual(module_metadata.get_curr_os(), expected)
 
     def test_preserves_distro_fallback_when_devcontainer_is_absent(self):
         devcontainer_path = os.path.join(tempfile.gettempdir(), "missing-devcontainer")