init: Add validation for module defaults

After cloning the repository with defaults, open each file and try to
check if there is more than one definition for the same module. It's not
a problem for the compose process, but consumers of the compose would
get confused and possibly explode. Better alert people early.

Conceptually this should be part of the test phase, but that would mean
waiting for the compose to finish before reporting the error. The
earlier the better.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/test_initphase.py

@@ -10,6 +10,7 @@ import sys
 
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
 
+from pungi import Modulemd
 from pungi.phases import init
 from tests.helpers import DummyCompose, PungiTestCase, touch
 
@@ -333,5 +334,66 @@ class TestWriteVariantComps(PungiTestCase):
         self.assertEqual(comps.write_comps.mock_calls, [])
 
 
+@unittest.skipUnless(Modulemd, "Skipped test, no module support.")
+class TestValidateModuleDefaults(PungiTestCase):
+
+    def _write_defaults(self, defs):
+        for mod_name, streams in defs.items():
+            for stream in streams:
+                mmddef = Modulemd.Defaults.new()
+                mmddef.set_version(1)
+                mmddef.set_module_name(mod_name)
+                mmddef.set_default_stream(stream)
+                mmddef.dump(
+                    os.path.join(self.topdir, "%s-%s.yaml" % (mod_name, stream))
+                )
+
+    def test_valid_files(self):
+        self._write_defaults({"httpd": ["1"], "python": ["3.6"]})
+
+        init.validate_module_defaults(self.topdir)
+
+    def test_duplicated_stream(self):
+        self._write_defaults({"httpd": ["1"], "python": ["3.6", "3.5"]})
+
+        with self.assertRaises(RuntimeError) as ctx:
+            init.validate_module_defaults(self.topdir)
+
+        self.assertIn(
+            "Module python has multiple defaults: 3.5, 3.6", str(ctx.exception)
+        )
+
+    def test_reports_all(self):
+        self._write_defaults({"httpd": ["1", "2"], "python": ["3.6", "3.5"]})
+
+        with self.assertRaises(RuntimeError) as ctx:
+            init.validate_module_defaults(self.topdir)
+
+        self.assertIn("Module httpd has multiple defaults: 1, 2", str(ctx.exception))
+        self.assertIn(
+            "Module python has multiple defaults: 3.5, 3.6", str(ctx.exception)
+        )
+
+    def test_handles_non_defaults_file(self):
+        self._write_defaults({"httpd": ["1"], "python": ["3.6"]})
+        touch(
+            os.path.join(self.topdir, "boom.yaml"),
+            "\n".join(
+                [
+                    "document: modulemd",
+                    "version: 2",
+                    "data:",
+                    "  summary: dummy module",
+                    "  description: dummy module",
+                    "  license:",
+                    "    module: [GPL]",
+                    "    content: [GPL]",
+                ]
+            ),
+        )
+
+        init.validate_module_defaults(self.topdir)
+
+
 if __name__ == "__main__":
     unittest.main()