[test] Test update_checkout --dump-hashes output

Author: porglezomp

utils/update_checkout/tests/scheme_mock.py

@@ -78,7 +78,7 @@ def __str__(self):
 def call_quietly(*args, **kwargs):
     kwargs['stderr'] = subprocess.STDOUT
     try:
-        subprocess.check_output(*args, **kwargs)
+        return subprocess.check_output(*args, **kwargs)
     except subprocess.CalledProcessError as e:
         raise CallQuietlyException(command=e.cmd, returncode=e.returncode,
                                    output=e.stdout) from e
@@ -180,7 +180,7 @@ def tearDown(self):
 
     def call(self, *args, **kwargs):
         kwargs['cwd'] = self.source_root
-        call_quietly(*args, **kwargs)
+        return call_quietly(*args, **kwargs)
 
     def get_all_repos(self):
         return list(self.config["repos"].keys())

utils/update_checkout/tests/test_dump.py

@@ -10,6 +10,8 @@
 #
 # ===----------------------------------------------------------------------===#
 
+import json
+
 from . import scheme_mock
 
 
@@ -25,9 +27,16 @@ def test_dump_hashes_json(self):
                    '--source-root', self.source_root,
                    '--clone'])
 
-        # Then dump the hashes. Just make sure we don't crash. We should test
-        # the output as well. But we should never crash.
-        self.call([self.update_checkout_path,
-                   '--config', self.config_path,
-                   '--source-root', self.source_root,
-                   '--dump-hashes'])
+        # Then dump the hashes.
+        output = self.call([self.update_checkout_path,
+                            '--config', self.config_path,
+                            '--source-root', self.source_root,
+                            '--dump-hashes'])
+        # The output should be valid JSON
+        result = json.loads(output)
+
+        # And it should have some basic properties we expect from this JSON
+        self.assertIn("https-clone-pattern", result)
+        self.assertEqual(result["repos"], scheme_mock.MOCK_CONFIG["repos"])
+        self.assertEqual(result["ssh-clone-pattern"], "DO_NOT_USE")
+        self.assertSetEqual(set(result["branch-schemes"].keys()), {"repro"})