Bug 979640 - Make build system error on missing test files; r=ted

Previously, the build system may silently missing test files defined in
manifests. This patch makes missing test files a fatal error, detected
when reading test manifests.

The test_bug872273.html XBL test appeared to be orphaned in
content/xbl/test. It has been reunited with its family.

dom/tests/mochitest/notification referenced a single test file which was
recently deleted. That manifest has been removed.

Missing test files related to the Python unit tests for the build system
have been added. (They are a bunch of empty files.)

python/mozbuild/mozbuild/frontend/emitter.py

@@ -476,7 +476,16 @@ class TreeMetadataEmitter(LoggingMixin):
             filtered = m.tests
 
             if filter_inactive:
-                filtered = m.active_tests(disabled=False, **self.mozinfo)
+                # We return tests that don't exist because we want manifests
+                # defining tests that don't exist to result in error.
+                filtered = m.active_tests(exists=False, disabled=False,
+                    **self.mozinfo)
+
+                missing = [t['name'] for t in filtered if not os.path.exists(t['path'])]
+                if missing:
+                    raise SandboxValidationError('Test manifest (%s) lists '
+                        'test that does not exist: %s' % (
+                        path, ', '.join(missing)))
 
             out_dir = mozpath.join(install_prefix, manifest_reldir)
 

python/mozbuild/mozbuild/test/frontend/data/test-manifest-missing-test-file/mochitest.ini

@@ -0,0 +1 @@
+[test_missing.html]

python/mozbuild/mozbuild/test/frontend/data/test-manifest-missing-test-file/moz.build

@@ -0,0 +1,4 @@
+# Any copyright is dedicated to the Public Domain.
+# http://creativecommons.org/publicdomain/zero/1.0/
+
+MOCHITEST_MANIFESTS += ['mochitest.ini']

python/mozbuild/mozbuild/test/frontend/test_emitter.py

@@ -476,6 +476,14 @@ class TestEmitterBasic(unittest.TestCase):
         self.assertEqual(o.installs[expected],
             ('testing/mochitest/tests/child/support-file.txt', False))
 
+    def test_test_manifest_missing_test_error(self):
+        """Missing test files should result in error."""
+        reader = self.reader('test-manifest-missing-test-file')
+
+        with self.assertRaisesRegexp(SandboxValidationError,
+            'lists test that does not exist: test_missing.html'):
+            self.read_topsrcdir(reader)
+
     def test_ipdl_sources(self):
         reader = self.reader('ipdl_sources')
         objs = self.read_topsrcdir(reader)