Attempt to fix tests

tools/wpt/tests/test_wpt.py

@@ -30,27 +30,29 @@ def is_port_8000_in_use():
     return False
 
 
-@pytest.fixture(scope="module")
+def get_persistent_manifest_path():
+    directory = ("~/meta" if os.environ.get('TRAVIS') == "true"
+                 else wpt.localpaths.repo_root)
+    return os.path.join(directory, "MANIFEST.json")
+
+
+@pytest.fixture(scope="module", autouse=True)
+def init_manifest():
+    with pytest.raises(SystemExit) as excinfo:
+        wpt.main(argv=["manifest", "--no-download",
+                       "--path", get_persistent_manifest_path()])
+    assert excinfo.value.code == 0
+
+
+@pytest.fixture
 def manifest_dir():
-    def update_manifest():
-        with pytest.raises(SystemExit) as excinfo:
-            wpt.main(argv=["manifest", "--no-download", "--path", os.path.join(path, "MANIFEST.json")])
-        assert excinfo.value.code == 0
-
-    if os.environ.get('TRAVIS') == "true":
-        path = "~/meta"
-        update_manifest()
+    try:
+        path = tempfile.mkdtemp()
+        shutil.copyfile(get_persistent_manifest_path(),
+                        os.path.join(path, "MANIFEST.json"))
         yield path
-    else:
-        try:
-            path = tempfile.mkdtemp()
-            old_path = os.path.join(wpt.localpaths.repo_root, "MANIFEST.json")
-            if os.path.exists(os.path.join(wpt.localpaths.repo_root, "MANIFEST.json")):
-                shutil.copyfile(old_path, os.path.join(path, "MANIFEST.json"))
-            update_manifest()
-            yield path
-        finally:
-            shutil.rmtree(path)
+    finally:
+        shutil.rmtree(path)
 
 
 @pytest.fixture
@@ -91,7 +93,6 @@ def test_help():
     assert excinfo.value.code == 0
 
 
-@pytest.mark.slow
 @pytest.mark.xfail(sys.platform == "win32",
                    reason="https://github.com/web-platform-tests/wpt/issues/12935")
 def test_list_tests(manifest_dir):