Changed mach test to use generated json file of properties

components/style/list_properties.py

@@ -23,7 +23,6 @@
 )
 
 json_dump = json.dumps(properties, indent=4)
-print(json_dump)
 
 #
 # Resolve path to doc directory and write CSS properties and JSON.

python/servo/testing_commands.py

@@ -163,10 +163,17 @@ def test(self, params, render_mode=DEFAULT_RENDER_MODE, release=False, faster=Fa
     @CommandArgument('test_name', nargs=argparse.REMAINDER,
                      help="Only run tests that match this pattern or file path")
     def test_unit(self, test_name=None, package=None):
-        properties = json.loads(subprocess.check_output([
+        subprocess.check_output([
             sys.executable,
             path.join(self.context.topdir, "components", "style", "list_properties.py")
-        ]))
+        ])
+
+        this_file = style = os.path.dirname(__file__)
+        servo_doc_path = os.path.abspath(os.path.join(this_file, '../', '../', 'target', 'doc', 'servo'))
+
+        with open(os.path.join(servo_doc_path, 'css-properties.json'), 'r') as property_file:
+            properties = json.loads(property_file.read())
+
         assert len(properties) >= 100
         assert "margin-top" in properties
         assert "margin" in properties