Add URL recipe module from "depot_tools".

recipe_modules/url/test_api.py

Index: recipe_modules/url/test_api.py
diff --git a/recipe_modules/url/test_api.py b/recipe_modules/url/test_api.py
new file mode 100644
index 0000000000000000000000000000000000000000..8aa734e4e306d7b6f21ea0631ac29f487437d467
--- /dev/null
+++ b/recipe_modules/url/test_api.py
@@ -0,0 +1,48 @@
+# Copyright 2017 The LUCI Authors. All rights reserved.
+# Use of this source code is governed under the Apache License, Version 2.0
+# that can be found in the LICENSE file.
+
+import httplib
+
+from recipe_engine import recipe_test_api
+
+
+class UrlTestApi(recipe_test_api.RecipeTestApi): # pragma: no cover
+
+  def _response(self, step_name, data, size, status_code, error_body):
+    step_data = [
+        self.m.json.output({
+          'status_code': status_code,
+          'success': status_code in (httplib.OK, httplib.NO_CONTENT),
+          'size': size,
+          'error_body': error_body,
+        }, name='status_json'),
+    ]
+    if data:
+      step_data.append(data)
+    return self.step_data(step_name, *step_data)
+
+  def error(self, step_name, status_code, body=None):
+    body = body or 'HTTP Error (%d)' % (status_code,)
+    return self._response(
+        step_name,
+        None,
+        len(body),
+        status_code,
+        body)
+
+  def text(self, step_name, v):
+    return self._response(
+        step_name,
+        self.m.raw_io.output_text(v, name='output'),
+        len(v),
+        200,
+        None)
+
+  def json(self, step_name, obj):
+    return self._response(
+        step_name,
+        self.m.json.output(obj, name='output'),
+        len(self.m.json.dumps(obj)),
+        200,
+        None)