Handle $RESPONSE templates in the current response

In some APIs it is useful to refer to the response of a previous
request in the response of this current request to, for example,
verify that an ID continues to be used.

Up to now $RESPONSE handling worked in url and data, this change
adds it to response_strings and response_json_paths.

As with all of the $RESPONSE handling, this is power that should
really only be used when testing existing APIs. If you need a lot of
this when you are developing new APIs YOU ARE DOING IT WRONG.

gabbi/case.py

@@ -78,6 +78,7 @@ def _assert_response(self, response, content, status, headers=None,
         # Compare strings in response body
         if expected:
             for expect in expected:
+                expect = self._replace_response_values(expect)
                 self.assertIn(expect, decoded_output)
 
         # Decode body as JSON and test against json_paths
@@ -86,9 +87,9 @@ def _assert_response(self, response, content, status, headers=None,
             self.json_data = response_data
             for path in json_paths:
                 match = self._extract_json_path_value(response_data, path)
-                self.assertEqual(json_paths[path], match,
-                                 'Unable to match %s as %s'
-                                 % (path, json_paths[path]))
+                expected = self._replace_response_values(json_paths[path])
+                self.assertEqual(expected, match, 'Unable to match %s as %s'
+                                 % (path, expected))
 
     def _decode_content(self, response, content):
         """Decode content to a proper string."""
@@ -171,7 +172,11 @@ def _replacer(self, match):
 
     def _replace_response_values(self, template):
         """Replace a JSON Path in a template string with its value."""
-        return re.sub(r"\$RESPONSE\['([^']+)'\]", self._replacer, template)
+        try:
+            return re.sub(r"\$RESPONSE\['([^']+)'\]", self._replacer, template)
+        except TypeError:
+            # template is not a string
+            return template
 
     def _run_test(self):
         """Make an HTTP request and compare the response with expectations."""

gabbi/gabbits_intercept/backref.yaml

@@ -20,12 +20,25 @@ tests:
   request_headers:
       content-type: application/json
   method: POST
-  data: |
-     {"a": $RESPONSE['a'],
-      "c": "$RESPONSE['link']"}
-
+  data:
+     a: $RESPONSE['a']
+     c: $RESPONSE['link']
   response_json_paths:
-     a: 1
+     a: $RESPONSE['a']
      c: /v2
   response_headers:
      x-gabbi-url: $SCHEME://$NETLOC/v2
+
+- name: post even more json
+  url: $RESPONSE['c']
+  request_headers:
+      content-type: application/json
+  method: POST
+  data: |
+      {"a": "$RESPONSE['a']",
+       "c": "$RESPONSE['c']"}
+  response_strings:
+      - '"a": "$RESPONSE[''a'']"'
+      - '"c": "/v2"'
+  response_headers:
+     x-gabbi-url: $SCHEME://$NETLOC/v2