Add example and documentation for request-hash.

Author: nickpresta

README.md

@@ -43,6 +43,18 @@ The directory `httpbin` must already exist before running.
 
 See `chameleon -help` for more information.
 
+### Specifying custom hash
+
+There may be a reason in your tests to manually create responses - perhaps the backing service doesn't exist yet, or in test mode a service behaves differently than production. When this is the case, you can create custom responses and signal to chameleon the hash you want to use for a given request.
+
+Set the `chameleon-request-hash` header with a unique hash value (which is a valid filename) and chameleon will look for that hash in the `spec.json` file and for all subsequent requests.
+
+This allows you to not only have total control over the response for a given request but also makes your test code easier to reason about -- it is clear where the "special case" response is coming from.
+
+### Getting the hash for a given request
+
+All responses from chameleon will have a `chameleon-request-hash` header set which is the hash used for that request. This header is present even if you did not set it on the incoming request.
+
 ### Preseeding the cache
 
 If you want to configure the cache at runtime without having to depend on an external service, you may preseed the cache

example/app.py

@@ -86,6 +86,23 @@ def do_SEEDED(self):
         self.end_headers()
         self.wfile.write(resp.read())
 
+    def do_REQUESTHASH(self):
+        content_len = int(self.headers.getheader('content-length', 0))
+        body = self.rfile.read(content_len)
+
+        req = urllib2.Request(POST_SERVICE_URL, body, self.headers)
+        req.get_method = lambda: 'POST'
+        try:
+            resp = urllib2.urlopen(req)
+        except urllib2.HTTPError as exc:
+            resp = exc
+
+        self.send_response(200)
+        for k, v in resp.headers.dict.viewitems():
+            self.send_header(k, v)
+        self.end_headers()
+        self.wfile.write(resp.read())
+
 
 def main():
     print('Serving on port {}'.format(TEST_APP_PORT))

example/testing_data/foo_bar_hash

@@ -0,0 +1,20 @@
+{
+  "args": {}, 
+  "data": "{\"foo\": \"bar\"}", 
+  "files": {}, 
+  "form": {}, 
+  "headers": {
+    "Accept-Encoding": "identity", 
+    "Chameleon-Request-Hash": "foo_bar_hash", 
+    "Content-Length": "14", 
+    "Content-Type": "application/json", 
+    "Host": "httpbin.org", 
+    "User-Agent": "Python-urllib/2.7", 
+    "X-Forwarded-Ssl": "on"
+  }, 
+  "json": {
+    "foo": "bar"
+  }, 
+  "origin": "99.245.54.15", 
+  "url": "http://httpbin.org/post"
+}

example/testing_data/spec.json

@@ -110,5 +110,20 @@
             }
         },
         "key": "9835adf25e3ecc09431cdf3079bb822a"
+    },
+    {
+        "response": {
+            "status_code": 200,
+            "content": "foo_bar_hash",
+            "headers": {
+                "Access-Control-Allow-Credentials": "true",
+                "Access-Control-Allow-Origin": "*",
+                "Content-Length": "452",
+                "Content-Type": "application/json",
+                "Date": "Sun, 18 Jan 2015 23:30:57 GMT",
+                "Server": "nginx"
+            }
+        },
+        "key": "foo_bar_hash"
     }
 ]

example/tests.py

@@ -109,6 +109,17 @@ def test_preseed(self):
         self.assertEqual(942, resp.getcode())
         self.assertEqual({'key': 'value'}, json.loads(resp.read()))
 
+    def test_specify_hash_in_request(self):
+        url = 'http://localhost:{}/post'.format(TEST_APP_PORT)
+        req = urllib2.Request(url, json.dumps({'foo': 'bar'}), {
+            'Content-type': 'application/json', 'chameleon-request-hash': 'foo_bar_hash'})
+        req.get_method = lambda: 'REQUESTHASH'
+        resp = urllib2.urlopen(req)
+        content = resp.read()
+        parsed = json.loads(content)
+        self.assertEqual({'foo': 'bar'}, parsed['json'])
+        self.assertEqual('foo_bar_hash', resp.headers['chameleon-request-hash'])
+
 
 if __name__ == '__main__':
     unittest.main()

handlers.go

@@ -91,7 +91,6 @@ func CachedProxyHandler(serverURL *url.URL, cacher Cacher, hasher Hasher) http.H
 
 		hash := r.Header.Get("chameleon-request-hash")
 		if hash == "" {
-			log.Printf("-> Hashing Request %v", r.URL)
 			hash = hasher.Hash(r)
 		}
 		response := cacher.Get(hash)