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+Testing
+=======
+
+If you need a stub backend for use in tests instead of a "real" backend (you 
+probably don't want to make HTTP calls during unit tests), you can use the
+``SttpBackendStub`` class. It allows specifying how the backend should respond
+to requests matching given predicates.
+
+A backend stub can be created using an instance of a "real" backend, or by
+explicitly giving the response wrapper monad and supported streams type.
+
+For example::
+
+  implicit val testingBackend = SttpBackendStub(HttpURLConnectionBackend())
+    .whenRequestMatches(_.uri.path.startsWith(List("a", "b")))
+    .thenRespond("Hello there!")
+    .whenRequestMatches(_.method == Method.POST)
+    .thenRespondServerError()
+      
+  val response1 = sttp.get(uri"http://example.org/a/b/c").send()
+  // response1.body will be Right("Hello there")
+  
+  val response2 = sttp.post(uri"http://example.org/d/e").send()
+  // response2.code will be 500
+
+However, this approach has one caveat: the responses are not type-safe. That
+is, the backend cannot match on or verify that the type included in the 
+response matches the response type requested.
+
+It is also possible to create a stub backend which delegates calls to another
+(possibly "real") backend if none of the specified predicates match a request.
+This can be useful during development, to partially stub a yet incomplete
+API with which we integrate::
+
+  implicit val testingBackend = SttpBackendStub.withFallback(HttpURLConnectionBackend())
+    .whenRequestMatches(_.uri.path.startsWith(List("a")))
+    .thenRespond("I'm a STUB!")
+      
+  val response1 = sttp.get(uri"http://api.internal/a").send()
+  // response1.body will be Right("I'm a STUB")
+  
+  val response2 = sttp.post(uri"http://api.internal/b").send()
+  // response2 will be whatever a "real" network call to api.internal/b returns
+