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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
+
+It is also possible to match requests by partial function, returning a response. E.g.::
+
+  implicit val testingBackend = SttpBackendStub(HttpURLConnectionBackend())
+    .whenRequestMatchesPartial({
+      case r if r.uri.path.endsWith(List("partial10")) => Response(Right(10), 200, Nil, Nil)
+      case r if r.uri.path.endsWith(List("partialAda")) => Response(Right("Ada"), 200, Nil, Nil)
+    })
+
+  val response1 = sttp.get(uri"http://example.org/partial10").send()
+  // response1.body will be Right(10)
+
+  val response2 = sttp.post(uri"http://example.org/partialAda").send()
+  // response2.body will be Right("Ada")
+
+This approach to testing 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.
+
+Simulating exceptions
+---------------------
+
+If you want to simulate an exception being thrown by a backend, e.g. a socket timeout exception, you can do so by throwing the appropriate exception instead of the response, e.g.::
+
+  implicit val testingBackend = SttpBackendStub(HttpURLConnectionBackend())
+    .whenRequestMatches(_ => true)
+    .thenRespond(throw new TimeoutException())
+
+Adjusting the response body type
+--------------------------------
+
+If the type of the response body returned by the stub's rules (as specified using the ``.whenXxx`` methods) doesn't match what was specified in the request, the stub will attempt to convert the body to the desired type. This might be useful when:
+
+* testing code which maps a basic response body to a custom type, e.g. mapping a raw json string using a decoder to a domain type
+* reading a classpath resource (which results in an ``InputStream``) and requesting a response of e.g. type ``String``
+
+The following conversions are supported:
+
+* anything to ``()`` (unit), when the response is ignored
+* ``InputStream`` and ``Array[Byte]`` to ``String``
+* ``InputStream`` and ``String`` to ``Array[Byte]``
+* ``InputStream``, ``String`` and ``Array[Byte]`` to custom types through mapped response specifications
+
+For example::
+
+  implicit val testingBackend = SttpBackendStub(HttpURLConnectionBackend())
+    .whenRequestMatches(_ => true)
+    .thenRespond(""" {"username": "john", "age": 65 } """)
+
+  def parseUserJson(a: Array[Byte]): User = ...
+
+  val response = sttp.get(uri"http://example.com")
+    .response(asByteArray.map(parseUserJson))
+    .send()
+
+In the example above, the stub's rules specify that a response with a ``String``-body should be returned for any request; the request, on the other hand, specifies that responses should be parsed from a byte array to a custom ``User`` type. These type don't match, so the ``SttpBackendStub`` will in this case convert the body to the desired type.
+
+Note that no conversions will be attempted for streaming response bodies.
+
+Delegating to another backend
+-----------------------------
+
+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
+