From e695c37151c84d43e1a37719cc1bbf3fc8366ddb Mon Sep 17 00:00:00 2001 From: adamw Date: Mon, 13 Nov 2017 15:43:11 +0100 Subject: Improving testing docs --- docs/backends/testing.rst | 93 ----------------------------------------------- 1 file changed, 93 deletions(-) delete mode 100644 docs/backends/testing.rst (limited to 'docs/backends') diff --git a/docs/backends/testing.rst b/docs/backends/testing.rst deleted file mode 100644 index d082f40..0000000 --- a/docs/backends/testing.rst +++ /dev/null @@ -1,93 +0,0 @@ -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 request 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") - -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. - -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 ``.when...`` 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 - -- cgit v1.2.3