1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
|
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
|
