assert-rx

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Language
Java
Version
0.9.8 (Oct 31, 2016)
Created
Jun 19, 2016
Updated
Nov 11, 2016 (Retired)
Owner
Peter Tackage (peter-tackage)
Contributor
Peter Tackage (peter-tackage)
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Assert-Rx

DEPRECATED!

As of RxJava 1.3, fluent assertions will be part of the RxJava 1.x library. You should use the official equivalent instead. The official assertions are assertion library agnostic and use the same API as RxJava 2.x, which should help you make the transition should you chose to.

Only use this library if somehow you cannot to update to RxJava 1.3.

Every library has its lifespan and this one's has ended. Thank you for your interest!

A fluent assertion wrapper to simplify and improve usability of RxJava's TestSubscriber assertions, built upon the AssertJ framework.

Purpose

Although TestSubscriber provides some very handy assertions to test your Observables, it can be a bit tedious and verbose to use. For example, to test the last value in a sequence you would typically write:

   TestSubscriber<String> ts = ...... // subscribe to your Observable with TestSubscriber

   ts.assertNoErrors();
   List<String> values = ts.getOnNextEvents();
   assertThat(values.get(values.size() - 1)).isEqualTo("expectedValue");

This library makes this more readable by allowing you to express assertions in a fluent style:

   TestSubscriber<String> ts = ...... // subscribe to your Observable with TestSubscriber

   assertThat(ts).hasNoErrors()
                 .hasReceivedLastValue("expectedValue");

In addition to this wrapping, it provides some higher order assertions to allow for testing of specific conditions.

    assertThat(ts).hasReceivedFirstValueWhich()
                  .is(notEmptyOrNull());

Where notEmptyOrNull is a reusable, AssertJ Condition.

Usage

Here are a few examples of the assertions performed using Assert-Rx.

OnNext Assertions

Assert that the subscriber received any single onNext value:

    assertThat(ts).hasReceivedAnyValue();

Assert that the subscriber has received one or more onNext values:

    assertThat(ts).hasReceivedAnyValues();

Multiple, in-order values:

    assertThat(ts).hasReceivedValues("a", "b", "c");

Assert conditions for single onNext events (currently only as Object instances):

    assertThat(ts).hasReceivedValueWhich()
                  .is(notEmptyOrNull());

Assert conditions for the entire onNext value sequence:

    assertThat(ts).hasReceivedValuesWhich()
                  .doesNotContain(someObject);

Assert the first or last received onNext values:

    assertThat(ts).hasReceivedFirstValue("the first value");
    assertThat(ts).hasReceivedLastValue("the last value");
    assertThat(ts).hasReceivedFirstValueWhich()
                  .is(notEmptyOrNull());
    assertThat(ts).hasReceivedLastValueWhich()
                  .is(notEmptyOrNull());

OnError Assertions

Received an IOException instance in onError:

    assertThat(ts).hasError(IOException.class);

Assert conditions for onError events (currently only as Throwable instances):

    assertThat(ts).hasErrorWhich()
                  .hasMessageStartingWith("A terrible error");

Concurrency Handling

Handle concurrency, by ensuring that the TestSubscriber awaits a terminal event before asserting:

    assertThat(ts).afterTerminalEvent()
                  .hasNoErrors()
                  .hasReceivedValue("someValue")
                  .hasCompleted();

Download

Releases are available as dependencies via Jitpack.

Implementation

The library is built as an extension to the AssertJ framework, but to avoid duplication of the assertion logic in TestSubscriber, in most cases it simply calls through to the TestSubscriber assertion methods. The exceptions to this are the higher level assertions, which are provided by returning instances of AssertJ assertions.

Acknowledgements

Brought to you by the power of the Chilicorn and the Futurice Open Source Program.

License

Copyright 2016 Peter Tackage

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.