https://github.com/jraska/livedata-testing

TestObserver to easily test LiveData and make assertions on them.
https://github.com/jraska/livedata-testing

android architecture-components livedata testing viewmodel-pattern

Last synced: 3 months ago
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TestObserver to easily test LiveData and make assertions on them.

• Host: GitHub
• URL: https://github.com/jraska/livedata-testing
• Owner: jraska
• License: apache-2.0
• Created: 2018-07-18T22:12:53.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2024-11-04T21:31:47.000Z (3 months ago)
• Last Synced: 2024-11-04T22:27:29.185Z (3 months ago)
• Topics: android, architecture-components, livedata, testing, viewmodel-pattern
• Language: Java
• Size: 385 KB
• Stars: 398
• Watchers: 8
• Forks: 21
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# LiveData Testing

TestObserver to easily test LiveData and make assertions on them.

[![Maven Central](https://img.shields.io/maven-central/v/com.jraska.livedata/testing-ktx.svg?label=Maven%20Central)](https://search.maven.org/search?q=g:%22com.jraska.livedata%22%20AND%20a:%22testing-ktx%22)

[![License](https://img.shields.io/badge/license-Apache%202.0-green.svg) ](https://github.com/jraska/livedata-testing/blob/master/LICENSE)

[![Android Arsenal]( https://img.shields.io/badge/Android%20Arsenal-LiveData%20Testing-green.svg?style=flat )]( https://android-arsenal.com/details/1/7255 )

Read [Medium Article](https://medium.com/@josef.raska/effective-livedata-and-viewmodel-testing-17f25069fcd4) for more info.

[![Explanatory Diagram](img/livedata-testing.png)](https://medium.com/@josef.raska/effective-livedata-and-viewmodel-testing-17f25069fcd4)

## Usage

Having `LiveData` of counter from 0 to 4:

Kotlin - see [ExampleTest.kt](https://github.com/jraska/livedata-testing/blob/master/testing-ktx/src/test/java/com/jraska/livedata/example/ExampleTest.kt)

```java

liveData.test()

  .awaitValue()

  .assertHasValue()

  .assertValue { it > 3 }

  .assertValue(4)

  .assertHistorySize(5)

  .assertNever { it > 4 }

// Assertion on structures with a lot of nesting

viewLiveData.map { it.items[0].header.title }

  .assertValue("Expected title")

```

Java - see [ExampleTest.java](https://github.com/jraska/livedata-testing/blob/master/testing-ktx/src/test/java/com/jraska/livedata/example/ExampleJavaTest.java)

```java

TestObserver.test(liveData)

  .awaitValue()

  .assertHasValue()

  .assertValue(value -> value > 3)

  .assertValue(4)

  .assertHistorySize(5)

  .assertNever(value -> value > 4);

```

Don't forget to use `InstantTaskExecutorRule` from `androidx.arch.core:core-testing` to make your LiveData test run properly.

## Download

##### Kotlin users:

```groovy

testImplementation 'com.jraska.livedata:testing-ktx:1.3.0'

```

##### Java users:

```groovy

testImplementation 'com.jraska.livedata:testing:1.3.0'

```

## [Philosophy](https://medium.com/@josef.raska/effective-livedata-and-viewmodel-testing-17f25069fcd4)

This library is created in a belief that to effective and valuable test should be fast to write and model real code usage.

As by Architecture components spec Activity should communicate with its ViewModel only through observing LiveData.

TestObserver in this case simulates the Activity and by testing LiveData, we could test our whole logic except the View where the responsibility belongs to Activity.

Key ideas:

* Test pretends to be an Activity

* No Android framework mocking or Robolectric - just standard fast JUnit tests

* Fluent API inspired by RxJava TestObserver

* Easy to write fast executing tests - possibly TDD