AssertJ Android

A set of AssertJ assertions geared toward testing Android.

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Writing tests is not the most glamorous part of developing an Android application but it is an invaluable one. Using libraries like JUnit and AssertJ provide a great starting point for writing tests.

This library is an extension of AssertJ which aims to make it even easier to test Android.

AssertJ Android

assertThat(view).isGone();

Regular JUnit

assertEquals(View.GONE, view.getVisibility());

Regular AssertJ

assertThat(view.getVisibility()).isEqualTo(View.GONE);

When failing, the AssertJ Android assertion produces an output which allows you to immediately recognize the problem: Expected visibility <gone> but was <invisible>.

Compare that to the output of regular AssertJ expected:<[8]> but was:<[4]> and regular JUnit expected: <8> but was: <4> and you should immediately see the advantage.

Because AssertJ Android offers assertions directly on objects rather than properties they can be chained together.

AssertJ Android

assertThat(layout).isVisible()
    .isVertical()
    .hasChildCount(4)
    .hasShowDividers(SHOW_DIVIDERS_MIDDLE);

Regular JUnit

assertEquals(View.VISIBLE, layout.getVisibility());
assertEquals(VERTICAL, layout.getOrientation());
assertEquals(4, layout.getChildCount());
assertEquals(SHOW_DIVIDERS_MIDDLE, layout.getShowDividers());

Regular AssertJ

assertThat(layout.getVisibility()).isEqualTo(View.VISIBLE);
assertThat(layout.getOrientation()).isEqualTo(VERTICAL);
assertThat(layout.getChildCount()).isEqualTo(4);
assertThat(layout.getShowDividers()).isEqualTo(SHOW_DIVIDERS_MIDDLE);

Assertions exist for nearly every object that you would ever want to test, from LinearLayout to ActionBar to Fragment to MenuItem. Everything in the support library is included too.

To get started writing tests add the following import:

import static org.assertj.android.api.Assertions.assertThat;

Add-On Modules

Modules are also provided for the add-on Android libraries. Add the dependency (listed below) and use the following imports:

support-v4

import static org.assertj.android.support.v4.api.Assertions.assertThat;

Google Play Services

import static org.assertj.android.playservices.api.Assertions.assertThat;

appcompat-v7

import static org.assertj.android.appcompat.v7.api.Assertions.assertThat;

mediarouter-v7

import static org.assertj.android.mediarouter.v7.api.Assertions.assertThat;

gridlayout-v7

import static org.assertj.android.gridlayout.v7.api.Assertions.assertThat;

cardview-v7

import static org.assertj.android.cardview.v7.api.Assertions.assertThat;

recyclerview-v7

import static org.assertj.android.recyclerview.v4.api.Assertions.assertThat;

pallete-v7

import static org.assertj.android.pallete.v4.api.Assertions.assertThat;

Extending

The provided assertions have also been designed to be extended for any custom controls you have developed.

public class CustomLayout extends LinearLayout {
  public int getBehavior() {
    /* ... */
  }
}

Use the following pattern to set up your assertions.

public class CustomLayoutAssert extends AbstractLinearLayoutAssert<CustomLayoutAssert, CustomLayout> {
  public static CustomLayoutAssert assertThat(CustomLayout actual) {
    return new CustomLayoutAssert(actual);
  }

  public CustomLayoutAssert(CustomLayout actual) {
    super(actual, CustomLayoutAssert.class);
  }

  public CustomLayoutAssert hasSomeBehavior() {
    isNotNull();
    assertThat(actual.getBehavior())
        .overridingErrorMessage("Expected some behavior but was doing other behavior.")
        .isEqualTo(42)
    return this;
  }
}

Now static import CustomLayoutAssert.assertThat in your test classes.

For more information about writing custom assertions see the official documentation.

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Android module:

androidTestCompile 'com.squareup.assertj:assertj-android:1.0.0'

support-v4 module:

androidTestCompile 'com.squareup.assertj:assertj-android-support-v4:1.0.0'

Google Play Services module:

androidTestCompile 'com.squareup.assertj:assertj-android-play-services:1.0.0'

appcompat-v7 module:

androidTestCompile 'com.squareup.assertj:assertj-android-appcompat-v7:1.0.0'

mediarouter-v7 module:

androidTestCompile 'com.squareup.assertj:assertj-android-mediarouter-v7:1.0.0'

gridlayout-v7 module:

androidTestCompile 'com.squareup.assertj:assertj-android-gridlayout-v7:1.0.0'

cardview-v7 module:

androidTestCompile 'com.squareup.assertj:assertj-android-cardview-v7:1.0.0'

recyclerview-v7 module:

androidTestCompile 'com.squareup.assertj:assertj-android-recyclerview-v7:1.0.0'

pallete-v7 module:

androidTestCompile 'com.squareup.assertj:assertj-android-pallete-v7:1.0.0'