Robolectric Installation for Unit Testing

Robolectric Android Studio Setup

Robolectric is a framework that allows Android applications to be tested on the JVM using JUnit 4 (no emulator or device needed!). More info about robolectric is available here.

In this guide, we'll walk through the steps necessary to add Robolectric to an existing project.

Prerequisites:

• Android Studio 1.2.1.1+
• Android Gradle Plugin 1.2.3+
• Gradle 2.2.1+

Note: Robolectric can also be configured with Android Studio 1.1, but the setup requires the robolectric gradle plugin and some additional configuration. Also, keep in mind that unit testing was still considered an experimental feature in Android Studio 1.1.

App build.gradle

First, we need to add the following to the app build.gradle. Robolectric's latest version is currently 3.0.

dependencies {
  ...
  testCompile 'org.robolectric:robolectric:3.0'
}

Android Studio Configuration

Next, there are a couple things we need to configure in Android Studio for running unit tests. One very important setting is the Test Artifact setting that toggles between Unit Tests and Android Instrumentation Tests. This setting controls the visibility of the corresponding tests in the project browser.

For each type of test, Android Studio defaults to looking for tests in the following locations:

• Unit Tests => src/test/java
• Android Instrumentation Tests => src/androidTest/java

Since we will be creating unit tests, we need our robolectric tests to live in src/test/java. The easiest way to create this folder (if instrumentations tests aren't also needed) is to rename the androidTest folder to test like so:

Note: If you are using a Mac, there is a known issue that needs to be addressed so that tests can be located properly. Go to Run -> Edit Configurations -> Defaults -> Junit and make sure to set $MODULE_DIR$ as the working directory. You can see the Robolectric getting started guide for more information.

That's all the setup needed. Now we can move on to writing a test.

Creating a Robolectric test

The code below shows a basic Robolectric test that verifies the expected text inside of a TextView. To enable this test:

1. Make sure you have a test file named MainActivityTest.java (you can rename ApplicationTest.java to MainActivityTest.java if you'd like)
2. Make sure your app has an Activity named MainActivity
3. Add a TextView to MainActivity named tvHello containing the text "Hello world!"
4. Copy the code below into MainActivityTest.java

import android.widget.TextView;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.robolectric.Robolectric;
import org.robolectric.RobolectricGradleTestRunner;
import org.robolectric.annotation.Config;

import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;

@Config(constants = BuildConfig.class, sdk = 21)
@RunWith(RobolectricGradleTestRunner.class)
public class MainActivityTest {
    private MainActivity activity;

    @Before
    public void setup() throws Exception {
        activity = Robolectric.setupActivity(MainActivity.class);
        assertNotNull("MainActivity is not instantiated", activity);
    }

    @Test
    public void validateTextViewContent() throws Exception {
        TextView tvHelloWorld = (TextView) activity.findViewById(R.id.tvHello);
        assertNotNull("TextView could not be found", tvHelloWorld);
        assertTrue("TextView contains incorrect text",
                "Hello world!".equals(tvHelloWorld.getText().toString()));
    }
}

Note: Robolectric currently doesn't support API level 22 (Android 5.1). If your app targets API 22, you will need to specify the sdk = 21 annotation.

Running tests

1. Android Studio - Make sure you run the test as a Gradle test (the first item). The first item is for a Gradle test, while the 2nd item is for JUnit.

If all goes well, you will see the passing results in the console. Note: you may need to enable Show Passed as in the diagram to see the full results.

To run tests on the command line ./gradlew test

References

• http://robolectric.org/
• https://github.com/robolectric/robolectric/
• https://www.bignerdranch.com/blog/triumph-android-studio-1-2-sneaks-in-full-testing-support/
• https://github.com/mutexkid/android-studio-robolectric-example