Unit Testing in Android? [closed]

Question

I am using Android Studio 1.2

Say I have a simple method add in some class MyAdder

public int add(int a,int b) {
    return a+b;
}

I want to perform the unit test and use assertions to perform the test for the above-mentioned code.

I found it tough, to begin with, Testing Fundamentals from the official DEV site so a sample code or a detailed tutorial for performing unit tests would be appreciated.

Answer 1

Two types of tests are supported, available in a drop-down menu in the Build Variants tool window of Android Studio:

1. Android Instrumentation Tests: integration/functional testing using a running app on a device or on an emulator, often referred to as Android Tests
2. Unit Tests: plain JUnit tests that run on a local JVM, with a stubbed android.jar provided

The Testing Fundamentals page mostly discusses Android Instrumentation Tests, with which, as you noted, is a bit tough to get started.

For your question, however, you just need Unit Tests.

From the Unit testing support page:

1. Update build.gradle to use the android gradle plugin version 1.1.0-rc1 or later (either manually in build.gradle file or in the UI in File > Project Structure)
2. Add necessary testing dependencies to app/build.gradle

dependencies {
  testCompile "junit:junit:4.12"
}

3. Enable the unit testing feature in Settings > Gradle > Experimental. (enabled and no longer experimental as of Android Studio 1.2)
4. Sync your project.
5. Open the "Build variants" tool window (on the left) and change the test artifact to "Unit tests".
6. Create a directory for your testing source code, i.e. src/test/java. You can do this from the command line or using the Project view in the Project tool window. The new directory should be highlighted in green at this point. Note: names of the test source directories are determined by the gradle plugin based on a convention.

Here is some sample code to test the instance method in your question (replace com/domain/appname with the path created by your package name):

projectname/app/src/test/java/com/domain/appname/MyAdderTest.java

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class MyAdderTest {
    private MyAdder mMyAdder;

    @Before
    public void setUp() throws Exception {
        // Code that you wish to run before each test
        mMyAdder = new MyAdder();
    }

    @After
    public void tearDown() throws Exception {
        // Code that you wish to run after each test
    }

    @Test
    public void testAdd() {
        final int sum = mMyAdder.add(3, 5);
        assertEquals(8, sum);        
    }
}