Getting context in AndroidTestCase or InstrumentationTestCase in Android Studio's Unit Test feature

Updated - Please use Espresso for writing instrumentation tests

Newer Examples:

I got these working without deploying to a device. Put the tests in the /src/main/test/ folder.

Here are newer examples, I took your examples and tested them in my own temporary test project. I ran the tests via command line: ./gradlew clean test. Please read more here: https://sites.google.com/a/android.com/tools/tech-docs/unit-testing-support.

Top build.gradle:

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.1.3'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

App build.gradle:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 22
    buildToolsVersion "22.0.0"

    defaultConfig {
        applicationId "com.test"
        minSdkVersion 9
        targetSdkVersion 22
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    testOptions { // <-- You need this
        unitTests {
            returnDefaultValues = true
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.0.0'

    testCompile 'junit:junit:4.12' // <-- You need this
}

Basic Tests:

InstrumentationTestCaseTest to test Context and Assertions.

import android.content.Context;
import android.test.InstrumentationTestCase;
import android.test.mock.MockContext;

public class InstrumentationTestCaseTest extends InstrumentationTestCase {

    Context context;

    public void setUp() throws Exception {
        super.setUp();

        context = new MockContext();

        assertNotNull(context);

    }

    public void testSomething() {

        assertEquals(false, true);
    }

}

ActivityTestCase to test your Resources.

import android.content.Context;
import android.content.res.Resources;
import android.test.ActivityTestCase;

public class ActivityTestCaseTest extends ActivityTestCase {

    public void testFoo() {

        Context testContext = getInstrumentation().getContext();
        Resources testRes = testContext.getResources();

        assertNotNull(testRes);
        assertNotNull(testRes.getString(R.string.app_name));
    }
}

AndroidTestCase to test Context and Assertions.

import android.content.Context;
import android.test.AndroidTestCase;
import android.test.mock.MockContext;

public class AndroidTestCaseTest extends AndroidTestCase {

    Context context;

    public void setUp() throws Exception {
        super.setUp();

        context = new MockContext();

        setContext(context);

        assertNotNull(context);

    }

    // Fake failed test
    public void testSomething()  {
        assertEquals(false, true);
    }
}

Googling Old Examples:

After Googling a lot bout this error, I believe your bet is to use getInstrumentation().getContext().getResources().openRawResource(R.raw.your_res). or something similar in order to test your resources.

Using InstrumentationTestCase:

Test Resources:

public class PrintoutPullParserTest extends InstrumentationTestCase {

    public void testParsing() throws Exception {
        PrintoutPullParser parser = new PrintoutPullParser();
        parser.parse(getInstrumentation().getContext().getResources().getXml(R.xml.printer_configuration));
    }
}

Source: https://stackoverflow.com/a/8870318/950427 and https://stackoverflow.com/a/16763196/950427

Using ActivityTestCase:

Test Resources:

public class Test extends ActivityTestCase {

   public void testFoo() {  

      // .. test project environment
      Context testContext = getInstrumentation().getContext();
      Resources testRes = testContext.getResources();
      InputStream ts = testRes.openRawResource(R.raw.your_res);

      assertNotNull(testRes);
   }    
}

Source: https://stackoverflow.com/a/9820390/950427

Using AndroidTestCase:

Getting the Context (a simple hack):

private Context getTestContext() {
    try {
        Method getTestContext = ServiceTestCase.class.getMethod("getTestContext");
        return (Context) getTestContext.invoke(this);
    } catch (final Exception exception) {
        exception.printStackTrace();
        return null;
    }
}

Source: https://stackoverflow.com/a/14232913/950427

But, if you look a the source code of AndroidTestCase, it looks like you need to set a Context yourself:

Source: http://alvinalexander.com/java/jwarehouse/android/core/java/android/test/AndroidTestCase.java.shtml

With the Android Testing Support Library, you can

• get test apk context with InstrumentationRegistry.getContext()
• get app apk context with InstrumentationRegistry.getTargetContext()
• get Instrumentation with InstrumentationRegistry.getInstrumentation()

See the bottom of the linked page for how to add Testing Support library to your project.

Here is a recent way to setup (unit) instrumentation tests

Setup

In your build.gradle add:

testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

and the following dependencies:

// Instrumentation tests
androidTestImplementation "com.android.support.test:runner:$supportTestRunnerVersion"
// To use assertThat syntax
androidTestImplementation "org.assertj:assertj-core:$assertJVersion"

Example class

public class Example {

    public Object doSomething() {
        // Context is used here
    }

}

Example test

import android.content.Context;
import android.support.test.InstrumentationRegistry;
import android.support.test.runner.AndroidJUnit4;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;

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

@RunWith(AndroidJUnit4.class)
public class ExampleTest {

    private Context context;

    @Before
    public void setUp() {
        // In case you need the context in your test
        context = InstrumentationRegistry.getTargetContext();
    }

    @Test
    public void doSomething() {
        Example example = new Example();
        assertThat(example.doSomething()).isNotNull();
    }

}

Documentation

• Building Instrumented Unit Tests | Android Developers