am 174dc3ba: Merge "docs: Added training docs for Android unit testing tools...

    <dd>Learn how to test UI in a single app by using the Espresso testing framework.</dd>

  <dt><strong><a href="uiautomator-testing.html">

Testing UI for Multiple Apps</a></strong></dt>

    <dd>Learn how to test UI in multiple apps by using the UI Automator testing framework</dd>

    <dd>Learn how to test UI in multiple apps by using the UI Automator testing framework.</dd>

</dl>

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page.title=Building Effective Unit Tests

page.tags=testing,androidjunitrunner,junit,unit test

trainingnavtop=true

startpage=true

@jd:body

<div id="tb-wrapper">

<div id="tb">

        <h2>

          You should also read

        </h2>

        <ul>

          <li>

            <a href="{@docRoot}tools/testing-support-library/index.html">Testing Support Library</a>

          </li>

        </ul>

</div>

</div>

<p>Unit tests are the fundamental tests in your app testing strategy. By creating and running unit

tests against your code, you can easily verify that the logic of individual units is correct.

Running unit tests after every build helps you to

quickly catch and fix software regressions introduced by code changes to your app.

</p>

<p>A unit test generally exercises the functionality of the smallest possible unit of code (which

could be a method, class, or component) in a repeatable way. You should build unit tests when you

need to verify the logic of specific code in your app. For example, if you are unit testing a

class, your test might check that the class is in the right state. Typically, the unit of code

is tested in isolation; your test affects and monitors changes to that unit only. A

<a href="http://en.wikipedia.org/wiki/Mock_object" class="external-link">mocking framework</a>

can be used to isolate your unit from its dependencies.</p>

<p class="note"><strong>Note:</strong> Unit tests are not suitable for testing

complex UI interaction events. Instead, you should use the UI testing frameworks, as described in

<a href="{@docRoot}training/testing/ui-testing/index.html">Automating UI Tests</a>.</p>

<p>For testing Android apps, you typically create these types of automated unit tests:</p>

<ul>

<li><strong>Local tests:</strong> Unit tests that run on your local machine only. These tests are

compiled to run locally on the Java Virtual Machine (JVM) to minimize execution time. Use this

approach to run unit tests that have no dependencies on the Android framework or have dependencies

that can be filled by using mock objects.</li>

<li><strong>Instrumented tests:</strong> Unit tests that run on an Android device or emulator.

These tests have access to instrumentation information, such as the

{@link android.content.Context} for the app under test. Use this approach to run unit tests that

have Android dependencies which cannot be easily filled by using mock objects.</li>

</ul>

<p>The lessons in this class teach you how to build these types of automated unit tests.</p>

<h2>Lessons</h2>

<dl>

  <dt><strong><a href="local-unit-tests.html">

Building Local Unit Tests</a></strong></dt>

    <dd>Learn how to build unit tests that run on your local machine.</dd>

  <dt><strong><a href="instrumented-unit-tests.html">

Building Instrumented Unit Tests</a></strong></dt>

    <dd>Learn how to build unit tests that run on an Android device or emulator.</dd>

</dl>

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page.title=Building Instrumented Unit Tests

page.tags=testing,androidjunitrunner,junit,unit test,mock,instrumentation

trainingnavtop=true

@jd:body

<!-- This is the training bar -->

<div id="tb-wrapper">

<div id="tb">

  <h2>Dependencies and Prerequisites</h2>

  <ul>

    <li>Android 2.2 (API level 8) or higher</li>

    <li><a href="{@docRoot}tools/testing-support-library/index.html">

      Android Testing Support Library</a></li>

  </ul>

  <h2>This lesson teaches you to</h2>

  <ol>

    <li><a href="#setup">Set Up Your Testing Environment</a></li>

    <li><a href="#build">Create a Instrumented Unit Test Class</a></li>

    <li><a href="#run">Run Instrumented Unit Tests</a></li>

  </ol>

  <h2>Try it out</h2>

  <ul>

    <li>

<a href="https://github.com/googlesamples/android-testing/tree/master/unittesting/BasicUnitAndroidTest"

class="external-link">Instrumented Unit Tests Code Samples</a></li>

  </ul>

</div>

</div>

<p>

Instrumented unit tests are unit tests that run on physical devices and emulators, instead of

the Java Virtual Machine (JVM) on your local machine. You should create instrumented unit tests

if your tests need access to instrumentation information (such as the target app's

{@link android.content.Context}) or if they require the real implementation of an Android framework

component (such as a {@link android.os.Parcelable} or {@link android.content.SharedPreferences}

object). Using instrumented unit tests also helps to reduce the effort required to write and

maintain mock code. You are still free to use a mocking framework, if you choose, to simulate any

dependency relationships. Instrumented unit tests can take advantage of the Android framework APIs

and supporting APIs, such as the Android Testing Support Library.

</p>

<h2 id="setup">Set Up Your Testing Environment</h2>

<p>Before building instrumented unit tests, you must:</p>

  <ul>

      <li>

        <strong>Install the Android Testing Support Library</strong>. The

        <a href="{@docRoot}reference/android/support/test/runner/AndroidJUnitRunner.html">

        {@code AndroidJUnitRunner}</a> API, located under the

        {@code com.android.support.test.runner} package, allows you to

        create and run instrumented unit tests.  To learn how to install the

        library, see <a href="{@docRoot}tools/testing-support-library/index.html#setup">

        Testing Support Library Setup</a>.

      </li>

      <li>

        <strong>Set up your project structure.</strong> In your Gradle project, the source code for

        the target app that you want to test is typically placed under the {@code app/src/main/java}

        folder. The source code for instrumentatation tests, including your unit tests, must be

        placed under the <code>app/src/androidTest/java</code> folder.

        To learn more about setting up your project directory, see

        <a href="{@docRoot}tools/projects/index.html">Managing Projects</a>.

      </li>

      <li>

        <strong>Specify your Android testing dependencies</strong>. In order for the

        <a href="{@docRoot}tools/building/plugin-for-gradle.html">Android Plug-in for Gradle</a> to

        correctly build and run your instrumented unit tests, you must specify the following

        libraries in the {@code build.gradle} file of your Android app module:

        <pre>

dependencies {

    androidTestCompile 'com.android.support.test:runner:0.2'

    androidTestCompile 'com.android.support.test:rules:0.2'

    // Set this dependency if you want to use Hamcrest matching

    androidTestCompile 'org.hamcrest:hamcrest-library:1.1'

}

</pre>

      </li>

  </ul>

<h2 id="build">Create an Instrumented Unit Test Class</h2>

<p>

Your instrumented unit test class should be written as a JUnit 4 test class. To learn more about

creating JUnit 4 test classes and using JUnit 4 assertions and annotations, see

<a href="local-unit-tests.html#build">Create a Local Unit Test Class</a>.

</p>

<p>To create an instrumented JUnit 4 test class, add the {@code &#64;RunWith(AndroidJUnit4.class)}

annotation at the beginning of your test class definition. You also need to specify the

<a href="{@docRoot}reference/android/support/test/runner/AndroidJUnitRunner.html">

{@code AndroidJUnitRunner}</a> class

provided in the Android Testing Support Library as your default test runner. This step is described

in more detail in <a href="#run">Run Instrumented Unit Tests</a>.

</p>

<p>The following example shows how you might write an instrumented unit test to test that

the {@link android.os.Parcelable} interface is implemented correctly for the

{@code LogHistory} class:</p>

<pre>

import android.os.Parcel;

import android.support.test.runner.AndroidJUnit4;

import android.util.Pair;

import org.junit.Test;

import org.junit.runner.RunWith;

import java.util.List;

import static org.hamcrest.Matchers.is;

import static org.junit.Assert.assertThat;

@RunWith(AndroidJUnit4.class)

public class LogHistoryAndroidUnitTest {

    public static final String TEST_STRING = "This is a string";

    public static final long TEST_LONG = 12345678L;

    private LogHistory mLogHistory;

    @Before

    public void createLogHistory() {

        mLogHistory = new LogHistory();

    }

    @Test

    public void logHistory_ParcelableWriteRead() {

        // Set up the Parcelable object to send and receive.

        mLogHistory.addEntry(TEST_STRING, TEST_LONG);

        // Write the data.

        Parcel parcel = Parcel.obtain();

        mLogHistory.writeToParcel(parcel, mLogHistory.describeContents());

        // After you're done with writing, you need to reset the parcel for reading.

        parcel.setDataPosition(0);

        // Read the data.

        LogHistory createdFromParcel = LogHistory.CREATOR.createFromParcel(parcel);

        List<Pair<String, Long>> createdFromParcelData = createdFromParcel.getData();

        // Verify that the received data is correct.

        assertThat(createdFromParcelData.size(), is(1));

        assertThat(createdFromParcelData.get(0).first, is(TEST_STRING));

        assertThat(createdFromParcelData.get(0).second, is(TEST_LONG));

    }

}

</pre>

<h3 id="test-suites">Creating a test suite</h3>

<p>

To organize the execution of your instrumented unit tests, you can group a collection of test

classes in a <em>test suite</em> class and run these tests together. Test suites can be nested;

your test suite can group other test suites and run all their component test classes together.

</p>

<p>

A test suite is contained in a test package, similar to the main application package. By

convention, the test suite package name usually ends with the {@code .suite} suffix (for example,

{@code com.example.android.testing.mysample.suite}).

</p>

<p>

To create a test suite for your unit tests, import the JUnit

<a href="http://junit.sourceforge.net/javadoc/org/junit/runner/RunWith.html"

class="external-link">{@code RunWith}</a> and

<a href="http://junit.sourceforge.net/javadoc/org/junit/runners/Suite.html"

class="external-link">{@code Suite}</a> classes. In your test suite, add the

{@code @RunWith(Suite.class)} and the {@code @Suite.SuitClasses()} annotations. In

the {@code @Suite.SuiteClasses()} annotation, list the individual test classes or test

suites as arguments.

</p>

<p>

The following example shows how you might implement a test suite called {@code UnitTestSuite}

that groups and runs the {@code CalculatorInstrumentationTest} and

{@code CalculatorAddParameterizedTest} test classes together.

</p>

<pre>

import com.example.android.testing.mysample.CalculatorAddParameterizedTest;

import com.example.android.testing.mysample.CalculatorInstrumentationTest;

import org.junit.runner.RunWith;

import org.junit.runners.Suite;

// Runs all unit tests.

@RunWith(Suite.class)

@Suite.SuiteClasses({CalculatorInstrumentationTest.class,

        CalculatorAddParameterizedTest.class})

public class UnitTestSuite {}

</pre>

<h2 id="run">Run Instrumented Unit Tests</h2>

<p>

The

<a href="https://developer.android.com/tools/building/plugin-for-gradle.html">

  Android Plug-in for Gradle</a>

provides a default directory ({@code src/androidTest/java}) for you to store the instrumented unit

and integration test classes and test suites that you want to run on a device. The plug-in compiles

the test code in that directory and then executes the test app using a test runner class. You must

set the

<a href="{@docRoot}reference/android/support/test/runner/AndroidJUnitRunner.html">

{@code AndroidJUnitRunner}</a> class provided in the

<a href="{@docRoot}tools/testing-support-library/index.html">Android Testing Support Library</a>

as your default test runner.</p>

</p>

<p>To specify

<a href="{@docRoot}reference/android/support/test/runner/AndroidJUnitRunner.html">

{@code AndroidJUnitRunner}</a> as the default test instrumentation runner, add the following

setting in your {@code build.gradle} file:</p>

<pre>

android {

    defaultConfig {

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

    }

}

</pre>

<h3 id="run-from-Android-Studio">Running instrumented unit tests from Android Studio</h3>

<p>

To run instrumented unit tests in your Gradle project from Android Studio:

</p>

<ol>

<li>Open the <strong>Build Variants</strong> window by clicking the left-hand tab, then set the

test artifact to <em>Android Instrumentation Tests</em>.

</li>

<li>In the <strong>Project</strong> window, drill down to your unit test class or method, then

  right-click and run it using the Android Test configuration.

</li>

</ol>

<p>Android Studio displays the results of the unit test execution in the <strong>Run</strong>

window.</p>

<h3 id="run-from-commandline">Running instrumented unit tests from the command-line</h3>

<p>To run instrumented unit tests in your Gradle project from the command-line, call the

  {@code connectedCheck} (or {@code cC}) task:</p>

<pre>

./gradlew cC

</pre>

<p>You can find the generated HTML test result reports in the

{@code <path_to_your_project>/app/build/outputs/reports/androidTests/connected/} directory,

and the corresponding XML files in the

{@code &lt;path_to_your_project&gt;/app/build/outputs/androidTest-results/connected/} directory.</p>

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            <span class="en">Building Local Unit Tests</span>

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