page.title=Testing UI for a Single App
page.tags=testing,espresso
trainingnavtop=true
@jd:body
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<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 Espresso</a>
</li>
<li>
<a href="#build">Create an Espresso Test Class</a>
</li>
<li>
<a href="#run">Run Espresso Tests on a Device or Emulator</a>
</li>
</ol>
<h2>
You should also read
</h2>
<ul>
<li><a href="{@docRoot}reference/android/support/test/package-summary.html">
Espresso API Reference</a></li>
</ul>
<h2>
Try it out
</h2>
<ul>
<li>
<a href="https://github.com/googlesamples/android-testing"
class="external-link">Espresso Code Samples</a>
</li>
</ul>
</div>
</div>
<p>
Testing user interactions
within a single app helps to ensure that users do not
encounter unexpected results or have a poor experience when interacting with your app.
You should get into the habit of creating user interface (UI) tests if you need to verify
that the UI of your app is functioning correctly.
</p>
<p>
The Espresso testing framework, provided by the
<a href="{@docRoot}tools/testing-support-library/index.html">Android Testing Support Library</a>,
provides APIs for writing UI tests to simulate user interactions within a
single target app. Espresso tests can run on devices running Android 2.2 (API level 8) and
higher. A key benefit of using Espresso is that it provides automatic synchronization of test
actions with the UI of the app you are testing. Espresso detects when the main thread is idle,
so it is able to run your test commands at the appropriate time, improving the reliability of
your tests. This capability also relieves you from having to adding any timing workarounds,
such as a sleep period, in your test code.
</p>
<p>
The Espresso testing framework is an instrumentation-based API and works
with the
<a href="{@docRoot}reference/android/support/test/runner/AndroidJUnitRunner.html">{@code
AndroidJUnitRunner}</a> test runner.
</p>
<h2 id="setup">
Set Up Espresso
</h2>
<p>
Before you begin using Espresso, you must:
</p>
<ul>
<li>
<strong>Install the Android Testing Support Library</strong>. The Espresso API is
located under the {@code com.android.support.test.espresso} package. These classes allow
you to create tests that use the Espresso testing framework. 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}
folder. The source code for instrumentation tests, including
your Espresso tests, must be placed under the <code>app/src/androidTest</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 Espresso 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:0.3'
androidTestCompile 'com.android.support.test:rules:0.3'
androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2'
}
</pre>
</li>
<li>
<strong>Turn off animations on your test device.</strong> Leaving system animations turned
on in the test device might cause unexpected results or may lead your test to fail. Turn
off animations from <em>Settings</em> by opening <em>Developing Options</em> and
turning all the following options off:
<ul>
<li>
<em>Window animation scale</em>
</li>
<li>
<em>Transition animation scale</em>
</li>
<li>
<em>Animator duration scale</em>
</li>
</ul>
</li>
</ul>
<h2 id="build">
Create an Espresso Test Class
</h2>
<p>
To create an Espresso test, create a Java class or an
{@link android.test.ActivityInstrumentationTestCase2}
subclass that follows this programming model:
</p>
<ol>
<li>Find the UI component you want to test in an {@link android.app.Activity} (for example, a
sign-in button in the app) by calling the
<a href="{@docRoot}reference/android/support/test/espresso/Espresso.html#onView(org.hamcrest.Matcher<android.view.View>)">
{@code onView()}</a> method, or the
<a href="{@docRoot}reference/android/support/test/espresso/Espresso.html#onData(org.hamcrest.Matcher<java.lang.Object>)">
{@code onData()}</a> method for {@link android.widget.AdapterView} controls.
</li>
<li>Simulate a specific user interaction to perform on that UI component, by calling the
<a href="{@docRoot}reference/android/support/test/espresso/ViewInteraction.html#perform(android.support.test.espresso.ViewAction...)">{@code ViewInteraction.perform()}</a>
or
<a href="{@docRoot}reference/android/support/test/espresso/DataInteraction.html#perform(android.support.test.espresso.ViewAction...)">{@code DataInteraction.perform()}</a>
method and passing in the user action (for example, click on the sign-in button). To sequence
multiple actions on the same UI component, chain them using a comma-separated list in your
method argument.
</li>
<li>Repeat the steps above as necessary, to simulate a user flow across multiple
activities in the target app.
</li>
<li>Use the
<a href="{@docRoot}reference/android/support/test/espresso/assertion/ViewAssertions.html">{@code ViewAssertions}</a>
methods to check that the UI reflects the expected
state or behavior, after these user interactions are performed.
</li>
</ol>
<p>
These steps are covered in more detail in the sections below.
</p>
<p>
The following code snippet shows how your test class might invoke this basic workflow:
</p>
<pre>
onView(withId(R.id.my_view)) // withId(R.id.my_view) is a ViewMatcher
.perform(click()) // click() is a ViewAction
.check(matches(isDisplayed())); // matches(isDisplayed()) is a ViewAssertion
</pre>
<h3 id="espresso-aitc2">
Using Espresso with ActivityInstrumentationTestCase2
</h3>
<p>
If you are subclassing {@link android.test.ActivityInstrumentationTestCase2}
to create your Espresso test class, you must inject an
{@link android.app.Instrumentation} instance into your test class. This step is required in
order for your Espresso test to run with the
<a href="{@docRoot}reference/android/support/test/runner/AndroidJUnitRunner.html">{@code AndroidJUnitRunner}</a>
test runner.
</p>
<p>
To do this, call the
{@link android.test.InstrumentationTestCase#injectInstrumentation(android.app.Instrumentation) injectInstrumentation()}
method and pass in the result of
<a href="{@docRoot}reference/android/support/test/InstrumentationRegistry.html#getInstrumentation()">
{@code InstrumentationRegistry.getInstrumentation()}</a>, as shown in the following code
example:
</p>
<pre>
import android.support.test.InstrumentationRegistry;
public class MyEspressoTest
extends ActivityInstrumentationTestCase2<MyActivity> {
private MyActivity mActivity;
public MyEspressoTest() {
super(MyActivity.class);
}
@Before
public void setUp() throws Exception {
super.setUp();
injectInstrumentation(InstrumentationRegistry.getInstrumentation());
mActivity = getActivity();
}
...
}
</pre>
<p class="note"><strong>Note:</strong> Previously, {@link android.test.InstrumentationTestRunner}
would inject the {@link android.app.Instrumentation} instance, but this test runner is being
deprecated.</p>
<h3 id="accessing-ui-components">
Accessing UI Components
</h3>
<p>
Before Espresso can interact with the app under test, you must first specify the UI component
or <em>view</em>. Espresso supports the use of
<a href="http://hamcrest.org/" class="external-link">Hamcrest matchers</a>
for specifying views and adapters in your app.
</p>
<p>
To find the view, call the <a href="{@docRoot}reference/android/support/test/espresso/Espresso.html#onView(org.hamcrest.Matcher<android.view.View>)">
{@code onView()}</a>
method and pass in a view matcher that specifies the view that you are targeting. This is
described in more detail in <a href="#specifying-view-matcher">Specifying a View Matcher</a>.
The <a href="{@docRoot}reference/android/support/test/espresso/Espresso.html#onView(org.hamcrest.Matcher<android.view.View>)">
{@code onView()}</a> method returns a
<a href="{@docRoot}reference/android/support/test/espresso/ViewInteraction.html">
{@code ViewInteraction}</a>
object that allows your test to interact with the view.
However, calling the <a href="{@docRoot}reference/android/support/test/espresso/Espresso.html#onView(org.hamcrest.Matcher<android.view.View>)">
{@code onView()}</a> method may not work if you want to locate a view in
an {@link android.widget.AdapterView} layout. In this case, follow the instructions in
<a href="#locating-adpeterview-view">Locating a view in an AdapterView</a> instead.
</p>
<p class="note">
<strong>Note</strong>: The <a href="{@docRoot}reference/android/support/test/espresso/Espresso.html#onView(org.hamcrest.Matcher<android.view.View>)">
{@code onView()}</a> method does not check if the view you specified is
valid. Instead, Espresso searches only the current view hierarchy, using the matcher provided.
If no match is found, the method throws a
<a href="{@docRoot}reference/android/support/test/espresso/NoMatchingViewException.html">
{@code NoMatchingViewException}</a>.
</p>
<p>
The following code snippet shows how you might write a test that accesses an
{@link android.widget.EditText} field, enters a string of text, closes the virtual keyboard,
and then performs a button click.
</p>
<pre>
public void testChangeText_sameActivity() {
// Type text and then press the button.
onView(withId(R.id.editTextUserInput))
.perform(typeText(STRING_TO_BE_TYPED), closeSoftKeyboard());
onView(withId(R.id.changeTextButton)).perform(click());
// Check that the text was changed.
...
}
</pre>
<h4 id="specifying-view-matcher">
Specifying a View Matcher
</h4>
<p>
You can specify a view matcher by using these approaches:
</p>
<ul>
<li>Calling methods in the
<a href="{@docRoot}reference/android/support/test/espresso/matcher/ViewMatchers.html">
{@code ViewMatchers}</a> class. For example, to find a view by looking for a text string it
displays, you can call a method like this:
<pre>
onView(withText("Sign-in"));
</pre>
<p>Similarly you can call
<a href="{@docRoot}reference/android/support/test/espresso/matcher/ViewMatchers.html#withId(int)">
{@code withId()}</a> and providing the resource ID ({@code R.id}) of the view, as shown in the
following example:</p>
<pre>
onView(withId(R.id.button_signin));
</pre>
<p>
Android resource IDs are not guaranteed to be unique. If your test attempts to match to a
resource ID used by more than one view, Espresso throws an
<a href="{@docRoot}reference/android/support/test/espresso/AmbiguousViewMatcherException.html">
{@code AmbiguousViewMatcherException}</a>.
</p>
</li>
<li>Using the Hamcrest
<a href="http://hamcrest.org/JavaHamcrest/javadoc/1.3/org/hamcrest/Matchers.html"
class="external-link">{@code Matchers}</a> class. You can use the
{@code allOf()} methods to combine multiple matchers, such as
{@code containsString()} and {@code instanceOf()}. This approach allows you to
filter the match results more narrowly, as shown in the following example:
<pre>
onView(allOf(withId(R.id.button_signin), withText("Sign-in")));
</pre>
<p>You can use the {@code not} keyword to filter for views that don't correspond to the matcher, as
shown in the following example:</p>
<pre>
onView(allOf(withId(R.id.button_signin), not(withText("Sign-out"))));
</pre>
<p>To use these methods in your test, import the {@code org.hamcrest.Matchers} package. To
learn more about Hamcrest matching, see the
<a href="http://hamcrest.org/" class="external-link">Hamcrest site</a>.
</p>
</li>
</ul>
<p>
To improve the performance of your Espresso tests, specify the minimum matching information
needed to find your target view. For example, if a view is uniquely identifiable by its
descriptive text, you do not need to specify that it is also assignable from the
{@link android.widget.TextView} instance.
</p>
<h4 id="#locating-adpeterview-view">
Locating a view in an AdapterView
</h4>
<p>
In an {@link android.widget.AdapterView} widget, the view is dynamically populated with child
views at runtime. If the target view you want to test is inside an
{@link android.widget.AdapterView}
(such as a {@link android.widget.ListView}, {@link android.widget.GridView}, or
{@link android.widget.Spinner}), the
<a href="{@docRoot}reference/android/support/test/espresso/Espresso.html#onView(org.hamcrest.Matcher<android.view.View>)">
{@code onView()}</a> method might not work because only a
subset of the views may be loaded in the current view hierarchy.
</p>
<p>
Instead, call the <a href="{@docRoot}reference/android/support/test/espresso/Espresso.html#onData(org.hamcrest.Matcher<java.lang.Object>)">{@code onData()}</a>
method to obtain a
<a href="{@docRoot}reference/android/support/test/espresso/DataInteraction.html">
{@code DataInteraction}</a>
object to access the target view element. Espresso handles loading the target view element
into the current view hierarchy. Espresso also takes care of scrolling to the target element,
and putting the element into focus.
</p>
<p class="note">
<strong>Note</strong>: The
<a href="{@docRoot}reference/android/support/test/espresso/Espresso.html#onData(org.hamcrest.Matcher<java.lang.Object>)">{@code onData()}</a>
method does not check if if the item you specified corresponds with a view. Espresso searches
only the current view hierarchy. If no match is found, the method throws a
<a href="{@docRoot}reference/android/support/test/espresso/NoMatchingViewException.html">
{@code NoMatchingViewException}</a>.
</p>
<p>
The following code snippet shows how you can use the
<a href="{@docRoot}reference/android/support/test/espresso/Espresso.html#onData(org.hamcrest.Matcher<java.lang.Object>)">{@code onData()}</a>
method together
with Hamcrest matching to search for a specific row in a list that contains a given string.
In this example, the {@code LongListActivity} class contains a list of strings exposed
through a {@link android.widget.SimpleAdapter}.
</p>
<pre>
onData(allOf(is(instanceOf(Map.class)),
hasEntry(equalTo(LongListActivity.ROW_TEXT), is(str))));
</pre>
<h3 id="perform-actions">
Performing Actions
</h3>
<p>
Call the <a href="{@docRoot}reference/android/support/test/espresso/ViewInteraction.html#perform(android.support.test.espresso.ViewAction...)">{@code ViewInteraction.perform()}</a>
or
<a href="{@docRoot}reference/android/support/test/espresso/DataInteraction.html#perform(android.support.test.espresso.ViewAction...)">{@code DataInteraction.perform()}</a>
methods to
simulate user interactions on the UI component. You must pass in one or more
<a href="{@docRoot}reference/android/support/test/espresso/ViewAction.html">{@code ViewAction}</a>
objects as arguments. Espresso fires each action in sequence according to
the given order, and executes them in the main thread.
</p>
<p>
The
<a href="{@docRoot}reference/android/support/test/espresso/action/ViewActions.html">{@code ViewActions}</a>
class provides a list of helper methods for specifying common actions.
You can use these methods as convenient shortcuts instead of creating and configuring
individual <a href="{@docRoot}reference/android/support/test/espresso/ViewAction.html">{@code ViewAction}</a>
objects. You can specify such actions as:
</p>
<ul>
<li>
<a href="{@docRoot}reference/android/support/test/espresso/action/ViewActions.html#click()">{@code ViewActions.click()}</a>:
Clicks on the view.
</li>
<li>
<a href="{@docRoot}reference/android/support/test/espresso/action/ViewActions.html#typeText(java.lang.String)">{@code ViewActions.typeText()}</a>:
Clicks on a view and enters a specified string.
</li>
<li>
<a href="{@docRoot}reference/android/support/test/espresso/action/ViewActions.html#scrollTo()">{@code ViewActions.scrollTo()}</a>:
Scrolls to the view. The
target view must be subclassed from {@link android.widget.ScrollView}
and the value of its
<a href="http://developer.android.com/reference/android/view/View.html#attr_android:visibility">{@code android:visibility}</a>
property must be {@link android.view.View#VISIBLE}. For views that extend
{@link android.widget.AdapterView} (for example,
{@link android.widget.ListView}),
the
<a href="{@docRoot}reference/android/support/test/espresso/Espresso.html#onData(org.hamcrest.Matcher<java.lang.Object>)">{@code onData()}</a>
method takes care of scrolling for you.
</li>
<li>
<a href="{@docRoot}reference/android/support/test/espresso/action/ViewActions.html#pressKey(int)">{@code ViewActions.pressKey()}</a>:
Performs a key press using a specified keycode.
</li>
<li>
<a href="{@docRoot}reference/android/support/test/espresso/action/ViewActions.html#clearText()">{@code ViewActions.clearText()}</a>:
Clears the text in the target view.
</li>
</ul>
<p>
If the target view is inside a {@link android.widget.ScrollView}, perform the
<a href="{@docRoot}reference/android/support/test/espresso/action/ViewActions.html#scrollTo()">{@code ViewActions.scrollTo()}</a>
action first to display the view in the screen before other proceeding
with other actions. The
<a href="{@docRoot}reference/android/support/test/espresso/action/ViewActions.html#scrollTo()">{@code ViewActions.scrollTo()}</a>
action will have no effect if the view is already displayed.
</p>
<h3 id="verify-results">
Verifying Results
</h3>
<p>
Call the
<a href="{@docRoot}reference/android/support/test/espresso/ViewInteraction.html#check(android.support.test.espresso.ViewAssertion)">{@code ViewInteraction.check()}</a>
or
<a href="{@docRoot}reference/android/support/test/espresso/DataInteraction.html#check(android.support.test.espresso.ViewAssertion)">{@code DataInteraction.check()}</a>
method to assert
that the view in the UI matches some expected state. You must pass in a
<a href="{@docRoot}reference/android/support/test/espresso/ViewAssertion.html">
{@code ViewAssertion}</a> object as the argument. If the assertion fails, Espresso throws
an {@link junit.framework.AssertionFailedError}.
</p>
<p>
The
<a href="{@docRoot}reference/android/support/test/espresso/assertion/ViewAssertions.html">{@code ViewAssertions}</a>
class provides a list of helper methods for specifying common
assertions. The assertions you can use include:
</p>
<ul>
<li>
<a href="{@docRoot}reference/android/support/test/espresso/assertion/ViewAssertions.html#doesNotExist()">{@code doesNotExist}</a>:
Asserts that there is no view matching the specified criteria in the current view hierarchy.
</li>
<li>
<a href="{@docRoot}reference/android/support/test/espresso/assertion/ViewAssertions.html#matches(org.hamcrest.Matcher<? super android.view.View>)">{@code matches}</a>:
Asserts that the specified view exists in the current view hierarchy
and its state matches some given Hamcrest matcher.
</li>
<li>
<a href="{@docRoot}reference/android/support/test/espresso/assertion/ViewAssertions.html#selectedDescendantsMatch(org.hamcrest.Matcher<android.view.View>, org.hamcrest.Matcher<android.view.View>)">{@code selectedDescendentsMatch}</a>
: Asserts that the specified children views for a
parent view exist, and their state matches some given Hamcrest matcher.
</li>
</ul>
<p>
The following code snippet shows how you might check that the text displayed in the UI has
the same value as the text previously entered in the
{@link android.widget.EditText} field.
</p>
<pre>
public void testChangeText_sameActivity() {
// Type text and then press the button.
...
// Check that the text was changed.
onView(withId(R.id.textToBeChanged))
.check(matches(withText(STRING_TO_BE_TYPED)));
}
</pre>
<h2 id="run">Run Espresso Tests on a Device or Emulator</h2>
<p>
To run Espresso tests, you must use 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. The
<a href="{@docRoot}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 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
the configured test runner class.
</p>
<p>
To run Espresso tests in your Gradle project:
</p>
<ol>
<li>Specify
<a href="{@docRoot}reference/android/support/test/runner/AndroidJUnitRunner.html">{@code AndroidJUnitRunner}</a>
as the default test instrumentation runner in
your {@code build.gradle} file:
<pre>
android {
defaultConfig {
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
}</pre>
</li>
<li>Run your tests from the command-line by calling the the {@code connectedCheck}
(or {@code cC}) task:
<pre>
./gradlew cC</pre>
</li>
</ol>