docs/html/training/testing/integration-testing/content-provider-testing.jd

page.title=Testing Your Content Provider
page.tags=testing, content provider
trainingnavtop=true

@jd:body

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  <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>
    <li><a href="{@docRoot}tools/studio/index.html">Android Studio 1.4.1 or higher</a>.</li>
  </ul>

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

  <ol>
    <li><a href="#build">Create Integration Tests for Content Providers</a></li>
    <li><a href="#WhatToTest">What to Test</a></li>
  </ol>

  <h2>You should also read</h2>
  <ul>
      <li><a href="{@docRoot}guide/topics/providers/content-providers.html">Content Providers</a>
      </li>
  </ul>
</div>
</div>

<p>
    If you are implementing a <a href="{@docRoot}guide/topics/providers/content-providers.html">
    content provider</a> to store and retrieve data or to make data
    accessible to other apps, you should test your provider to ensure that it doesn't behave in an
    unexpected way. This lesson describes how to test public content providers, and is also
    applicable to providers that you keep private to your own app.
</p>
<h2 id="build">Create Integration Tests for Content Providers</h2>
<p>
In Android, apps view content providers as data APIs that provide
tables of data, with their internals hidden from view. A content provider may have many
public constants, but it usually has few if any public methods and no public variables.
For this reason, you should write your tests based only on the provider's public members.
A content provider that is designed like this is offering a contract between itself and its users.
</p>
<p>
Content providers let you access actual user data, so it's important to ensure
that you test the content provider in an isolated testing environment. This approach allows you to
only run against data dependencies set explicitly in the test case. It also means that your tests
do not modify actual user data. For example, you should avoid writing a test that fails because
there was data left over from a previous test. Similarly, your test should avoid adding or deleting
actual contact information in a provider.
</p>

<p>
To test your content provider in isolation, use the {@link android.test.ProviderTestCase2} class.
This class allows you to use Android mock object classes such as {@link android.test.IsolatedContext}
and {@link android.test.mock.MockContentResolver} to access file and database information without
affecting the actual user data.
</p>

<p>Your integration test should be written as a JUnit 4 test class. To learn more about creating
JUnit 4 test classes and using JUnit 4 assertions, see
<a href="{@docRoot}training/testing/unit-testing/local-unit-tests.html#build">
Create a Local Unit Test Class</a>.</p>

<p>To create an integration test for your content provider, you must perform these steps:</p>
<ul>
    <li>Create your test class as a subclass of {@link android.test.ProviderTestCase2}.</li>
    <li>Add the
{@code &#64;RunWith(AndroidJUnit4.class)} annotation at the beginning of your test class
definition.</li>
    <li>Specify the
<a href="{@docRoot}reference/android/support/test/runner/AndroidJUnitRunner.html">
{@code AndroidJUnitRunner}</a> class that the
<a href="{@docRoot}tools/testing-support-library/index.html">Android Testing Support Library</a>
provides as your default test runner. This step is described in more detail in
<a href="{@docRoot}training/testing/start/index.html#run-instrumented-tests">
Getting Started with Testing</a>.</li>
    <li>Set the {@link android.content.Context} object from the
<a href="{@docRoot}reference/android/support/test/InstrumentationRegistry.html">
{@code InstrumentationRegistry}</a> class. See the snippet below for an example.
    <pre>
&#64;Override
protected void setUp() throws Exception {
    setContext(InstrumentationRegistry.getTargetContext());
    super.setUp();
}</pre>
    </li>
</ul>

<h3 id="ProviderTestCase2">How ProviderTestCase2 works</h3>
<p>
    You test a provider with a subclass of {@link android.test.ProviderTestCase2}. This base class
    extends {@link android.test.AndroidTestCase}, so it provides the JUnit testing framework as well
    as Android-specific methods for testing application permissions. The most important
    feature of this class is its initialization, which creates the isolated test environment.
</p>
<p>
    The initialization is done in the constructor for {@link android.test.ProviderTestCase2}, which
    subclasses call in their own constructors. The {@link android.test.ProviderTestCase2}
    constructor creates an {@link android.test.IsolatedContext} object that allows file and
    database operations but stubs out other interactions with the Android system.
    The file and database operations themselves take place in a directory that is local to the
    device or emulator and has a special prefix.
</p>
<p>
    The constructor then creates a {@link android.test.mock.MockContentResolver} to use as the
    resolver for the test.
</p>
<p>
    Lastly, the constructor creates an instance of the provider under test. This is a normal
    {@link android.content.ContentProvider} object, but it takes all of its environment information
    from the {@link android.test.IsolatedContext}, so it is restricted to
    working in the isolated test environment. All of the tests done in the test case class run
    against this isolated object.
</p>

<p>
You run integration tests for content providers the same way as instrumented unit tests. To run the
integration test for your content provider, follow the steps described in <a
href="{@docRoot}training/testing/unit-testing/instrumented-unit-tests.html#run">
Run Instrumented Unit Tests</a>.
</p>

<h2 id="WhatToTest">What to Test</h2>
<p>
Here are some specific guidelines for testing content providers.
</p>
<ul>
    <li>
        Test with resolver methods: Even though you can instantiate a provider object in
        {@link android.test.ProviderTestCase2}, you should always test with a resolver object
        using the appropriate URI. Doing so ensures that you are testing the provider by performing
        the same interaction that a regular application would use.
    </li>
    <li>
        Test a public provider as a contract: If you intend your provider to be public and
        available to other applications, you should test it as a contract. Some examples of how to
        do so are as follows:
        <ul>
            <li>
                Test with constants that your provider publicly exposes. For
                example, look for constants that refer to column names in one of the provider's
                data tables. These should always be constants publicly defined by the provider.
            </li>
            <li>
                Test all the URIs that your provider offers. Your provider may offer several URIs,
                each one referring to a different aspect of the data.
            </li>
            <li>
                Test invalid URIs: Your unit tests should deliberately call the provider with an
                invalid URI, and look for errors. A good provider design is to throw an
                {@code IllegalArgumentException} for invalid URIs.

            </li>
        </ul>
    </li>
    <li>
        Test the standard provider interactions: Most providers offer six access methods:
        {@code query()}, {@code insert()}, {@code delete()}, {@code update()},
        {@code getType()}, and {@code onCreate()}. Your tests should verify that all
        of these methods work. These methods are described in more detail in the topic
        <a href="{@docRoot}guide/topics/providers/content-providers.html">Content Providers</a>.
    </li>
    <li>
        Test business logic: If the content provider implements business logic, you should test it.
        Business logic includes handling of invalid values, financial or arithmetic calculations,
        elimination or combining of duplicates.
    </li>
</ul>