The file containing the source code shown below is located in the corresponding directory in <sdk>/samples/android-<version>/...
/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.android.example.spinner.test;
import com.android.example.spinner.SpinnerActivity;
import android.app.Instrumentation;
import android.test.ActivityInstrumentationTestCase2;
import android.test.UiThreadTest;
import android.view.KeyEvent;
import android.widget.Spinner;
import android.widget.SpinnerAdapter;
import android.widget.TextView;
/*
 * Tests the example application Spinner. Uses the instrumentation test class
 * ActivityInstrumentationTestCase2 as its base class. The tests include
 *   - test initial conditions
 *   - test the UI
 *   - state management - preserving state after the app is shut down and restarted, preserving
 *     state after the app is hidden (paused) and re-displayed (resumed)
 *
 * Demonstrates the use of JUnit setUp() and assert() methods.
 */
public class SpinnerActivityTest extends ActivityInstrumentationTestCase2<SpinnerActivity> {
    // Number of items in the spinner's backing mLocalAdapter
    public static final int ADAPTER_COUNT = 9;
    // The location of Saturn in the backing mLocalAdapter array (0-based)
    public static final int TEST_POSITION = 5;
    // Set the initial position of the spinner to zero
    public static final int INITIAL_POSITION = 0;
    // The initial position corresponds to Mercury
    public static final String INITIAL_SELECTION = "Mercury";
    // Test values of position and selection for the testStateDestroy test
    public static final int TEST_STATE_DESTROY_POSITION = 2;
    public static final String TEST_STATE_DESTROY_SELECTION = "Earth";
    // Test values of position and selection for the testStatePause test
    public static final int TEST_STATE_PAUSE_POSITION = 4;
    public static final String TEST_STATE_PAUSE_SELECTION = "Jupiter";
    // The Application object for the application under test
    private SpinnerActivity mActivity;
    // String displayed in the spinner in the app under test
    private String mSelection;
    // The currently selected position in the spinner in the app under test
    private int mPos;
    /*
     *  The Spinner object in the app under test. Used with instrumentation to control the
     *  app under test.
     */
    private Spinner mSpinner;
    /*
     * The data backing the Spinner in the app under test.
     */
    private SpinnerAdapter mPlanetData;
    /*
     * Constructor for the test class. Required by Android test classes. The constructor
     * must call the super constructor, providing the Android package name of the app under test
     * and the Java class name of the activity in that application that handles the MAIN intent.
     */
    public SpinnerActivityTest() {
        super("com.android.example.spinner", SpinnerActivity.class);
    }
    /*
     * Sets up the test environment before each test.
     * @see android.test.ActivityInstrumentationTestCase2#setUp()
     */
    @Override
    protected void setUp() throws Exception {
        /*
         * Call the super constructor (required by JUnit)
         */
        super.setUp();
        /*
         * prepare to send key events to the app under test by turning off touch mode.
         * Must be done before the first call to getActivity()
         */
        setActivityInitialTouchMode(false);
        /*
         * Start the app under test by starting its main activity. The test runner already knows
         * which activity this is from the call to the super constructor, as mentioned
         * previously. The tests can now use instrumentation to directly access the main
         * activity through mActivity.
         */
        mActivity = getActivity();
        /*
         * Get references to objects in the application under test. These are
         * tested to ensure that the app under test has initialized correctly.
         */
        mSpinner = (Spinner)mActivity.findViewById(com.android.example.spinner.R.id.Spinner01);
        mPlanetData = mSpinner.getAdapter();
    }
    /*
     * Tests the initial values of key objects in the app under test, to ensure the initial
     * conditions make sense. If one of these is not initialized correctly, then subsequent
     * tests are suspect and should be ignored.
     */
    public void testPreconditions() {
        /*
         *  An example of an initialization test. Assert that the item select listener in
         *  the main Activity is not null (has been set to a valid callback)
         */
        assertTrue(mSpinner.getOnItemSelectedListener() != null);
        /*
         * Test that the spinner's backing mLocalAdapter was initialized correctly.
         */
        assertTrue(mPlanetData != null);
        /*
         *  Also ensure that the backing mLocalAdapter has the correct number of entries.
         */
        assertEquals(mPlanetData.getCount(), ADAPTER_COUNT);
    }
    /*
     * Tests the UI of the main activity. Sends key events (keystrokes) to the UI, then checks
     * if the resulting spinner state is consistent with the attempted selection.
     */
    public void testSpinnerUI() {
        /*
         * Request focus for the spinner widget in the application under test,
         * and set its initial position. This code interacts with the app's View
         *  so it has to run on the app's thread not the test's thread.
         *
         * To do this, pass the necessary code to the application with
         * runOnUiThread(). The parameter is an anonymous Runnable object that
         * contains the Java statements put in it by its run() method.
         */
        mActivity.runOnUiThread(
            new Runnable() {
                public void run() {
                    mSpinner.requestFocus();
                    mSpinner.setSelection(INITIAL_POSITION);
                }
            }
        );
        // Activate the spinner by clicking the center keypad key
        this.sendKeys(KeyEvent.KEYCODE_DPAD_CENTER);
        // send 5 down arrow keys to the spinner
        for (int i = 1; i <= TEST_POSITION; i++) {
            this.sendKeys(KeyEvent.KEYCODE_DPAD_DOWN);
        }
        // select the item at the current spinner position
        this.sendKeys(KeyEvent.KEYCODE_DPAD_CENTER);
        // get the position of the selected item
        mPos = mSpinner.getSelectedItemPosition();
        /*
         * from the spinner's data mLocalAdapter, get the object at the selected position
         * (this is a String value)
         */
        mSelection = (String)mSpinner.getItemAtPosition(mPos);
        /*
         * Get the TextView widget that displays the result of selecting an item from the spinner
         */
        TextView resultView =
                (TextView) mActivity.findViewById(com.android.example.spinner.R.id.SpinnerResult);
        // Get the String value in the EditText object
        String resultText = (String) resultView.getText();
        /*
         * Confirm that the EditText contains the same value as the data in the mLocalAdapter
         */
        assertEquals(resultText,mSelection);
    }
    /*
     *  Tests that the activity under test maintains the spinner state when the activity halts
     *  and then restarts (for example, if the device reboots). Sets the spinner to a
     *  certain state, calls finish() on the activity, restarts the activity, and then
     *  checks that the spinner has the same state.
     *
     */
    public void testStateDestroy() {
        /*
         * Set the position and value of the spinner in the Activity. The test runner's
         * instrumentation enables this by running the test app and the main app in the same
         * process.
         */
        mActivity.setSpinnerPosition(TEST_STATE_DESTROY_POSITION);
        mActivity.setSpinnerSelection(TEST_STATE_DESTROY_SELECTION);
        // Halt the Activity by calling Activity.finish() on it
        mActivity.finish();
        // Restart the activity by calling ActivityInstrumentationTestCase2.getActivity()
        mActivity = this.getActivity();
        /*
         * Get the current position and selection from the activity.
         */
        int currentPosition = mActivity.getSpinnerPosition();
        String currentSelection = mActivity.getSpinnerSelection();
        // test that they are the same.
        assertEquals(TEST_STATE_DESTROY_POSITION, currentPosition);
        assertEquals(TEST_STATE_DESTROY_SELECTION, currentSelection);
    }
    /*
     * Tests that the activity under test maintains the spinner's state when the activity is
     * paused and then resumed.
     *
     * Calls the activity's onResume() method. Changes the spinner's state by
     * altering the activity's View. This means the test must run
     * on the UI Thread. All the statements in the test method may be run on
     * that thread, so instead of using the runOnUiThread() method, the
     * @UiThreadTest is used.
     */
    @UiThreadTest
    public void testStatePause() {
        /*
         * Get the instrumentation object for this application. This object
         * does all the instrumentation work for the test runner
         */
        Instrumentation instr = this.getInstrumentation();
        /*
         * Set the activity's fields for the position and value of the spinner
         */
        mActivity.setSpinnerPosition(TEST_STATE_PAUSE_POSITION);
        mActivity.setSpinnerSelection(TEST_STATE_PAUSE_SELECTION);
        /*
         *  Use the instrumentation to onPause() on the currently running Activity.
         *  This analogous to calling finish() in the testStateDestroy() method.
         *  This way demonstrates using the test class' instrumentation.
         */
        instr.callActivityOnPause(mActivity);
        /*
         * Set the spinner to a test position
         */
        mActivity.setSpinnerPosition(0);
        mActivity.setSpinnerSelection("");
        /*
         * Call the activity's onResume() method. This forces the activity
         * to restore its state.
         */
        instr.callActivityOnResume(mActivity);
        /*
         * Get the current state of the spinner
         */
        int currentPosition = mActivity.getSpinnerPosition();
        String currentSelection = mActivity.getSpinnerSelection();
        assertEquals(TEST_STATE_PAUSE_POSITION,currentPosition);
        assertEquals(TEST_STATE_PAUSE_SELECTION,currentSelection);
  }
}