Testing Using Mock Locations

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To test a location-aware app that uses Location Services, you don't need to move your device from place to place to generate location data. Instead, you can put Location Services into mock mode. In this mode, you can send mock Location objects to Location Services, which then sends them to location clients. In mock mode, Location Services also uses mock Location objects to trigger geofences.

Using mock locations has several advantages:

  • Mock locations allow you to create specific mock data, instead of trying to approximate data by moving an actual device.
  • Since mock locations come from Location Services, they test every part of your location-handling code. In addition, since you can send the mock data from outside your production app, you don't have to disable or remove test code before you publish.
  • Since you don't have to generate test locations by moving a device, you can test an app using the emulator.

The best way to use mock locations is to send them from a separate mock location provider app. This lesson includes a provider app that you can download and use to test your own software. Modify the provider app as necessary to suit your own needs. Some ideas for providing test data to the app are listed in the section Managing test data.

The remainder of this lesson shows you how to turn on mock mode and use a location client to send mock locations to Location Services.

Note: Mock locations have no effect on the activity recognition algorithm used by Location Services. To learn more about activity recognition, see the lesson Recognizing the User's Current Activity.

Turn On Mock Mode

To send mock locations to Location Services in mock mode, a test app must request the permission ACCESS_MOCK_LOCATION. In addition, you must enable mock locations on the test device using the option Enable mock locations. To learn how to enable mock locations on the device, see Setting up a Device for Development.

To turn on mock mode in Location Services, start by connecting a location client to Location Services, as described in the lesson Retrieving the Current Location. Next, call the method LocationClient.setMockMode(true). Once you call this method, Location Services turns off its internal location providers and only sends out the mock locations you provide it. The following snippet shows you how to call LocationClient.setMockMode(true): 

    // Define a LocationClient object
    public LocationClient mLocationClient;
    ...
    // Connect to Location Services
    mLocationClient.connect();
    ...
    // When the location client is connected, set mock mode
    mLocationClinet.setMockMode(true);

Once you have connected the location client to Location Services, you must keep it connected until you finish sending out mock locations. Once you call LocationClient.disconnect(), Location Services returns to using its internal location providers. To turn off mock mode while the location client is connected, call LocationClient.setMockMode(false).

Send Mock Locations

Once you have set mock mode, you can create mock Location objects and send them to Location Services. In turn, Location Services sends these mock Location objects to connected location clients. Location Services also uses the mock Location objects to control geofence triggering.

To create a new mock Location, create a new Location object using your test data. Always set the provider value to flp, which is the code that Location Services puts into the Location objects it sends out. The following snippet shows you how to create a new mock Location: 

    private static final String PROVIDER = "flp";
    private static final double LAT = 37.377166;
    private static final double LNG = -122.086966;
    private static final float ACCURACY = 3.0f;
    ...
    /*
     * From input arguments, create a single Location with provider set to
     * "flp"
     */
    public Location createLocation(double lat, double lng, float accuracy) {
        // Create a new Location
        Location newLocation = new Location(PROVIDER);
        newLocation.setLatitude(lat);
        newLocation.setLongitude(lng);
        newLocation.setAccuracy(accuracy);
        return newLocation;
    }
    ...
    // Example of creating a new Location from test data
    Location testLocation = createLocation(LAT, LNG, ACCURACY);

In mock mode, to send a mock location to Location Services call the method LocationClient.setMockLocation(). For example: 

    mLocationClient.setMockLocation(testLocation);

Location Services sets this mock location as the current location, and this location is sent out as the next location update. If this new mock location moves across a geofence boundary, Location Services triggers the geofence.

Run the Mock Location Provider App

This section contains a brief overview of the mock location provider sample app (available for download above) and gives you directions for testing an app using the sample app.

Overview

The mock location provider app included with this lesson sends mock Location objects to Location Services from a background thread running in a started Service. By using a started service, the provider app is able to keep running even if the app's main Activity is destroyed because of a configuration change or other system event. By using a background thread, the service is able to perform a long-running test without blocking the UI thread.

The Activity that starts when you run the provider app allows you to send test parameters to the Service and control the type of test you want. You have the following options:

Pause before test
The number of seconds to wait before the provider app starts sending test data to Location Services. This interval allows you to switch from the provider app to the app under test before the testing actually starts.
Send interval
The number of seconds that the provider app waits before it sends another mock location to Location Services. See the section Testing Tips to learn more about setting the send interval.
Run once
Switch from normal mode to mock mode, run through the test data once, switch back to normal mode, and then kill the Service.
Run continuously
Switch from normal mode to mock mode, then run through the test data indefinitely. The background thread and the started Service continue to run, even if the main Activity is destroyed.
Stop test
If a continuous test is in progress, stop it; otherwise, return a warning message. The started Service switches from mock mode to normal mode and then stops itself. This also stops the background thread.

Besides the options, the provider app has two status displays:

App status
Displays messages related to the lifecycle of the provider app.
Connection status
Displays messages related to the state of the location client connection.

While the started Service is running, it also posts notifications with the testing status. These notifications allow you to see status updates even if the app is not in the foreground. When you click on a notification, the main Activity of the provider app returns to the foreground.

Test using the mock location provider app

To test mock location data coming from the mock location provider app:

  1. Install the mock location provider app on a device that has Google Play services installed. Location Services is part of Google Play services.
  2. On the device, enable mock locations. To learn how to do this, see the topic Setting up a Device for Development.
  3. Start the provider app from the Launcher, then choose the options you want from the main screen.
  4. Unless you've removed the pause interval feature, the mock location provider app pauses for a few seconds, and then starts sending mock location data to Location Services.
  5. Run the app you want to test. While the mock location provider app is running, the app you're testing receives mock locations instead of real locations.
  6. If the provider app is in the midst of a continuous test, you can switch back to real locations by clicking Stop test. This forces the started Service to turn off mock mode and then stop itself. When the service stops itself, the background thread is also destroyed.

Testing Tips

The following sections contain tips for creating mock location data and using the data with a mock location provider app.

Choosing a send interval

Each location provider that contributes to the fused location sent out by Location Services has its own minimum update cycle. For example, the GPS provider can't send a new location more often than once per second, and the Wi-Fi provider can't send a new location more often than once every five seconds. These cycle times are handled automatically for real locations, but you should account for them when you send mock locations. For example, you shouldn't send a new mock location more than once per second. If you're testing indoor locations, which rely heavily on the Wi-Fi provider, then you should consider using a send interval of five seconds.

Simulating speed

To simulate the speed of an actual device, shorten or lengthen the distance between two successive locations. For example, changing the location by 88 feet every second simulates car travel, because this change works out to 60 miles an hour. In comparison, changing the location by 1.5 feet every second simulates brisk walking, because this change works out to 3 miles per hour.

Calculating location data

By searching the web, you can find a variety of small programs that calculate a new set of latitude and longitude coordinates from a starting location and a distance, as well as references to formulas for calculating the distance between two points based on their latitude and longitude. In addition, the Location class offers two methods for calculating the distance between points:

distanceBetween()
A static method that calculates the distance between two points specified by latitude and longitude.
distanceTo()
For a given Location, returns the distance to another Location.

Geofence testing

When you test an app that uses geofence detection, use test data that reflects different modes of travel, including walking, cycling, driving, and traveling by train. For a slow mode of travel, make small changes in position between points. Conversely, for a fast mode of travel, make a large change in position between points.

Managing test data

The mock location provider app included with this lesson contains test latitude, longitude, and accuracy values in the form of constants. You may want to consider other ways of organizing data as well:

XML
Store location data in XML files that are including in the provider app. By separating the data from the code, you facilitate changes to the data.
Server download
Store location data on a server and then have the provider app download it. Since the data is completely separate from the app, you can change the data without having to rebuild the app. You can also change the data on the server and have the changes reflected immediately in the mock locations you're testing.
Recorded data
Instead of making up test data, write a utility app that records location data as you move the device. Use the recorded data as your test data, or use the data to guide you in developing test data. For example, record locations as you walk with a device, and then create mock locations that have an appropriate change in latitude and longitude over time.
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