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Device Configuration

Robolectric makes it easy to simulate a variety of device configurations. In particular, the properties that make up the Configuration class can be specified at the test method, test class, package, or suite level, as described here.

Specifying device configuration

The Android device configuration can be specified using the qualifiers @Config argument:

@Test
@Config(qualifiers = "fr-rFR-w360dp-h640dp-xhdpi")
public void testItOnFrenchNexus5() {
}

@Test
@Config(qualifiers = "fr-rFR-w360dp-h640dp-xhdpi")
fun testItOnFrenchNexus5() {
}

From version 3.6 on, Robolectric parses the qualifiers property according to the rules set forth here (but with no preceding directory name), and sets up the Android simulation environment with a corresponding configuration. The system's Configuration, Display and DisplayMetrics objects will all reflect the specified configuration, the locale will be set, and appropriate resources will be selected.

For unspecified properties, Robolectric picks consistent values based on the properties that have been specified, or uses default values as follows:

Property Calculated value (if unspecified) Default Other rules
MCC and MNC None None
Language, region, and script (locale) None en-rUS
Layout direction The locale’s layout direction ldltr
Smallest width The smallest of width and height sw320dp
Width If screen size is specified, the corresponding width as declared here w320dp If screen orientation is specified, width and height will be swapped as appropriate
Height If screen size is specified, the corresponding height as declared here. If screen aspect is specified as long, the height is increased by 25%. h470dp If screen orientation is specified, width and height will be swapped as appropriate
Screen size If height and width are specified, the corresponding screen size as declared here normal
Screen aspect If width and height are specified, long will be used if the ratio of height to width is at least 1.75 notlong
Round screen If UI mode is watch then round notround
Wide color gamut None nowidecg
High dynamic range None lowdr
Screen orientation If width and height are specified, port or land as appropriate port
UI mode None normal, except this property isn't included in the qualifier list
Night mode None notnight
Screen pixel density None mdpi
Touchscreen type None finger
Keyboard availability None keyssoft
Primary text input method None nokeys
Navigation key availability None navhidden
Primary non-touch navigation method None nonav
Platform version The SDK level currently active. Need not be specified.

Cumulative qualifiers

By default, specifying qualifiers causes any previous specification of qualifiers to be ignored. For example, qualifiers at the test method level occlude qualifiers at the test class level. However, if the qualifiers config property starts with a + (plus sign), it is interpreted as an overlay to any higher-level qualifiers that have been specified:

@Config(qualifiers = "xlarge-port")
public class MyTest {
  @Test
  public void testItWithXlargePort() {
    // Config is "xlarge-port"
  }

  @Test
  @Config(qualifiers = "+land")
  public void testItWithXlargeLand() {
    // Config is "xlarge-land"
  }

  @Test
  @Config(qualifiers = "land")
  public void testItWithLand() {
    // Config is "normal-land"
  }
}

@Config(qualifiers = "xlarge-port")
class MyTest {
  @Test
  fun testItWithXlargePort() {
    // Config is "xlarge-port"
  }

  @Test
  @Config(qualifiers = "+land")
  fun testItWithXlargeLand() {
    // Config is "xlarge-land"
  }

  @Test
  @Config(qualifiers = "land")
  fun testItWithLand() {
    // Config is "normal-land"
  }
}

Values for unspecified properties are calculated, and rules are applied, after all configs have been merged.

Changing device configuration

The device configuration can be changed within a test using RuntimeEnvironment.setQualifiers():

@Test
@Config(qualifiers = "+port")
public void testOrientationChange() {
  MyActivity controller = Robolectric.buildActivity(MyActivity.class);
  controller.setup();
  // assert that activity is in portrait mode
  RuntimeEnvironment.setQualifiers("+land");
  controller.configurationChange();
  // assert that activity is in landscape mode
}

@Test
@Config(qualifiers = "+port")
fun testOrientationChange() {
  val controller = Robolectric.buildActivity(MyActivity::class)
  controller.setup()
  // assert that activity is in portrait mode
  RuntimeEnvironment.setQualifiers("+land")
  controller.configurationChange()
  // assert that activity is in landscape mode
}

The string parameter to RuntimeEnvironment.setQualifiers() has the same rules as Config.qualifiers.

Note that RuntimeEnvironment.setQualifiers() updates the system and application resources with the new configuration, but does not trigger any action on extant activities or other components. ActivityController.configurationChange() can be used to simulate the sequence of events that take place on a device when its configuration changes.

If the Activity is configured to handle the configuration changes, ActivityController.configurationChange() will call the Activity’s onConfigurationChanged() method. If not, ActivityController destroys and recreates the Activity.

Simulating displays

Robolectric allows display properties to be changed during a test using setters on ShadowDisplay. Multiple displays can be simulated using APIs on ShadowDisplayManager.