The resources/generic-sensor-helpers.js tests require an implementation of the GenericSensorTest interface, which should emulate platform sensor backends. The GenericSensorTest interface is defined as:

  class MockSensor {
    // Sets fake data that is used to deliver sensor reading updates.
    async setSensorReading(FrozenArray<double> readingData);
    setStartShouldFail(boolean shouldFail); // Sets flag that forces sensor to fail.
    getSamplingFrequency(); // Return the sampling frequency.
  };

  class MockSensorProvider {
    // Sets flag that forces mock SensorProvider to fail when getSensor() is
    // invoked.
    setGetSensorShouldFail(DOMString sensorType, boolean shouldFail);
    // Sets flag that forces mock SensorProvider to permissions denied when
    // getSensor() is invoked.
    setPermissionsDenied(DOMString sensorType, boolean permissionsDenied);
    getCreatedSensor(DOMString sensorType); // Return `MockSensor` interface.
    setMaximumSupportedFrequency(double frequency); // Sets the maximum frequency.
    setMinimumSupportedFrequency(double frequency); // Sets the minimum frequency.
  }

  class GenericSensorTest {
    initialize();  // Sets up the testing environment.
    async reset(); // Frees the resources.
    getSensorProvider(); // Returns `MockSensorProvider` interface.
  };

The Chromium implementation of the GenericSensorTest interface is located in generic_sensor_mocks.js.

Other browser vendors should provide their own implementations of the GenericSensorTest interface.

Known issue: a WebDriver extension is a better approach for the Generic Sensor tests automation.