Espresso Idling Resource that waits until either a certain condition is met or a given time has passed

ConditionalTimeoutIdlingResource.java

import android.support.test.espresso.IdlingResource;

public class ConditionalTimeoutIdlingResource implements IdlingResource {

    private final long startTime;
    private final long waitingTime;
    private ResourceCallback resourceCallback;
    private ConditionalResourceCallback conditionalResourceCallback = new ConditionalResourceCallback() {
        @Override
        public boolean meetsCondition() {
            return false; // default
        }
    };

    public ConditionalTimeoutIdlingResource(long waitingTime) {
        this.startTime = System.currentTimeMillis();
        this.waitingTime = waitingTime;
    }

    @Override
    public String getName() {
        return ConditionalTimeoutIdlingResource.class.getName() + ":" + waitingTime;
    }

    @Override
    public boolean isIdleNow() {
        long elapsed = System.currentTimeMillis() - startTime;
        boolean idle = elapsed >= waitingTime || conditionalResourceCallback.meetsCondition();
        if (idle) {
            resourceCallback.onTransitionToIdle();
        }
        return idle;
    }

    @Override
    public void registerIdleTransitionCallback(ResourceCallback resourceCallback) {
        this.resourceCallback = resourceCallback;
    }

    public void registerConditionalTransitionCallback(ConditionalResourceCallback conditionalResourceCallback) {
        this.conditionalResourceCallback = conditionalResourceCallback;
    }

    public interface ConditionalResourceCallback {
        boolean meetsCondition();
    }
}