Espresso: Thread.sleep( )

Thanks to AlexK for his awesome answer. There are cases that you need to make some delay in code. It is not necessarily waiting for server response but might be waiting for animation to get done. I personally have problem with Espresso idolingResources (I think we are writing many lines of code for a simple thing) so I changed the way AlexK was doing into following code:

/**
 * Perform action of waiting for a specific time.
 */
public static ViewAction waitFor(final long millis) {
    return new ViewAction() {
        @Override
        public Matcher<View> getConstraints() {
            return isRoot();
        }

        @Override
        public String getDescription() {
            return "Wait for " + millis + " milliseconds.";
        }

        @Override
        public void perform(UiController uiController, final View view) {
            uiController.loopMainThreadForAtLeast(millis);
        }
    };
}

So you can create a Delay class and put this method in it in order to access it easily. You can use it in your Test class same way: onView(isRoot()).perform(waitFor(5000));

I think it's more easy to add this line:

SystemClock.sleep(1500);

Waits a given number of milliseconds (of uptimeMillis) before returning. Similar to sleep(long), but does not throw InterruptedException; interrupt() events are deferred until the next interruptible operation. Does not return until at least the specified number of milliseconds has elapsed.

On my mind correct approach will be:

/** Perform action of waiting for a specific view id. */
public static ViewAction waitId(final int viewId, final long millis) {
    return new ViewAction() {
        @Override
        public Matcher<View> getConstraints() {
            return isRoot();
        }

        @Override
        public String getDescription() {
            return "wait for a specific view with id <" + viewId + "> during " + millis + " millis.";
        }

        @Override
        public void perform(final UiController uiController, final View view) {
            uiController.loopMainThreadUntilIdle();
            final long startTime = System.currentTimeMillis();
            final long endTime = startTime + millis;
            final Matcher<View> viewMatcher = withId(viewId);

            do {
                for (View child : TreeIterables.breadthFirstViewTraversal(view)) {
                    // found view with required ID
                    if (viewMatcher.matches(child)) {
                        return;
                    }
                }

                uiController.loopMainThreadForAtLeast(50);
            }
            while (System.currentTimeMillis() < endTime);

            // timeout happens
            throw new PerformException.Builder()
                    .withActionDescription(this.getDescription())
                    .withViewDescription(HumanReadables.describe(view))
                    .withCause(new TimeoutException())
                    .build();
        }
    };
}

And then pattern of usage will be:

// wait during 15 seconds for a view
onView(isRoot()).perform(waitId(R.id.dialogEditor, TimeUnit.SECONDS.toMillis(15)));

I stumbled upon this thread when looking for an answer to a similar problem where I was waiting for a server response and changing visibility of elements based on response.

Whilst the solution above definitely helped, I eventually found this excellent example from chiuki and now use that approach as my go-to whenever I'm waiting for actions to occur during app idle periods.

I've added ElapsedTimeIdlingResource() to my own utilities class, can now effectively use that as an Espresso-proper alternative, and now usage is nice and clean:

// Make sure Espresso does not time out
IdlingPolicies.setMasterPolicyTimeout(waitingTime * 2, TimeUnit.MILLISECONDS);
IdlingPolicies.setIdlingResourceTimeout(waitingTime * 2, TimeUnit.MILLISECONDS);

// Now we wait
IdlingResource idlingResource = new ElapsedTimeIdlingResource(waitingTime);
Espresso.registerIdlingResources(idlingResource);

// Stop and verify
onView(withId(R.id.toggle_button))
    .check(matches(withText(R.string.stop)))
    .perform(click());
onView(withId(R.id.result))
    .check(matches(withText(success ? R.string.success: R.string.failure)));

// Clean up
Espresso.unregisterIdlingResources(idlingResource);