How to run unit test + Espresso repeatedly?

Issue

I need to collect some data on my current app in order to analyse performance speed by checking the average ellapsed time during Activity start up. I would like to run a test battery where the activity is started 10, 100, 1000 and 5000 times. For each test, it should remain open for at least 10 seconds (time needed to collect all data that happens asynchronously). What I want is exactly this behaviour without having to write these many methods:

@RunWith(AndroidJUnit4.class)
@LargeTest
public class TestStreamLoadingPerformance {

    private static final long TIME_OUT = 2;
    private static final long WAITING_TIME = 10000;

    @Rule
    public ActivityTestRule mActivityRule = new ActivityTestRule(HomepageActivity.class);

    private ElapsedTimeIdlingResource mIdleRes = new ElapsedTimeIdlingResource(WAITING_TIME);


    @Before
    public void setUp() {
        IdlingPolicies.setMasterPolicyTimeout(TIME_OUT, TimeUnit.HOURS);
        IdlingPolicies.setIdlingResourceTimeout(TIME_OUT, TimeUnit.HOURS);
        Espresso.registerIdlingResources(mIdleRes);
    }

    @After
    public void tearDown() {
        Espresso.unregisterIdlingResources(mIdleRes);
    }

    @Test
    public void test01() {
    }

    @Test
    public void test02() {
    }

    @Test
    public void test03() {
    }

    @Test
    public void test04() {
    }

    @Test
    public void test05() {
    }

    @Test
    public void test06() {
    }

    @Test
    public void test07() {
    }

    @Test
    public void test08() {
    }

    @Test
    public void test09() {
    }
}

Solution

With the help of @Be_negative comments, this blog post and this answer, I was able to solve the problem with the code below:

@RunWith(AndroidJUnit4.class)
@LargeTest
public class TestStreamLoadingPerformance {

    @Rule
    public ActivityTestRule mActivityRule = new ActivityTestRule(HomepageActivity.class, false, false);
    @Rule
    public RepeatRule mRepeatRule = new RepeatRule();


    @After
    public void tearDown() {
        closeActivity();
    }

    private void closeActivity() {
        final int N = 10;
        try {
            for (int i = 0; i < N; i++) {
                Espresso.pressBack();
            }
        } catch (NoActivityResumedException e) {
            Log.e(TestStreamLoadingPerformance.class.getSimpleName(), "Unable to close activities", e);
        }
    }

    @Test
    @RepeatRule.Repeat(times = 10)
    public void collectData() {
        mActivityRule.launchActivity(null);
    }
}

import org.junit.rules.TestRule;
import org.junit.runner.Description;
import org.junit.runners.model.Statement;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

public class RepeatRule implements TestRule {
    @Retention(RetentionPolicy.RUNTIME)
    @Target({
            java.lang.annotation.ElementType.METHOD
    })
    public @interface Repeat {
        public abstract int times();
    }

    private static class RepeatStatement extends Statement {

        private final int times;
        private final Statement statement;

        private RepeatStatement(int times, Statement statement) {
            this.times = times;
            this.statement = statement;
        }

        @Override
        public void evaluate() throws Throwable {
            for (int i = 0; i < times; i++) {
                statement.evaluate();
            }
        }
    }

    @Override
    public Statement apply(Statement statement, Description description) {
        Statement result = statement;
        Repeat repeat = description.getAnnotation(Repeat.class);
        if (repeat != null) {
            int times = repeat.times();
            result = new RepeatStatement(times, statement);
        }
        return result;
    }
}

Answered By - E. Fernandes