Test execution time analysis in JUnit - Test Execution Trace

Test Overview

This test measures how long a simple method takes to execute and verifies that it completes within a set time limit.

Test Code - JUnit 5

JUnit

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertTimeout;
import java.time.Duration;

public class ExecutionTimeTest {

    @Test
    public void testMethodExecutionTime() throws InterruptedException {
        assertTimeout(Duration.ofMillis(500), () -> {
            // Simulate some work with sleep
            Thread.sleep(300);
        });
    }
}

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	Test starts	JUnit test runner initialized	-	PASS
2	JUnit invokes testMethodExecutionTime()	Inside test method	-	PASS
3	assertTimeout starts timer and runs lambda	Timer running, lambda executing	-	PASS
4	Lambda executes Thread.sleep(300) to simulate work	Thread sleeping for 300 milliseconds	-	PASS
5	Lambda completes, assertTimeout checks elapsed time	Elapsed time measured	Elapsed time <= 500 milliseconds	PASS
6	Test finishes successfully within time limit	Test passed	Test execution time is acceptable	PASS

Failure Scenario

Failing Condition: The simulated work takes longer than 500 milliseconds

Execution Trace Quiz - 3 Questions

What does assertTimeout verify in this test?

A That the code finishes within the specified time limit

B That the code throws an exception

C That the code returns a specific value

D That the code runs on a separate thread

Key Result

Use assertTimeout to catch slow code early and keep tests fast and reliable.