Unit testing services in Microservices - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main goal of unit testing in microservices?

To verify that each individual service component works correctly in isolation, ensuring its logic is correct before integration.

beginner

Why should unit tests avoid calling external services or databases?

Because unit tests should be fast, reliable, and isolated. Calling external services makes tests slower and less predictable.

intermediate

What technique is commonly used to isolate dependencies in unit testing microservices?

Mocking or stubbing dependencies to simulate their behavior without invoking real implementations.

intermediate

How does unit testing contribute to the scalability of microservices?

By catching bugs early in small components, unit testing reduces errors in production and supports easier scaling of individual services.

beginner

What is a good practice for naming unit tests in microservices?

Use descriptive names that clearly state the condition and expected outcome, like 'shouldReturnErrorWhenInputIsInvalid'.

What is the primary focus of unit testing in microservices?

A Testing user interface responsiveness

B Testing the entire system end-to-end

C Testing network latency between services

D Testing individual service components in isolation

Unit testing focuses on verifying small parts of the system independently, not the whole system or network.

Which of the following is NOT a reason to mock dependencies in unit tests?

A To test real database performance

B To speed up test execution

C To isolate the unit under test

D To avoid flaky tests caused by external services

Unit tests should not test real database performance; that is for integration or performance tests.

What is a sign of a well-written unit test?

A It clearly describes the tested behavior and runs quickly

B It depends on multiple external services

C It runs slowly and intermittently fails

D It tests multiple services at once

Good unit tests are fast, reliable, and clearly describe what they test.

Which tool or technique is commonly used to simulate dependencies in unit tests?

A Profiling

B Load testing

C Mocking

D Logging

Mocking replaces real dependencies with fake ones to isolate the unit under test.

Why is unit testing important before integration testing in microservices?

A It tests the entire system's user interface

B It ensures individual parts work correctly, reducing integration errors

C It measures network bandwidth

D It replaces the need for integration testing

Unit testing verifies components individually, making integration smoother and less error-prone.

Explain how mocking helps in unit testing microservices and why it is important.

Think about how you can test a part without involving others.

Describe best practices for writing effective unit tests for microservices.

Imagine explaining to a friend how to write a good test.