Three parts of a test

This learning hour is about Arrange - Act - Assert and uses a simpler exercise than AAA.

Learning Goals

• recognize a well-structured test case.
• use the three parts when designing a test case.

Session Outline

• 5 min connect: What is an automated unit test
• 10 min concept: Three parts of a test
• 35 min concrete: Write some tests
• 5 min conclusions: When to do this

Connect: Three facts

What is an automated unit test? Give me three facts about it.

Concept: Three parts of a test

An automated test usually has three kinds of code.

• Arrange - set up the test data and environment your function will need
• Act - exercise the function you want to test
• Assert - verify it did the right thing by checking what happened

Normally in a unit test you only have one of each section, and they come in that order. If you want to check another thing, add a new test case. Don’t just build more act-assert steps onto the same test case.

Concrete

Write some test cases for some existing code that already basically works. For example CalcStats. Be sure to structure your test cases using Arrange - Act - Assert. If you find any bugs in the code, please fix them.

Conclusions

Can you think of any advantages of structuring your tests this way, with Arrange - Act - Assert? Are there any situations where it wouldn’t be a good idea? When should you use this?