Facilitation.md

Test anatomy

Learning Goals

• Demystify what are Unit Tests
• Understand the importance of the 3 test parts

Connect - MythBusters

In small groups, categorize each sentence about Unit tests in :

• Myth
• Truth

Sentences

• It makes changes more difficult to make
• Using them, I don't have a piece of code that I'm afraid to touch
• Unit tests are only written by testers
• My code is so simple, so I do not need to write a single test on it
• Unit tested code is of higher quality than not tested code
• You only need unit testing when there are many developers
• It reduces the cost of development
• It takes too much time to write

Correction

Myths

• It makes changes more difficult to make
  • Makes changes easier to make
  • Let developers refactor without fear (again, again, and again)
• Unit tests are only written by testers
  • Usually, they don’t…
  • Developers write unit tests
  • Ideally run them every time they make any change on the system
• My code is so simple, I do not need to write a single test on it
  • Simple code requires simple tests, so there are no excuses.
• You only need unit testing when there are many developers
  • Unit testing can help a one-person team just as much as a 50-person team
  • Even more risky to let a single person hold all the cards
• It takes too much time to write
  • It takes a little while to get used to, but overall will save you time and cut down on wasted time
  • Regression testing will keep things moving forward without having to worry too much
  • How do you test your development if you do not write Unit tests?

Our responsibility is to reduce the cost of quality

Facts

• Using them, I don't have a piece of code that I'm afraid to touch
  • When you refactor / add new features it acts as a safety net and increase your confidence
• Unit tested code is of higher quality than not tested one
  • It identifies every defect that may have come up before code is sent further for integration testing
  • Writing tests makes you think harder about the problem
  • It exposes the edge cases and makes you write better code
• It reduces the cost of development
  • Since the bugs are found early, unit testing helps reduce the cost of bug fixes
  • Bugs detected earlier are easier to fix

Concepts

What is a Unit Test?

A unit test is an automated test that :

• Verifies a small piece of code (also known as a unit)
• Does it quickly
• And does it in an isolated manner.

What makes a successful test suite?

• Integrated into the development cycle
  • Ideally : execute them on every change -Targets the most important parts of your code base
  • Domain model – contains the business logic (gives the best ROI)
• Provides maximum value with minimum maintenance costs
  • Recognizing a valuable test (and, by extension, a test of low value)
  • Writing a valuable test

Complete anatomy

• Name your tests class has a container for a cohesive set of tests

• Don’t follow a rigid naming policy

  • You simply can’t fit a high-level description of a complex behavior into the narrow box of such a policy
  • Allow freedom of expression

• Name the test as if you were describing the scenario to a non-programmer who is familiar with the problem domain

  • A domain expert or a business analyst should understand it

• Use sentences

  • Express a true business specification
  • Doing so helps improve readability, especially in long names

• Test case structuration using Arrange - Act - Assert:

  • helps keep tests readable
  • exposes the tested behavior

Unit Testing is not a secondary activity, it’s the primary one of a good developer !!!

Concrete Practice - Yellow Submarine

Based on previous learning, let's add missing tests on the Submarine. Follow instructions here

Conclusion

In your own words, explain why using the Arrange - Act - Assert pattern improves test maintainability.

Write a sentence or two on a note and share it with the group.