Structure unit tests

The AAA patterns provides a simple structure for all tests. It advocates for splitting each test into three parts:

• arrange : bring the SUT (system under test aka the class you are testing) and its dependencies to a desired states
• act : calls the method, pass the prepared dependencies and capture the output value (if any)
• assert : verify the outcome

Once u get used to the uniformity of this pattern, it will help you to easily read and understand any test.

Given-When-Then pattern is similar to AAA pattern, it advocates to break down tests into similar 3 parts:

• Given corresponds to the arrange section
• When corresponds to the act section
• Then corresponds to the assert section

The only distinction is that the Given-When-Then structure is more readable to non-programmers.

Guidelines

• avoid multiple arrange/act/assert sections
• distinguish the SUT in tests by naming it sut
• differentiate the three test sections either by putting Arrange, Act, and Assert comments before them or by introducing empty lines between these sections
• act section is normally a single line code
• avoid if statements in tests