𝗨𝗻𝗶𝘁 𝗧𝗲𝘀𝘁𝗶𝗻𝗴 𝗕𝗲𝘀𝘁 𝗣𝗿𝗮𝗰𝘁𝗶𝗰𝗲𝘀

Unit testing is software testing in which individual units or components of a software application are tested. Unit testing aims to validate that each software unit performs as designed.

Unit tests ensure code quality, ease of maintenance, facilitate refactoring, and increase development speed.

When we talk about best practices, here is a list of that one should follow:

𝟭. 𝗪𝗿𝗶𝘁𝗲 𝗮 𝗻𝗲𝘄 𝘁𝗲𝘀𝘁 𝗳𝗼𝗿 𝗲𝘃𝗲𝗿𝘆 𝗱𝗲𝗳𝗲𝗰𝘁: When you encounter a defect, write a test that exposes the defect. This is also known as regression testing.

𝟮. 𝗞𝗲𝗲𝗽 𝘁𝗲𝘀𝘁𝘀 𝘀𝗺𝗮𝗹𝗹 𝗮𝗻𝗱 𝗳𝗼𝗰𝘂𝘀𝗲𝗱: A unit test should be limited to an individual function or method. This makes it easier to identify and fix problems when the test fails.

𝟯. 𝗜𝘀𝗼𝗹𝗮𝘁𝗲 𝘆𝗼𝘂𝗿 𝘁𝗲𝘀𝘁𝘀: Make sure each test is independent of all the others. This allows you to run each test individually and in any order.

𝟰. 𝗢𝗿𝗴𝗮𝗻𝗶𝘇𝗲 𝘆𝗼𝘂𝗿 𝘁𝗲𝘀𝘁𝘀 𝗯𝘆 𝘁𝗲𝘀𝘁 𝘁𝘆𝗽𝗲: You can organize your tests by the type of object they are testing or the type of test they are. This makes it easier to find and run related tests.

𝟱. 𝗧𝗲𝘀𝘁 𝗼𝗻𝗲 𝗰𝗼𝗱𝗲 𝗽𝗮𝘁𝗵 𝗮𝘁 𝗮 𝘁𝗶𝗺𝗲: Each test should verify one specific code path through a method. This makes it easier to understand what is being tested and why a test might fail.

𝟲. 𝗔𝘃𝗼𝗶𝗱 𝗹𝗼𝗴𝗶𝗰 𝗶𝗻 𝘁𝗲𝘀𝘁𝘀: When you put logic into your tests, you risk introducing bugs into your tests. Keep your tests simple.

𝟳. 𝗔𝘃𝗼𝗶𝗱 𝘀𝘁𝗮𝘁𝗶𝗰 𝗺𝗲𝘁𝗵𝗼𝗱𝘀 𝗶𝗻 𝘆𝗼𝘂𝗿 𝗰𝗹𝗮𝘀𝘀𝗲𝘀 𝘂𝗻𝗱𝗲𝗿 𝘁𝗲𝘀𝘁: Static methods can't be overridden in subclasses, which makes them difficult to test. Avoid using static methods in the classes you are testing.

𝟴. 𝗔𝘃𝗼𝗶𝗱 𝘁𝗲𝘀𝘁𝗶𝗻𝗴 𝗶𝗺𝗽𝗹𝗲𝗺𝗲𝗻𝘁𝗮𝘁𝗶𝗼𝗻 𝗱𝗲𝘁𝗮𝗶𝗹𝘀: Your tests should focus on the behavior of your code, not its implementation. If you test implementation details, your tests can break even if the behavior of your code remains the same.

𝟵. 𝗪𝗿𝗶𝘁𝗲 𝘁𝗲𝘀𝘁𝘀 𝗳𝗼𝗿 𝗺𝗲𝘁𝗵𝗼𝗱𝘀 𝘁𝗵𝗮𝘁 𝗵𝗮𝘃𝗲 𝘁𝗵𝗲 𝗺𝗼𝘀𝘁 𝗶𝗺𝗽𝗮𝗰𝘁 𝗳𝗶𝗿𝘀𝘁: Focus your testing efforts on the methods that impact your application most. This typically includes methods that contain complex logic or interact with external resources.

𝟭𝟬. 𝗨𝘀𝗲 𝘁𝗵𝗲 𝗔𝗔𝗔 𝗽𝗮𝘁𝘁𝗲𝗿𝗻: Arrange, Act, Assert is a typical pattern for writing unit tests. The Arrange section of a unit test method initializes objects and sets the data value passed to the method under test. The Act section invokes the method under test with the arranged parameters. The Assert section verifies that the method under test behaves as expected.