Testing Strategies

Focus on one failing test at a time

If you have a large number of failing tests, the output can get overwhelming. This will slow you down.

Instead, try to focus on one test at a time. Here are specific strategies for doing that:

Backend: Use a command like this to run only one set of backend tests. Here FooControllerTests is the name of the test class (not the unit under test):

mvn test -Dtest=FooControllerTests

You can further limit the run to a single test by using:

mvn test -Dtest=FooControllerTests\#method_name_of_test

You can also limit the tests by commenting out all tests, and uncommenting them one at a time. Each time a test fails, focus on fixing that one until they all pass.

Frontend: You can use this command to focus on tests for one file at a time. In this case, the expression after the -- is treated as a regular expression, so you only need as many characters as are needed to match what you are testing:

npm test -- FooTable

You can further control which tests run by changing code as follows:

Change this	To This	For this result
test(...)	test.only(...)	Only this test will run. If there are multiple tests marked with .only, that set of tests will run
test(...)	test.skip(...)	Skip this test.

You can also apply .only and .skip to entire describe blocks, and to tests marked with it instead of test.

Maybe the test is right and the code is wrong

If you are trying to figure out why a test is not passing, and you are stuck, ask yourself this question:

• Is it possible that the test is right and the code is wrong?

Things to try:

• If this is a frontend test: do you have a storybook entry for the component? If so, try walking through all of the steps of the test in the storybook component. (If you don’t have a storybook entry yet, make one; that process may help you discover what you’ve missed).
• Try actually running the code for real with the full backend and frontend, either on localhost or a dokku deployment. Does the code actually do what it’s supposed to do?