How to run golang tests sequentially?

Question

When I run go test, my output:

--- FAIL: TestGETSearchSuccess (0.00s)         Location:       drivers_api_test.go:283         Error:          Not equal: 200 (expected)                                 != 204 (actual)  --- FAIL: TestGETCOSearchSuccess (0.00s)         Location:       drivers_api_test.go:391         Error:          Not equal: 200 (expected)                                 != 204 (actual) 

But after I run go test again, all my tests pass.

Tests fail only when I reset my mysql database, and then run go test for the first time.

For every GET request, I do a POST request before to ensure that there is data created in the DB.

Could anyone help me with how to make sure that tests are run sequentially? That is the POST requests are run before the GET requests?

Answer 1

You can't / shouldn't rely on test execution order. The order in which tests are executed is not defined, and with the use of testing flags it is possible to exclude tests from running, so you have no guarantee that they will run at all.

For example the following command will only run tests whose name contains a 'W' letter:

go test -run W 

Also note that if some test functions mark themselves eligible for parallel execution using the T.Parallel() method, the go tool will reorder the tests to first run non-parallel tests, and then run parallel tests in parallel under certain circumstances (controlled by test flags like -p). You can see examples of this in this answer: Are tests executed in parallel in Go or one by one?

Tests should be independent from each other. If a test function has prerequisites, that cannot be done/implemented in another test function.

Options to do additional tasks before a test function is run:

• You may put it in the test function itself
• You may put it in a package init() function, in the _test.go file itself. This will run once before execution of test functions begins.
• You may choose to implement a TestMain() function which will be called first and in which you may do additional setup before you call M.Run() to trigger the execution of test functions.
• You may mix the above options.

In your case in package init() or TestMain() you should check if your DB is initialized (there are test records inserted), and if not, insert the test records.

Note that starting with Go 1.7, you may use subtests in which you define execution order of subtests. For details see blog post: Using Subtests and Sub-benchmarks, and the package doc of the testing package.