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go

How to run test cases in a specified file?

My package test cases are scattered across multiple files, if I run go test <package_name> it runs all test cases in the package.

It is unnecessary to run all of them though. Is there a way to specify a file for go test to run, so that it only runs test cases defined in the file?

Solution

  • There are two ways. The easy one is to use the -run flag and provide a pattern matching names of the tests you want to run.

    Example:

    $ go test packageName -run NameOfTest

    See the docs for more info.

    Note that the -run flag may also run other tests if they contain the string NameOfTest, as the -run flag matches a regexp.

    So to ensure that only a test named exactly 'NameOfTest' is run, one has to use the regexp ^NameOfTest$:

    $ go test -run "^NameOfTest$"

    The other way is to name the specific file, containing the tests you want to run:

    $ go test foo_test.go

    But there's a catch. This works well if:

    • foo.go is in package foo.
    • foo_test.go is in package foo_test and imports 'foo'.

    If foo_test.go and foo.go are the same package (a common case) then you must name all other files required to build foo_test. In this example it would be:

    $ go test foo_test.go foo.go

    I'd recommend to use the -run pattern. Or, where/when possible, always run all package tests.