Oftentimes, tests are about comparing an instance of datastructure to an expected one. However, it might quickly become a lot of work to update those expectations when modifying the code. Like the butterfly effect, one tiny change to one line of code might have big consequences on the outcome of the algorithm and can therefore impact a lot of tests.
Golden files are files containing a serialized version of the expected instance of the datastructure that is used by the test as the expectation for the outcome of th 6463 e algorithm. This repository offer primitives for creating and maintaining golden files, also called goldens.
go get github.com/clems4ever/go-testgoldentype MyStruct struct {
ID int
Title string
Content string
}
func TestExample(t *testing.T) {
s := MyStruct{
ID: 1,
Title: "this is a title",
Content: "Here is a little story",
}
// Generate a path of a file to be stored in the test directory dedicated to this specific test.
goldenPath := testgolden.GetTestDataFilePath(t, "golden.json")
// If the env variable CI=1 is not set, the golden is updated with the latest version of the struct,
// but if the variable is set, the CI will check that the golden and the actual data is equal.
testgolden.RequireDataEqualToJSON(t, goldenPath, s)
}