janivihervas/cupaloy

Simple Go snapshot testing

Incredibly simple Go snapshot testing: cupaloy takes a snapshot of your test output and compares it to a snapshot committed alongside your tests. If the values don't match then you'll be forced to update the snapshot file before the test passes.

Snapshot files are handled automagically: just use the cupaloy.SnapshotT(t, value) function in your tests and cupaloy will automatically find the relevant snapshot file and compare it with the given value.

Usage

func TestExample(t *testing.T) {
    result := someFunction()

    // check that the result is the same as the last time the snapshot was updated
    // if the result has changed then the test will be failed with an error containing
    // a diff of the changes
    cupaloy.SnapshotT(t, result)
}

To update the snapshots simply set the UPDATE_SNAPSHOTS environment variable and run your tests e.g.

UPDATE_SNAPSHOTS=true go test ./...

Installation

go get -u github.com/bradleyjkemp/cupaloy

Further Examples

Table driven tests

var testCases = map[string][]string{
    "TestCaseOne": []string{......},
    "AnotherTestCase": []string{......},
    ....
}

func TestCases(t *testing.T) {
    for testName, args := range testCases {
        t.Run(testName, func(t *testing.T) {
            result := functionUnderTest(args...)
            cupaloy.SnapshotT(t, result)
        })
    }
}

Changing output directory

func TestSubdirectory(t *testing.T) {
    result := someFunction()
    snapshotter := cupaloy.New(cupaloy.SnapshotSubdirectory("testdata"))
    err := snapshotter.Snapshot(result)
    if err != nil {
        t.Fatalf("error: %s", err)
    }
}

For further usage examples see basic_test.go and advanced_test.go in the examples/ directory which are both kept up to date and run on CI.