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Golden file testing for Go
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goldie - Golden test utility for Go

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goldie is a golden file test utility for Go projects. It's typically used for testing responses with larger data bodies.

The concept is straight forward. Valid response data is stored in a "golden file". The actual response data will be byte compared with the golden file and the test will fail if there is a difference.

Updating the golden file can be done by running go test -update ./....

See the GoDoc for API reference and configuration options.

Installation

Install the latest version, v2, with:

go get -u github.com/sebdah/goldie/v2

For the older v1 release, please use:

go get -u github.com/sebdah/goldie

Example usage

Basic assertions

The below example fetches data from a REST API. The last line in the test is the actual usage of goldie. It takes the HTTP response body and asserts that it's what is present in the golden test file.

func TestExample(t *testing.T) {
    recorder := httptest.NewRecorder()

    req, err := http.NewRequest("GET", "/example", nil)
    assert.Nil(t, err)

    handler := http.HandlerFunc(ExampleHandler)
    handler.ServeHTTP()

    g := goldie.New(t)
    g.Assert(t, "example", recorder.Body.Bytes())
}

Assertions using templates

If some values in the golden file can change depending on the test, you can use golang template in the golden file and pass the data to AssertWithTemplate.

example.golden

This is a {{ .Type }} file.

Test

func TestTemplateExample(t *testing.T) {
    recorder := httptest.NewRecorder()

    req, err := http.NewRequest("POST", "/example/Golden", nil)
    assert.Nil(t, err)

    handler := http.HandlerFunc(ExampleHandler)
    handler.ServeHTTP()

    data := struct {
        Type	string
    }{
        Type:	"Golden",
    }

    g := goldie.New(t)
    g.AssertWithTemplate(t, "example", data, recorder.Body.Bytes())
}

Then run your test with the -update flag the first time to store the result.

go test -update ./...

For any consecutive runs where you actually want to compare the data, simply drop the -update flag.

go test ./...

Flags

Clean output directory

Using -update along with -clean flag will clear the fixture directory before updating golden files.

go test -update -clean ./...

Options

goldie supports a number of configuration options that will alter the behavior of the library. These options should be passed into the goldie.New() method.

func TestNewExample(t *testing.T) {
    g := goldie.New(
        t,
        goldie.WithFixtureDir("test-fixtures"),
        goldie.WithNameSuffix(".golden.json"),
        goldie.WithDiffEngine(goldie.ColoredDiff),
        goldie.WithTestNameForDir(true),
    )

    g.Assert(t, "example", []byte("my example data"))
}

Available options

Option Comment Default
WithFixtureDir Set fixture dir name testdata
WithNameSuffix Suffix for fixture files. .golden
WithDirPerms Directory permissions for fixtures 0755
WithFilePerms File permissions for fixtures 0644
WithDiffEngine Diff engine to use for diff output ClassicDiff
WithDiffFn Custom diff logic to be used None
WithIgnoreTemplateErrors Ignore errors from templates false
WithTestNameForDir Create a folder with the tests name for the fixtures false
WithSubTestNameForDir Create a folder with the sub tests name for the fixtures false

Diff output

Goldie has three output modes; classic diff (default), colored diffs and simple mode.

You can select your preferred output using the WithDiffEngine option:

g.New(
    t,
    goldie.WithDiffEngine(goldie.ColoredDiff), // Simple, ColoredDiff, ClassicDiff
)

Goldie v2

With the release of Goldie v2.0.0 we are introducing features that will break backwards compatibility with older versions of the test helper. A few things have changed:

New default fixture directory

There is a new default directory for fixtures, testdata. This directory is a better default as it is more widely used in the Go community (including the standard library). See issue #10 for details.

New way to initialize Goldie

With the introduction of the functional options we also introduced goldie.New, which is initializing Goldie. Assert* and other methods are now accessed like:

g := goldie.New(t)
g.Assert(t, ...)

FAQ

Do you need any help in the project?

Yes, please! Pull requests are most welcome. On the wish list:

  • Unit tests.

Why the name goldie?

The name comes from the fact that it's for Go and handles golden file testing. But yes, it may not be the best name in the world.

How did you come up with the idea?

This is based on the great Advanced Go testing talk by @mitchellh.

License

MIT

Copyright 2016 Sebastian Dahlgren sebastian.dahlgren@gmail.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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