Godog

The API is likely to change a few times before we reach 1.0.0

Godog is an open source behavior-driven development framework for go programming language. What is behavior-driven development, you ask? It’s the idea that you start by writing human-readable sentences that describe a feature of your application and how it should work, and only then implement this behavior in software.

The project is inspired by behat and cucumber and is based on cucumber gherkin3 parser.

Godog does not intervene with the standard go test command and it's behavior. You can leverage both frameworks to functionally test your application while maintaining all test related source code in _test.go files.

Godog acts similar compared to go test command. It builds all package sources to a single main package file and replaces main func with it's own and runs the build to test described application behavior in feature files. Production builds remain clean without any test related source code.

Install

go get github.com/DATA-DOG/godog/cmd/godog

Example

The following example can be found here.

Step 1

Imagine we have a godog cart to serve godogs for dinner. At first, we describe our feature in plain text:

# file: examples/godogs/godog.feature
Feature: eat godogs
  In order to be happy
  As a hungry gopher
  I need to be able to eat godogs

  Scenario: Eat 5 out of 12
    Given there are 12 godogs
    When I eat 5
    Then there should be 7 remaining

As a developer, your work is done as soon as you’ve made the program behave as described in the Scenario.

Step 2

If you run godog godog.feature inside the examples/godogs directory. You should see that the steps are undefined:

It gives you undefined step snippets to implement in your test context. You may copy these snippets into your *_test.go file.

Now if you run the tests again. You should see that the definition is now pending. You may change ErrPending to nil and the scenario will pass successfully.

Since we need a working implementation, we may start by implementing only what is necessary.

Step 3

We only need a number of godogs for now. Lets define steps.

/* file: examples/godogs/godog.go */
package main

// Godogs to eat
var Godogs int

func main() { /* usual main func */ }

Step 4

Now lets finish our step implementations in order to test our feature requirements:

/* file: examples/godogs/godog_test.go */
package main

import (
    "fmt"

    "github.com/DATA-DOG/godog"
)

func thereAreGodogs(available int) error {
    Godogs = available
    return nil
}

func iEat(num int) error {
    if Godogs < num {
        return fmt.Errorf("you cannot eat %d godogs, there are %d available", num, Godogs)
    }
    Godogs -= num
    return nil
}

func thereShouldBeRemaining(remaining int) error {
    if Godogs != remaining {
        return fmt.Errorf("expected %d godogs to be remaining, but there is %d", remaining, Godogs)
    }
    return nil
}

func featureContext(s *godog.Suite) {
    s.Step(`^there are (\d+) godogs$`, thereAreGodogs)
    s.Step(`^I eat (\d+)$`, iEat)
    s.Step(`^there should be (\d+) remaining$`, thereShouldBeRemaining)

    s.BeforeScenario(func(interface{}) {
        Godogs = 0 // clean the state before every scenario
    })
}

Now when you run the godog godog.feature again, you should see:

Note: we have hooked to BeforeScenario event in order to reset state. You may hook into more events, like AfterStep to test against an error and print more details about the error or state before failure. Or BeforeSuite to prepare a database.

Documentation

See godoc for general API details. See .travis.yml for supported go versions. See godog -h for general command options.

See implementation examples:

• rest API server
• godogs

Changes

2015-07-03

• changed godog.Suite from interface to struct. Context registration should be updated accordingly. The reason for change: since it exports the same methods and there is no need to mock a function in tests, there is no obvious reason to keep an interface.
• in order to support running suite concurrently, needed to refactor an entry point of application. The Run method now is a func of godog package which initializes and run the suite (or more suites). Method New is removed. This change made godog a little cleaner.
• renamed RegisterFormatter func to Format to be more consistent.

FAQ

Q: Where can I configure common options globally? A: You can't. Alias your common or project based commands: alias godog-wip="godog --format=progress --tags=@wip"

Contributions

Feel free to open a pull request. Note, if you wish to contribute an extension to public (exported methods or types) - please open an issue before to discuss whether these changes can be accepted. All backward incompatible changes are and will be treated cautiously.

License

All package dependencies are MIT or BSD licensed.

Godog is licensed under the three clause BSD license