godog

Godog

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

Package godog is the official Cucumber BDD framework for Golang, it merges specification and test documentation into one cohesive whole. The author is a core member of cucumber team.

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 its 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 uses go compiler and linker tool in order to produce test executable. Godog contexts needs to be exported same as Test functions for go test.

Godog ships gherkin parser dependency as a subpackage. This will ensure that it is always compatible with the installed version of godog. So in general there are no vendor dependencies needed for installation.

The following about section was taken from cucumber homepage.

About

A single source of truth

Cucumber merges specification and test documentation into one cohesive whole.

Living documentation

Because they're automatically tested by Cucumber, your specifications are always bang up-to-date.

Focus on the customer

Business and IT don't always understand each other. Cucumber's executable specifications encourage closer collaboration, helping teams keep the business goal in mind at all times.

Less rework

When automated testing is this much fun, teams can easily protect themselves from costly regressions.

Install

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

Example

The following example can be found here.

Step 1

Given we create a new go package $GOPATH/src/godogs. From now on, this is our work directory cd $GOPATH/src/godogs.

Imagine we have a godog cart to serve godogs for lunch. First of all, we describe our feature in plain text - vim $GOPATH/src/godogs/features/godogs.feature:

# file: $GOPATH/src/godogs/features/godogs.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.

NOTE: same as go test godog respects package level isolation. All your step definitions should be in your tested package root directory. In this case - $GOPATH/src/godogs

Step 2

If godog is installed in your GOPATH. We can run godog inside the $GOPATH/src/godogs directory. You should see that the steps are undefined:

If we wish to vendor godog dependency, we can do it as usual, using tools you prefer:

git clone https://github.com/DATA-DOG/godog.git $GOPATH/src/godogs/vendor/github.com/DATA-DOG/godog

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

Our directory structure should now look like:

If you copy the snippets into our test file and run godog again. We should see the step 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 keep it simple.

/* file: $GOPATH/src/godogs/godogs.go */
package main

// Godogs available to eat
var Godogs int

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

Step 4

Now lets implement our step definitions, which we can copy from generated console output snippets in order to test our feature requirements:

/* file: $GOPATH/src/godogs/godogs_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 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.

Running Godog with go test

There was a question asked whether it is possible to run godog from go test command. And the answer is yes. You can run it using go TestMain func available since go 1.4. In this case it is not necessary to have godog command installed. See the following example:

/* file: $GOPATH/src/godogs/godogs_test.go */
package main

import (
	"flag"
	"os"
	"testing"

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

func TestMain(m *testing.M) {
	args := os.Args
	// args for godog
	os.Args = []string{
		args[0],
		"-f", "progress",
		"features",
	}

	status := godog.Run(func(s *godog.Suite) {
		FeatureContext(s)
	})

	os.Args = args
	flag.Parse()

	if st := m.Run(); st > status {
		status = st
	}
	os.Exit(status)
}

References and Tutorials

• how to use godog by semaphoreci

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
• rest API with Database
• godogs

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