BDD in go

account.feature

Feature: bank account
  A user's bank account must be able to withdraw and deposit cash

  Scenario Outline: Deposit
    Given I have a bank account with <start>$
    When I deposit <deposit>$
    Then it should have a balance of <end>$
    
    Examples:
      | start | deposit | end |
      | 10    | 0       | 10  |
      | 10    | 10      | 20  |
      | 100   | 50      | 150 |

  Scenario Outline: Withdrawal
    Given I have a bank account with <start>$
    When I withdraw <withdrawal>$
    Then it should have a balance of <end>$

    Examples:
      | start | withdrawal | end |
      | 10    | 0          | 10  |
      | 20    | 10         | 10  |
      | 100   | 50         | 50  |

account.go

package bank

import (
  "flag"
  "fmt"
  "os"
  "testing"

  "github.com/DATA-DOG/godog"
)
var opt = godog.Options{
	Format: "progress",
}

func init() {
  godog.BindFlags("godog.", flag.CommandLine, &opt)
}

func TestMain(m *testing.M) {
	flag.Parse()
	opt.Paths = flag.Args()

	status := godog.RunWithOptions("godogs", func(s *godog.Suite) {
		FeatureContext(s)
	}, opt)

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

var testAccount *account

func iHaveABankAccountWith(balance int) error {
  testAccount = &account{balance:balance}
  return nil
}

func iDeposit(amount int) error {
  testAccount.deposit(amount)
  return nil
}

func iWithdraw(amount int) error {
  testAccount.withdraw(amount)
  return nil
}

func itShouldHaveABalanceOf(balance int) error {
  if testAccount.balance == balance {
    return nil
  }
  return fmt.Errorf("Incorrect account balance")
}

func FeatureContext(s *godog.Suite) {
  s.Step(`^I have a bank account with (\d+)\$$`, iHaveABankAccountWith)
  s.Step(`^I deposit (\d+)\$$`, iDeposit)
  s.Step(`^I withdraw (\d+)\$$`, iWithdraw)
  s.Step(`^it should have a balance of (\d+)\$$`, itShouldHaveABalanceOf)

  s.BeforeScenario(func(interface{}) {
    testAccount = nil
  })
}

account_test.go

package bank

import (
  "flag"
  "fmt"
  "os"
  "testing"

  "github.com/DATA-DOG/godog"
)
var opt = godog.Options{
	Format: "progress",
}

func init() {
  godog.BindFlags("godog.", flag.CommandLine, &opt)
}

func TestMain(m *testing.M) {
	flag.Parse()
	opt.Paths = flag.Args()

	status := godog.RunWithOptions("godogs", func(s *godog.Suite) {
		FeatureContext(s)
	}, opt)

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

var testAccount *account

func iHaveABankAccountWith(balance int) error {
  testAccount = &account{balance:balance}
  return nil
}

func iDeposit(amount int) error {
  testAccount.deposit(amount)
  return nil
}

func iWithdraw(amount int) error {
  testAccount.withdraw(amount)
  return nil
}

func itShouldHaveABalanceOf(balance int) error {
  if testAccount.balance == balance {
    return nil
  }
  return fmt.Errorf("Incorrect account balance")
}

func FeatureContext(s *godog.Suite) {
  s.Step(`^I have a bank account with (\d+)\$$`, iHaveABankAccountWith)
  s.Step(`^I deposit (\d+)\$$`, iDeposit)
  s.Step(`^I withdraw (\d+)\$$`, iWithdraw)
  s.Step(`^it should have a balance of (\d+)\$$`, itShouldHaveABalanceOf)

  s.BeforeScenario(func(interface{}) {
    testAccount = nil
  })
}

go.mod

module bank

require github.com/DATA-DOG/godog v0.7.10

go.sum

github.com/DATA-DOG/godog v0.7.10 h1:BRaQdCOsFth//Ep/J6gtb3xOeDh+sAVjL44ZdK1E9aI=
github.com/DATA-DOG/godog v0.7.10/go.mod h1:z2OZ6a3X0/YAKVqLfVzYBwFt3j6uSt3Xrqa7XTtcQE0=

My version with negative values & the latest GoDog version: https://gist.github.com/davidaparicio/9fa9e664b6eed47e054ee6de426abe1a :)