add support for binding godog flags to specified *flag.FlagSet

allows to run with go test and use all godog flags for filtering
related to #120

README.md

@@ -237,6 +237,42 @@ run it using go [TestMain](https://golang.org/pkg/testing/#hdr-Main) func
 available since **go 1.4**. In this case it is not necessary to have
 **godog** command installed. See the following example:
 
+The following example binds **godog** flags with specified prefix `godog`
+in order to prevent flag collisions.
+
+``` go
+var opt = godog.Options{Output: colors.Colored(os.Stdout)}
+
+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)
+}
+```
+
+Then you may run tests with by specifying flags in order to filter
+features.
+
+```
+go test -v --godog.format=progress --godog.random --godog.tags=wip
+go test -v --godog.format=pretty --godog.random -race -coverprofile=coverage.txt -covermode=atomic
+```
+
+The following example does not bind godog flags, instead manually
+configuring needed options.
+
 ``` go
 func TestMain(m *testing.M) {
 	status := godog.RunWithOptions("godog", func(s *godog.Suite) {
@@ -251,8 +287,7 @@ func TestMain(m *testing.M) {
 		status = st
 	}
 	os.Exit(status)
-}
+} ```
-```
 
 You can even go one step further and reuse **go test** flags, like
 **verbose** mode in order to switch godog **format**. See the following

examples/godogs/godogs_test.go

@@ -2,22 +2,28 @@
 package main
 
 import (
+	"flag"
 	"fmt"
 	"os"
 	"testing"
-	"time"
 
 	"github.com/DATA-DOG/godog"
+	"github.com/DATA-DOG/godog/colors"
 )
 
+var opt = godog.Options{Output: colors.Colored(os.Stdout)}
+
+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)
-	}, godog.Options{
+	}, opt)
-		Format:    "progress",
-		Paths:     []string{"features"},
-		Randomize: time.Now().UTC().UnixNano(), // randomize scenario execution order
-	})
 
 	if st := m.Run(); st > status {
 		status = st

flags.go

@@ -34,7 +34,17 @@ var descRandomOption = "Randomly shuffle the scenario execution order.\n" +
 	s(4) + `e.g. ` + colors.Yellow(`--random`) + " or " + colors.Yellow(`--random=5738`)
 
 // FlagSet allows to manage flags by external suite runner
+// builds flag.FlagSet with godog flags binded
 func FlagSet(opt *Options) *flag.FlagSet {
+	set := flag.NewFlagSet("godog", flag.ExitOnError)
+	BindFlags("", set, opt)
+	set.Usage = usage(set, opt.Output)
+	return set
+}
+
+// BindFlags binds godog flags to given flag set prefixed
+// by given prefix, without overriding usage
+func BindFlags(prefix string, set *flag.FlagSet, opt *Options) {
 	descFormatOption := "How to format tests output. Built-in formats:\n"
 	// @TODO: sort by name
 	for name, desc := range AvailableFormatters() {
@@ -42,21 +52,18 @@ func FlagSet(opt *Options) *flag.FlagSet {
 	}
 	descFormatOption = strings.TrimSpace(descFormatOption)
 
-	set := flag.NewFlagSet("godog", flag.ExitOnError)
+	set.StringVar(&opt.Format, prefix+"format", "pretty", descFormatOption)
-	set.StringVar(&opt.Format, "format", "pretty", descFormatOption)
+	set.StringVar(&opt.Format, prefix+"f", "pretty", descFormatOption)
-	set.StringVar(&opt.Format, "f", "pretty", descFormatOption)
+	set.StringVar(&opt.Tags, prefix+"tags", "", descTagsOption)
-	set.StringVar(&opt.Tags, "tags", "", descTagsOption)
+	set.StringVar(&opt.Tags, prefix+"t", "", descTagsOption)
-	set.StringVar(&opt.Tags, "t", "", descTagsOption)
+	set.IntVar(&opt.Concurrency, prefix+"concurrency", 1, descConcurrencyOption)
-	set.IntVar(&opt.Concurrency, "concurrency", 1, descConcurrencyOption)
+	set.IntVar(&opt.Concurrency, prefix+"c", 1, descConcurrencyOption)
-	set.IntVar(&opt.Concurrency, "c", 1, descConcurrencyOption)
+	set.BoolVar(&opt.ShowStepDefinitions, prefix+"definitions", false, "Print all available step definitions.")
-	set.BoolVar(&opt.ShowStepDefinitions, "definitions", false, "Print all available step definitions.")
+	set.BoolVar(&opt.ShowStepDefinitions, prefix+"d", false, "Print all available step definitions.")
-	set.BoolVar(&opt.ShowStepDefinitions, "d", false, "Print all available step definitions.")
+	set.BoolVar(&opt.StopOnFailure, prefix+"stop-on-failure", false, "Stop processing on first failed scenario.")
-	set.BoolVar(&opt.StopOnFailure, "stop-on-failure", false, "Stop processing on first failed scenario.")
+	set.BoolVar(&opt.Strict, prefix+"strict", false, "Fail suite when there are pending or undefined steps.")
-	set.BoolVar(&opt.Strict, "strict", false, "Fail suite when there are pending or undefined steps.")
+	set.BoolVar(&opt.NoColors, prefix+"no-colors", false, "Disable ansi colors.")
-	set.BoolVar(&opt.NoColors, "no-colors", false, "Disable ansi colors.")
+	set.Var(&randomSeed{&opt.Randomize}, prefix+"random", descRandomOption)
-	set.Var(&randomSeed{&opt.Randomize}, "random", descRandomOption)
-	set.Usage = usage(set, opt.Output)
-	return set
 }
 
 type flagged struct {
@@ -180,7 +187,10 @@ func (rs *randomSeed) Set(s string) error {
 	return err
 }
 
-func (rs randomSeed) String() string {
+func (rs *randomSeed) String() string {
+	if rs.ref == nil {
+		return "0"
+	}
 	return strconv.FormatInt(*rs.ref, 10)
 }
 

godog.go

@@ -39,4 +39,4 @@ Godog was inspired by Behat and Cucumber the above description is taken from it'
 package godog
 
 // Version of package - based on Semantic Versioning 2.0.0 http://semver.org/
-const Version = "v0.7.6"
+const Version = "v0.7.7"