Merge pull request #364 from cucumber/allow_empty_return_step

feat(step_definition): Allows to define step function without return.

CHANGELOG.md

@@ -12,6 +12,8 @@ This document is formatted according to the principles of [Keep A CHANGELOG](htt
 
 ### Added
 
+* Support for step definitions without return ([364](https://github.com/cucumber/godog/pull/364) -[titouanfreville])
+
 ### Changed
 
 * Upgraded gherkin-go to v19 ([402](https://github.com/cucumber/godog/pull/402) - [mbow])

README.md

@@ -210,6 +210,14 @@ Feature: eat godogs
 
 You may change **return godog.ErrPending** to **return nil** in the three step definitions and the scenario will pass successfully.
 
+Also, you may omit error return if your step does not fail.
+
+```go
+func iEat(arg1 int) {
+	// Eat arg1.
+}
+```
+
 #### Step 5 - Create the main program to test
 
 We only need a number of **godogs** for now. Lets keep it simple.

features/tags.feature

@@ -10,6 +10,7 @@ Feature: tag filters
 
         Background:
           Given passing step
+          And passing step without return
 
         Scenario Outline: parse a scenario
           Given a feature path "<path>"

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/cucumber/messages-go/v16 v16.0.1
 	github.com/hashicorp/go-memdb v1.3.0
 	github.com/hashicorp/go-uuid v1.0.2 // indirect
+	github.com/smartystreets/goconvey v1.6.4
 	github.com/spf13/cobra v1.1.1
 	github.com/spf13/pflag v1.0.5
 	github.com/stretchr/testify v1.7.0

go.sum

@@ -71,6 +71,7 @@ github.com/google/pprof v0.0.0-20190515194954-54271f7e092f/go.mod h1:zfwlbNMJ+OI
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
 github.com/googleapis/gax-go/v2 v2.0.4/go.mod h1:0Wqv26UfaUD9n4G6kQubkQ+KchISgw+vpHVxEJEs9eg=
 github.com/googleapis/gax-go/v2 v2.0.5/go.mod h1:DWXyrwAJ9X0FpwwEdw+IPEYBICEFu5mhpdKc/us6bOk=
+github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1 h1:EGx4pi6eqNxGaHF6qqu48+N2wcFQ5qg5FXgOdqsJ5d8=
 github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
 github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/grpc-ecosystem/go-grpc-middleware v1.0.0/go.mod h1:FiyG127CGDf3tlThmgyCl78X/SZQqEOJBCDaAfeWzPs=
@@ -109,6 +110,7 @@ github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANyt
 github.com/jonboulle/clockwork v0.1.0/go.mod h1:Ii8DK3G1RaLaWxj9trq07+26W01tbo22gdxWY5EU2bo=
 github.com/json-iterator/go v1.1.6/go.mod h1:+SdeFBvtyEkXs7REEP0seUULqWtbJapLOCVDaaPEHmU=
 github.com/jstemmer/go-junit-report v0.0.0-20190106144839-af01ea7f8024/go.mod h1:6v2b51hI/fHJwM22ozAgKL4VKDeJcHhJFhtBdhmNjmU=
+github.com/jtolds/gls v4.20.0+incompatible h1:xdiiI2gbIgH/gLH7ADydsJ1uDOEzR8yvV7C0MuV77Wo=
 github.com/jtolds/gls v4.20.0+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
 github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
 github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvWXihfKN4Q=
@@ -161,7 +163,9 @@ github.com/ryanuber/columnize v0.0.0-20160712163229-9b3edd62028f/go.mod h1:sm1tb
 github.com/sean-/seed v0.0.0-20170313163322-e2103e2c3529/go.mod h1:DxrIzT+xaE7yg65j358z/aeFdxmN0P9QXhEzd20vsDc=
 github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
 github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
+github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d h1:zE9ykElWQ6/NYmHa3jpm/yHnI4xSofP+UP6SpjHcSeM=
 github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=
+github.com/smartystreets/goconvey v1.6.4 h1:fv0U8FUIMPNf1L9lnHLvLhgicrIVChEkdzIKYqbNC9s=
 github.com/smartystreets/goconvey v1.6.4/go.mod h1:syvi0/a8iFYH4r/RixwvyeAJjdLS9QV7WQ/tjFTllLA=
 github.com/soheilhy/cmux v0.1.4/go.mod h1:IM3LyeVVIOuxMH7sFAkER9+bJ4dT7Ms6E4xg4kGIyLM=
 github.com/spaolacci/murmur3 v0.0.0-20180118202830-f09979ecbc72/go.mod h1:JwIasOWyU6f++ZhiEuf87xNszmSA2myDM2Kzu9HwQUA=

internal/models/stepdef.go

@@ -1,6 +1,7 @@
 package models
 
 import (
+	"errors"
 	"fmt"
 	"reflect"
 	"strconv"
@@ -12,6 +13,13 @@ import (
 
 var typeOfBytes = reflect.TypeOf([]byte(nil))
 
+// matchable errors
+var (
+	ErrUnmatchedStepArgumentNumber = errors.New("func received more arguments than expected")
+	ErrCannotConvert               = errors.New("cannot convert argument")
+	ErrUnsupportedArgumentType     = errors.New("unsupported argument type")
+)
+
 // StepDefinition ...
 type StepDefinition struct {
 	formatters.StepDefinition
@@ -28,8 +36,9 @@ type StepDefinition struct {
 func (sd *StepDefinition) Run() interface{} {
 	typ := sd.HandlerValue.Type()
 	if len(sd.Args) < typ.NumIn() {
-		return fmt.Errorf("func expects %d arguments, which is more than %d matched from step", typ.NumIn(), len(sd.Args))
+		return fmt.Errorf("%w: expected %d arguments, matched %d from step", ErrUnmatchedStepArgumentNumber, typ.NumIn(), len(sd.Args))
 	}
+
 	var values []reflect.Value
 	for i := 0; i < typ.NumIn(); i++ {
 		param := typ.In(i)
@@ -41,7 +50,7 @@ func (sd *StepDefinition) Run() interface{} {
 			}
 			v, err := strconv.ParseInt(s, 10, 0)
 			if err != nil {
-				return fmt.Errorf(`cannot convert argument %d: "%s" to int: %s`, i, s, err)
+				return fmt.Errorf(`%w %d: "%s" to int: %s`, ErrCannotConvert, i, s, err)
 			}
 			values = append(values, reflect.ValueOf(int(v)))
 		case reflect.Int64:
@@ -51,17 +60,17 @@ func (sd *StepDefinition) Run() interface{} {
 			}
 			v, err := strconv.ParseInt(s, 10, 64)
 			if err != nil {
-				return fmt.Errorf(`cannot convert argument %d: "%s" to int64: %s`, i, s, err)
+				return fmt.Errorf(`%w %d: "%s" to int64: %s`, ErrCannotConvert, i, s, err)
 			}
-			values = append(values, reflect.ValueOf(int64(v)))
+			values = append(values, reflect.ValueOf(v))
 		case reflect.Int32:
 			s, err := sd.shouldBeString(i)
 			if err != nil {
 				return err
 			}
 			v, err := strconv.ParseInt(s, 10, 32)
 			if err != nil {
-				return fmt.Errorf(`cannot convert argument %d: "%s" to int32: %s`, i, s, err)
+				return fmt.Errorf(`%w %d: "%s" to int32: %s`, ErrCannotConvert, i, s, err)
 			}
 			values = append(values, reflect.ValueOf(int32(v)))
 		case reflect.Int16:
@@ -71,7 +80,7 @@ func (sd *StepDefinition) Run() interface{} {
 			}
 			v, err := strconv.ParseInt(s, 10, 16)
 			if err != nil {
-				return fmt.Errorf(`cannot convert argument %d: "%s" to int16: %s`, i, s, err)
+				return fmt.Errorf(`%w %d: "%s" to int16: %s`, ErrCannotConvert, i, s, err)
 			}
 			values = append(values, reflect.ValueOf(int16(v)))
 		case reflect.Int8:
@@ -81,7 +90,7 @@ func (sd *StepDefinition) Run() interface{} {
 			}
 			v, err := strconv.ParseInt(s, 10, 8)
 			if err != nil {
-				return fmt.Errorf(`cannot convert argument %d: "%s" to int8: %s`, i, s, err)
+				return fmt.Errorf(`%w %d: "%s" to int8: %s`, ErrCannotConvert, i, s, err)
 			}
 			values = append(values, reflect.ValueOf(int8(v)))
 		case reflect.String:
@@ -97,7 +106,7 @@ func (sd *StepDefinition) Run() interface{} {
 			}
 			v, err := strconv.ParseFloat(s, 64)
 			if err != nil {
-				return fmt.Errorf(`cannot convert argument %d: "%s" to float64: %s`, i, s, err)
+				return fmt.Errorf(`%w %d: "%s" to float64: %s`, ErrCannotConvert, i, s, err)
 			}
 			values = append(values, reflect.ValueOf(v))
 		case reflect.Float32:
@@ -107,7 +116,7 @@ func (sd *StepDefinition) Run() interface{} {
 			}
 			v, err := strconv.ParseFloat(s, 32)
 			if err != nil {
-				return fmt.Errorf(`cannot convert argument %d: "%s" to float32: %s`, i, s, err)
+				return fmt.Errorf(`%w %d: "%s" to float32: %s`, ErrCannotConvert, i, s, err)
 			}
 			values = append(values, reflect.ValueOf(float32(v)))
 		case reflect.Ptr:
@@ -124,7 +133,7 @@ func (sd *StepDefinition) Run() interface{} {
 					break
 				}
 
-				return fmt.Errorf(`cannot convert argument %d: "%v" of type "%T" to *messages.PickleStepArgument_PickleDocString`, i, arg, arg)
+				return fmt.Errorf(`%w %d: "%v" of type "%T" to *messages.PickleDocString`, ErrCannotConvert, i, arg, arg)
 			case "messages.PickleTable":
 				if v, ok := arg.(*messages.PickleStepArgument); ok {
 					values = append(values, reflect.ValueOf(v.DataTable))
@@ -136,9 +145,9 @@ func (sd *StepDefinition) Run() interface{} {
 					break
 				}
 
-				return fmt.Errorf(`cannot convert argument %d: "%v" of type "%T" to *messages.PickleStepArgument_PickleTable`, i, arg, arg)
+				return fmt.Errorf(`%w %d: "%v" of type "%T" to *messages.PickleStepArgument_PickleTable`, ErrCannotConvert, i, arg, arg)
 			default:
-				return fmt.Errorf("the argument %d type %T is not supported %s", i, arg, param.Elem().String())
+				return fmt.Errorf("%w: the argument %d type %T is not supported %s", ErrUnsupportedArgumentType, i, arg, param.Elem().String())
 			}
 		case reflect.Slice:
 			switch param {
@@ -149,14 +158,19 @@ func (sd *StepDefinition) Run() interface{} {
 				}
 				values = append(values, reflect.ValueOf([]byte(s)))
 			default:
-				return fmt.Errorf("the slice argument %d type %s is not supported", i, param.Kind())
+				return fmt.Errorf("%w: the slice argument %d type %s is not supported", ErrUnsupportedArgumentType, i, param.Kind())
 			}
 		default:
-			return fmt.Errorf("the argument %d type %s is not supported", i, param.Kind())
+			return fmt.Errorf("%w: the argument %d type %s is not supported", ErrUnsupportedArgumentType, i, param.Kind())
 		}
 	}
 
-	return sd.HandlerValue.Call(values)[0].Interface()
+	res := sd.HandlerValue.Call(values)
+	if len(res) == 0 {
+		return nil
+	}
+
+	return res[0].Interface()
 }
 
 func (sd *StepDefinition) shouldBeString(idx int) (string, error) {
@@ -166,13 +180,13 @@ func (sd *StepDefinition) shouldBeString(idx int) (string, error) {
 		return arg, nil
 	case *messages.PickleStepArgument:
 		if arg.DocString == nil {
-			return "", fmt.Errorf(`cannot convert DocString is not set`)
+			return "", fmt.Errorf(`%w %d: "%v" of type "%T": DocString is not set`, ErrCannotConvert, idx, arg, arg)
 		}
 		return arg.DocString.Content, nil
 	case *messages.PickleDocString:
 		return arg.Content, nil
 	default:
-		return "", fmt.Errorf(`cannot convert argument %d: "%v" of type "%T" to string`, idx, arg, arg)
+		return "", fmt.Errorf(`%w %d: "%v" of type "%T" to string`, ErrCannotConvert, idx, arg, arg)
 	}
 }