feat: support auto converting doc strings to plain strings

features/run.feature

@@ -262,3 +262,16 @@ Feature: run features
       another undefined step
       """
     And the suite should have failed
+
+  Scenario: should be able to convert a Doc String to a `*godog.DocString` argument
+    Given call func(*godog.DocString) with:
+    """
+    text
+    """
+
+  Scenario: should be able to convert a Doc String to a `string` argument
+    Given call func(string) with:
+    """
+    text
+    """
+

internal/models/stepdef.go

@@ -161,11 +161,16 @@ func (sd *StepDefinition) Run() interface{} {
 
 func (sd *StepDefinition) shouldBeString(idx int) (string, error) {
 	arg := sd.Args[idx]
-	s, ok := arg.(string)
-	if !ok {
+	switch arg := arg.(type) {
+	case string:
+		return arg, nil
+	case *messages.PickleStepArgument:
+		return arg.GetDocString().Content, nil
+	case *messages.PickleStepArgument_PickleDocString:
+		return arg.Content, nil
+	default:
 		return "", fmt.Errorf(`cannot convert argument %d: "%v" of type "%T" to string`, idx, arg, arg)
 	}
-	return s, nil
 }
 
 // GetInternalStepDefinition ...

internal/models/stepdef_test.go

@@ -1,6 +1,7 @@
 package models_test
 
 import (
+	"fmt"
 	"reflect"
 	"strings"
 	"testing"
@@ -149,3 +150,26 @@ func TestUnexpectedArguments(t *testing.T) {
 	// 	t.Fatalf("expected an error due to wrong argument type, but got none")
 	// }
 }
+
+func TestShouldSupportDocStringToStringConversion(t *testing.T) {
+	fn := func(a string) error {
+		if a != "hello" {
+			return fmt.Errorf("did not get hello")
+		}
+		return nil
+	}
+
+	def := &models.StepDefinition{
+		StepDefinition: formatters.StepDefinition{
+			Handler: fn,
+		},
+		HandlerValue: reflect.ValueOf(fn),
+		Args: []interface{}{&messages.PickleStepArgument_PickleDocString{
+			Content: "hello",
+		}},
+	}
+
+	if err := def.Run(); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}

run_test.go

@@ -413,11 +413,11 @@ func Test_AllFeaturesRun(t *testing.T) {
 ...................................................................... 140
 ...................................................................... 210
 ...................................................................... 280
-..........................                                             306
+............................                                           308
 
 
-79 scenarios (79 passed)
-306 steps (306 passed)
+81 scenarios (81 passed)
+308 steps (308 passed)
 0s
 `
 

suite_context_test.go

@@ -101,6 +101,13 @@ func InitializeScenario(ctx *ScenarioContext) {
 		return nil
 	})
 
+	ctx.Step(`^call func\(\*godog\.DocString\) with:$`, func(arg *DocString) error {
+		return nil
+	})
+	ctx.Step(`^call func\(string\) with:$`, func(arg string) error {
+		return nil
+	})
+
 	ctx.BeforeStep(tc.inject)
 }