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

Issue: It is not possible to use function without return when
       matching steps, resulting in a lot of Nil only error
       returns.

Fix: Allows to provide empty result function by correctly matching
     reflect Calls on step Handler.
     When nothing is returned by the Handler, it will return
     nil as if errors was nil.

internal/models/stepdef.go

@@ -156,7 +156,11 @@ func (sd *StepDefinition) Run() interface{} {
  }
  }
 
- 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) {

suite_context_test.go

@@ -413,9 +413,8 @@ func (tc *godogFeaturesScenario) aFeatureFile(path string, body *DocString) erro
  return err
 }
 
-func (tc *godogFeaturesScenario) featurePath(path string) error {
+func (tc *godogFeaturesScenario) featurePath(path string) {
  tc.paths = append(tc.paths, path)
- return nil
 }
 
 func (tc *godogFeaturesScenario) parseFeatures() error {

test_context.go

@@ -176,8 +176,8 @@ func (ctx *ScenarioContext) Step(expr, stepFunc interface{}) {
  panic(fmt.Sprintf("expected handler to be func, but got: %T", stepFunc))
  }
 
- if typ.NumOut() != 1 {
- panic(fmt.Sprintf("expected handler to return only one value, but it has: %d", typ.NumOut()))
+ if typ.NumOut() > 1 {
+ panic(fmt.Sprintf("expected handler to return either zero or one value, but it has: %d", typ.NumOut()))
  }
 
  def := &models.StepDefinition{
@@ -188,19 +188,21 @@ func (ctx *ScenarioContext) Step(expr, stepFunc interface{}) {
  HandlerValue: v,
  }
 
- typ = typ.Out(0)
- switch typ.Kind() {
- case reflect.Interface:
- if !typ.Implements(errorInterface) {
- panic(fmt.Sprintf("expected handler to return an error, but got: %s", typ.Kind()))
+ if typ.NumOut() == 1 {
+ typ = typ.Out(0)
+ switch typ.Kind() {
+ case reflect.Interface:
+ if !typ.Implements(errorInterface) {
+ panic(fmt.Sprintf("expected handler to return an error, but got: %s", typ.Kind()))
+ }
+ case reflect.Slice:
+ if typ.Elem().Kind() != reflect.String {
+ panic(fmt.Sprintf("expected handler to return []string for multistep, but got: []%s", typ.Kind()))
+ }
+ def.Nested = true
+ default:
+ panic(fmt.Sprintf("expected handler to return an error or []string, but got: %s", typ.Kind()))
  }
- case reflect.Slice:
- if typ.Elem().Kind() != reflect.String {
- panic(fmt.Sprintf("expected handler to return []string for multistep, but got: []%s", typ.Kind()))
- }
- def.Nested = true
- default:
- panic(fmt.Sprintf("expected handler to return an error or []string, but got: %s", typ.Kind()))
  }
 
  ctx.suite.steps = append(ctx.suite.steps, def)