feat: output suggestions in the order steps were defined

README.md

@@ -77,22 +77,22 @@ type suite struct {
 When you run the tests, they should fail and suggest that you add these
 step definitions:
 ```go
-func (s *suite) IEat(a int64) {
+func (s *suite) IHaveCukes(a int64) {
     panic("PENDING")
 }
 
-func (s *suite) IHaveLeft(a int64) {
+func (s *suite) IEat(a int64) {
     panic("PENDING")
 }
 
-func (s *suite) IHaveCukes(a int64) {
+func (s *suite) IHaveLeft(a int64) {
     panic("PENDING")
 }
 
 Steps can be manually registered with the runner for customization using this code:
-  Step(`^I\s+have\s+(-?\d+)\s+cukes$`, (*simpleSuite).IHaveCukes).
-  Step(`^I\s+eat\s+(-?\d+)$`, (*simpleSuite).IEat).
-  Step(`^I\s+have\s+(-?\d+)\s+left$`, (*simpleSuite).IHaveLeft)
+  Step(`^I\s+have\s+(-?\d+)\s+cukes$`, (*suite).IHaveCukes).
+  Step(`^I\s+eat\s+(-?\d+)$`, (*suite).IEat).
+  Step(`^I\s+have\s+(-?\d+)\s+left$`, (*suite).IHaveLeft)
 ```
 
 Copy these definitions into `simple_test.go`.

find_step.go

@@ -22,7 +22,10 @@ func (r *Runner) findStep(t *testing.T, step *messages.PickleStep) *stepDef {
 		return r.addStepDef(t, sig.regex, method.Func)
 	}
 
-	r.suggestions[sig.name] = sig
+	if !r.haveSuggestion[sig.name] {
+		r.haveSuggestion[sig.name] = true
+		r.suggestions = append(r.suggestions, sig)
+	}
 	t.Errorf("can't find step definition for: %s", step.Text)
 
 	return nil

runner.go

@@ -17,7 +17,8 @@ type Runner struct {
 	paths                []string
 	parallel             bool
 	stepDefs             []*stepDef
-	suggestions          map[string]methodSig
+	haveSuggestion       map[string]bool
+	suggestions          []methodSig
 	supportedSpecialArgs map[reflect.Type]specialArgGetter
 	suiteInjectors       []*suiteInjector
 	beforeHooks          []*stepDef
@@ -56,10 +57,10 @@ func NewRunner(t *testing.T, suiteType interface{}) *Runner {
 	initGlobalTagExpr()
 
 	r := &Runner{
-		topLevelT:   t,
-		incr:        &messages.Incrementing{},
-		parallel:    false,
-		suggestions: map[string]methodSig{},
+		topLevelT:      t,
+		incr:           &messages.Incrementing{},
+		parallel:       false,
+		haveSuggestion: map[string]bool{},
 		supportedSpecialArgs: map[reflect.Type]specialArgGetter{
 			// TestingT
 			reflect.TypeOf((*TestingT)(nil)).Elem(): func(runner *scenarioRunner) interface{} {