Split RegisterContext to make it more flexible for dependents to just…

… register what is needed

expander.go

@@ -7,6 +7,8 @@ import (
 	"strings"
 )
 
+const varDelimiter = "$"
+
 // ErrUnsupportedExpander indicates that the provided expander is not supported.
 var ErrUnsupportedExpander = errors.New("unsupported expander")
 
@@ -32,7 +34,7 @@ func BeforeScenario(provide func() Pairs) func() Expander {
 }
 
 func placeholder(name string) string {
-	return fmt.Sprintf("$%s", name)
+	return fmt.Sprintf("%s%s", varDelimiter, name)
 }
 
 // runtimeExpander expands variables from a provider.
@@ -74,7 +76,7 @@ func newExpander(e interface{}) Expander {
 	case Pairs:
 		return mapExpander(e)
 
-	case func() map[string]string:
+	case func() Pairs:
 		return runtimeExpander(e)
 
 	case func() Expander:
@@ -92,3 +94,7 @@ func newExpander(e interface{}) Expander {
 
 	panic(fmt.Errorf("%w: got %T", ErrUnsupportedExpander, e))
 }
+
+func doExpand(expand Expander, s string) string {
+	return expand(s)
+}

step.go

@@ -11,8 +11,9 @@ type StepExpander struct {
 	expand    Expander
 }
 
-// RegisterContext register StepExpander to the test suite.
-func (m *StepExpander) RegisterContext(s *godog.ScenarioContext) {
+// RegisterExpander registers only the expander to the test suite to let it work.
+// There will be no registration of step definition in this method.
+func (m *StepExpander) RegisterExpander(s *godog.ScenarioContext) {
 	s.BeforeScenario(func(sc *godog.Scenario) {
 		m.expand = chainExpanders(m.expanders...)
 	})
@@ -22,6 +23,11 @@ func (m *StepExpander) RegisterContext(s *godog.ScenarioContext) {
 	})
 }
 
+// RegisterContext register everything to the test suite.
+func (m *StepExpander) RegisterContext(s *godog.ScenarioContext) {
+	m.RegisterExpander(s)
+}
+
 // NewStepExpander initiates a new variable expanders for cucumber steps.
 func NewStepExpander(expanders ...interface{}) *StepExpander {
 	return &StepExpander{
@@ -35,20 +41,20 @@ func ExpandStep(st *godog.Step, expanders ...interface{}) {
 }
 
 func expandStep(st *godog.Step, expand Expander) {
-	st.Text = expand(st.Text)
+	st.Text = doExpand(expand, st.Text)
 
 	if st.Argument == nil {
 		return
 	}
 
 	switch msg := st.Argument.Message.(type) {
 	case *messages.PickleStepArgument_DocString:
-		msg.DocString.Content = expand(msg.DocString.Content)
+		msg.DocString.Content = doExpand(expand, msg.DocString.Content)
 
 	case *messages.PickleStepArgument_DataTable:
 		for _, row := range msg.DataTable.Rows {
 			for _, cell := range row.Cells {
-				cell.Value = expand(cell.Value)
+				cell.Value = doExpand(expand, cell.Value)
 			}
 		}
 	}