diff --git a/step_test.go b/step_test.go
new file mode 100644
index 0000000..e0e489b
--- /dev/null
+++ b/step_test.go
@@ -0,0 +1,52 @@
+package expandog_test
+
+import (
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/cucumber/godog"
+	"github.com/stretchr/testify/assert"
+
+	"github.com/nhatthm/expandog"
+)
+
+func TestExpandStep(t *testing.T) {
+	t.Parallel()
+
+	expanders := []interface{}{
+		// Raw replacer.
+		strings.NewReplacer("$TO", "Berlin"),
+		// Our expanders.
+		expandog.Pairs{
+			"HUSBAND": "John",
+		},
+		func() expandog.Pairs {
+			return expandog.Pairs{
+				"WIFE": "Jane",
+			}
+		},
+		func(s string) string {
+			return strings.ReplaceAll(s, "$FROM", "Paris")
+		},
+		expandog.Expander(func(s string) string {
+			return strings.ReplaceAll(s, "$TRANSPORT", "by bus")
+		}),
+		// Os.
+		expandog.EnvExpander,
+	}
+
+	// Set os env.
+	assert.NoError(t, os.Setenv("GREETINGS", "Hi Dave"))
+
+	defer func() {
+		_ = os.Unsetenv("GREETINGS") // nolint:errcheck
+	}()
+
+	step := &godog.Step{Text: "$GREETINGS, $HUSBAND & $WIFE are going from $FROM to $TO $TRANSPORT"}
+	expected := "Hi Dave, John & Jane are going from Paris to Berlin by bus"
+
+	expandog.ExpandStep(step, expanders...)
+
+	assert.Equal(t, expected, step.Text)
+}