utils: fix mermaid output.

utils.go

@@ -42,12 +42,12 @@ func visualizeForMermaid(fsm *FSM) string {
 		return sortedEKeys[i].src < sortedEKeys[j].src
 	})
 
-	buf.WriteString(fmt.Sprintf(`graph fsm`))
-	buf.WriteString("\n")
+	buf.WriteString("stateDiagram\n")
+	buf.WriteString(fmt.Sprintln(`    [*] -->`, fsm.current))
 
 	for _, k := range sortedEKeys {
 		v := fsm.transitions[k]
-		buf.WriteString(fmt.Sprintf(`    %s -->|%s| %s`, k.src, k.event, v))
+		buf.WriteString(fmt.Sprintf(`    %s --> %s: %s`, k.src, v, k.event))
 		buf.WriteString("\n")
 	}
 

utils_test.go

@@ -53,10 +53,11 @@ func TestMermaidOutput(t *testing.T) {
 		t.Errorf("got error for visualizing with type MERMAID: %s", err)
 	}
 	wanted := `
-graph fsm
-    closed -->|open| open
-    intermediate -->|part-close| closed
-    open -->|close| closed
+stateDiagram
+    [*] --> closed
+    closed --> open: open
+    intermediate --> closed: part-close
+    open --> closed: close
 `
 	normalizedGot := strings.ReplaceAll(got, "\n", "")
 	normalizedWanted := strings.ReplaceAll(wanted, "\n", "")