优化结构

internal/paymentkit/amount_test.go

@@ -0,0 +1,25 @@
+package paymentkit
+
+import "testing"
+
+func TestDecimalAmountUsesIntegerMath(t *testing.T) {
+	got, err := ParseDecimalAmount("12.34", 100)
+	if err != nil || got != 1234 {
+		t.Fatalf("ParseDecimalAmount = %d, %v", got, err)
+	}
+	formatted, err := FormatDecimalAmount(got, 100)
+	if err != nil || formatted != "12.34" {
+		t.Fatalf("FormatDecimalAmount = %q, %v", formatted, err)
+	}
+}
+
+func TestDecimalAmountRejectsUnsafeInput(t *testing.T) {
+	for _, value := range []string{"-1.00", "1.001", "1.2.3"} {
+		if _, err := ParseDecimalAmount(value, 100); err == nil {
+			t.Fatalf("ParseDecimalAmount(%q) accepted unsafe input", value)
+		}
+	}
+	if _, err := ParseDecimalAmount("1", 3); err == nil {
+		t.Fatal("non power-of-ten scale accepted")
+	}
+}