more tests

cmd/cart/price_test.go

@@ -32,6 +32,19 @@ func TestPriceMarshalJSON(t *testing.T) {
 	}
 }
 
+func TestNewPriceFromIncVat(t *testing.T) {
+	p := NewPriceFromIncVat(1000, 0.25)
+	if p.IncVat != 1000 {
+		t.Fatalf("expected IncVat %d got %d", 1000, p.IncVat)
+	}
+	if p.VatRates[25] != 250 {
+		t.Fatalf("expected VAT 25 rate %d got %d", 250, p.VatRates[25])
+	}
+	if p.ValueExVat() != 750 {
+		t.Fatalf("expected exVat %d got %d", 750, p.ValueExVat())
+	}
+}
+
 func TestSumPrices(t *testing.T) {
 	// We'll construct prices via raw struct since constructor expects tax math.
 	// IncVat already includes vat portions.