//go:build test && dev

package payments

import (
	"testing"

	"github.com/stretchr/testify/require"
)

// TestValidateAmount covers the amount validator used by every payment
// handler: positive and within the £10,000 (1,000,000 pence) cap. Amounts are
// integer pence, so sub-penny "precision" is impossible by construction.
func TestValidateAmount(t *testing.T) {
	t.Parallel()

	valid := []int64{1, 500, 10000, 999999, 1000000}
	for _, amount := range valid {
		require.NoErrorf(t, ValidateAmount(amount), "expected %d to be a valid amount", amount)
	}

	invalid := []int64{0, -1, -500, 1000001}
	for _, amount := range invalid {
		require.Errorf(t, ValidateAmount(amount), "expected %d to be rejected", amount)
	}

	// The cap is exclusive: exactly £10,000 (1,000,000 pence) is allowed, one
	// penny more is rejected.
	if err := ValidateAmount(1000001); err == nil {
		t.Error("expected amount above £10,000 cap to be rejected")
	}
	if err := ValidateAmount(1000000); err != nil {
		t.Errorf("expected exactly £10,000 to be allowed, got %v", err)
	}
}