Crussell/backend/handlers/payments/validators_test.go

//go:build test && dev

package payments

import (
	"strings"
	"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)
	}
}

// TestValidateCardInfo_SCACoexistence pins the SCA saved-card wire contract on
// the card-source validator: a saved-card reference (card_id or saved_card_id)
// riding along WITH new_card_token is now VALID — the tokenize-result token is
// the one-time charge source and the saved-card row supplies the customer
// (resolveChargeSource implements the coexistence). A card reference alone
// (legacy saved-card), a token alone (new-card), empty references, and neither
// present keep their prior semantics.
func TestValidateCardInfo_SCACoexistence(t *testing.T) {
	t.Parallel()

	cardID := "card-1"
	savedCardID := "card-2"
	token := "cnon:sca-tokenize"
	empty := ""

	// card_id + new_card_token — now valid (SCA tokenize-result source).
	require.NoError(t, ValidateCardInfo(&cardID, nil, &token),
		"card_id + new_card_token must be valid (SCA tokenize-result)")
	// saved_card_id + new_card_token — valid (SCA tokenize-result).
	require.NoError(t, ValidateCardInfo(nil, &savedCardID, &token),
		"saved_card_id + new_card_token must be valid (SCA tokenize-result)")
	// card_id only — valid legacy saved-card charge.
	require.NoError(t, ValidateCardInfo(&cardID, nil, nil),
		"card_id alone must remain valid")
	// new_card_token only — valid new-card charge.
	require.NoError(t, ValidateCardInfo(nil, nil, &token),
		"a bare new_card_token must remain valid (new-card path)")
	// Neither present — invalid.
	require.Error(t, ValidateCardInfo(nil, nil, nil),
		"neither a card reference nor new_card_token must be rejected")
	// Empty strings are treated as absent — invalid when nothing is present.
	require.Error(t, ValidateCardInfo(&empty, &empty, &empty),
		"empty-string values must be rejected as absent")
	require.Error(t, ValidateCardInfo(&empty, nil, &empty),
		"an empty card_id with an empty token must be rejected")
	// An empty card reference with a real token is still the valid new-card path.
	require.NoError(t, ValidateCardInfo(&empty, nil, &token),
		"an empty card_id with a real new_card_token is the new-card path and must be valid")
}

// TestValidateCardInfo_Table covers the full card-source shape space as a table:
// the three legal wire shapes (saved-card reference only, new-card token only,
// and both together as the SCA tokenize-result source) plus the both-absent and
// empty-string rejections. This is the drift guard for the SCA wire contract —
// every shape the frontend can send is enumerated here.
func TestValidateCardInfo_Table(t *testing.T) {
	t.Parallel()

	cardID := "card-1"
	savedCardID := "saved-2"
	token := "cnon:sca-tokenize-3"
	empty := ""

	tests := []struct {
		name      string
		cardID    *string
		savedCard *string
		token     *string
		wantValid bool
	}{
		{"saved card reference (card_id) only — legacy saved-card charge", &cardID, nil, nil, true},
		{"saved card reference (saved_card_id) only", nil, &savedCardID, nil, true},
		{"new card token only — new-card charge", nil, nil, &token, true},
		{"saved-card reference + new card token — SCA tokenize-result source", &cardID, nil, &token, true},
		{"saved_card_id + new card token — SCA tokenize-result source", nil, &savedCardID, &token, true},
		{"neither present — invalid", nil, nil, nil, false},
		{"empty card_id + empty saved_card_id + empty token — all absent", &empty, &empty, &empty, false},
		{"empty card_id + empty token — absent card ref", &empty, nil, &empty, false},
		{"empty saved_card_id + empty token — absent card ref", nil, &empty, &empty, false},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			err := ValidateCardInfo(tt.cardID, tt.savedCard, tt.token)
			if tt.wantValid {
				require.NoErrorf(t, err, "expected shape to be valid: %v", tt)
			} else {
				require.Errorf(t, err, "expected shape to be rejected: %v", tt)
			}
		})
	}
}

// TestValidatePartialAmount_PenceSemantics pins the pence comparison: amounts
// are integer pence, so the boundary is exact — equal pence passes, one penny
// over fails, and non-positive amounts are rejected regardless of the balance.
func TestValidatePartialAmount_PenceSemantics(t *testing.T) {
	t.Parallel()

	tests := []struct {
		name        string
		amountPence int64
		remaining   int64
		wantValid   bool
	}{
		{"partial equal to the remaining balance passes", 2500, 2500, true},
		{"partial below the remaining balance passes", 1000, 2500, true},
		{"one penny over the remaining balance fails", 2501, 2500, false},
		{"large partial over the balance fails", 5000, 2500, false},
		{"zero amount rejected even with balance", 0, 2500, false},
		{"negative amount rejected", -100, 2500, false},
		{"zero remaining rejects any positive partial", 1, 0, false},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			err := ValidatePartialAmount(tt.amountPence, tt.remaining)
			if tt.wantValid {
				require.NoErrorf(t, err, "expected %d pence against %d remaining to be valid", tt.amountPence, tt.remaining)
			} else {
				require.Errorf(t, err, "expected %d pence against %d remaining to be rejected", tt.amountPence, tt.remaining)
			}
		})
	}
}

// TestValidateVerificationToken_Bound pins the 512-char bound on Square's
// verification token: empty/nil is fine (token-less charges are valid input),
// anything at or under 512 chars passes, and 513+ is rejected.
func TestValidateVerificationToken_Bound(t *testing.T) {
	t.Parallel()

	ok := strings.Repeat("t", 512)
	tooLong := strings.Repeat("t", 513)

	tests := []struct {
		name    string
		token   *string
		wantErr bool
	}{
		{"nil token passes (token-less is valid)", nil, false},
		{"empty token passes", strPtr(""), false},
		{"exactly 512 chars passes", &ok, false},
		{"513 chars rejected", &tooLong, true},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			err := ValidateVerificationToken(tt.token)
			if tt.wantErr {
				require.Error(t, err)
			} else {
				require.NoError(t, err)
			}
		})
	}
}