Crussell/backend/handlers/webhooks/webhooks_dispatch_error_test.go

//go:build test

package webhooks

// Regression test for the at-least-once webhook delivery contract: a dispatch
// error must NOT commit the dedup row, so Square's retry is not swallowed.

import (
	"encoding/json"
	"net/http"
	"testing"
)

// TestHandleSquareWebhook_DispatchError_NoDedup_RetryReDispatches verifies the
// handler's dispatch-first/commit-dedup-after order: when the dispatch handler
// errors (here the disputes INSERT fails because the amount overflows
// NUMERIC(10,2)), the handler returns 503 and records NO dedup row — so a
// replayed delivery (Square's retry) is re-dispatched, not 200-skipped. Before
// the at-least-once ordering this invariant silently dropped events on any
// transient dispatch failure.
func TestHandleSquareWebhook_DispatchError_NoDedup_RetryReDispatches(t *testing.T) {
	const squarePaymentID = "sqp_dispatch_err"
	_ = createWebhookTestPayment(t, squarePaymentID, "completed")

	// amount_money.amount = 9,999,999,999,999,999 pence → £99,999,999,999,999.99,
	// far beyond disputes.amount NUMERIC(10,2) — the INSERT fails.
	overflowEvent := SquareWebhookEvent{
		Type:      "dispute.created",
		EventID:   "evt_dispatch_err_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data: json.RawMessage(`{
			"type": "dispute",
			"id": "dts_dispatch_err_1",
			"object": {
				"dispute": {
					"id": "dts_dispatch_err_1",
					"state": "UNDER_REVIEW",
					"amount_money": {"amount": 9999999999999999, "currency": "GBP"},
					"reason": "OVERFLOW",
					"disputed_payment": {"payment_id": "` + squarePaymentID + `"}
				}
			}
		}`),
	}

	w1 := deliverWebhook(t, overflowEvent)
	if w1.Code != http.StatusServiceUnavailable {
		t.Fatalf("expected 503 on dispatch error, got %d: %s", w1.Code, w1.Body.String())
	}
	if n := countWebhookEvents(t, overflowEvent.EventID); n != 0 {
		t.Fatalf("expected NO dedup row after a dispatch error (Square must retry), got %d", n)
	}

	// Square retries with a well-formed payload under the SAME event_id.
	retryEvent := SquareWebhookEvent{
		Type:      "dispute.created",
		EventID:   "evt_dispatch_err_1",
		CreatedAt: "2025-01-01T00:00:00Z",
		Data: json.RawMessage(`{
			"type": "dispute",
			"id": "dts_dispatch_err_1",
			"object": {
				"dispute": {
					"id": "dts_dispatch_err_1",
					"state": "UNDER_REVIEW",
					"amount_money": {"amount": 1234, "currency": "GBP"},
					"reason": "NO_KNOWLEDGE",
					"disputed_payment": {"payment_id": "` + squarePaymentID + `"}
				}
			}
		}`),
	}
	w2 := deliverWebhook(t, retryEvent)
	if w2.Code != http.StatusOK {
		t.Fatalf("expected retry 200, got %d: %s", w2.Code, w2.Body.String())
	}
	if got := getDisputeStatus(t, "dts_dispatch_err_1"); got != "open" {
		t.Errorf("expected retried dispute to be recorded with status 'open', got %q", got)
	}
	if n := countWebhookEvents(t, retryEvent.EventID); n != 1 {
		t.Errorf("expected exactly 1 dedup row after the successful retry, got %d", n)
	}
}