[WIP] loop-ins: fix route hints passing, add test coverage by starius · Pull Request #1122 · lightninglabs/loop

starius · 2026-04-15T00:02:47Z

Pull Request Checklist

Update release_notes.md if your PR contains major features, breaking changes or bugfixes

Include lightninglabs/lndclient#268 Preserve AddInvoiceData fields across invoice wrappers TODO: remove go replace.

gemini-code-assist · 2026-04-15T00:02:55Z

Summary of Changes

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This pull request addresses an issue where route hints were being dropped during the loop-in swap invoice creation process. By updating the test infrastructure to properly handle and verify route hints, the changes ensure that these hints are correctly propagated, improving the reliability of loop-in payments. The PR also includes new test cases to prevent future regressions in this area.

Highlights

Route Hint Propagation: Updated the invoice creation logic in test mocks to correctly include and propagate route hints, ensuring they are preserved in loop-in swap invoices.
Test Coverage: Added new regression tests, 'TestLoopInSwapInvoiceRouteHintsMatchProbe' and 'TestInitHtlcActionPreservesRouteHints', to verify that route hints are correctly handled in both standard and static-address loop-in scenarios.
Dependency Update: Updated the 'lndclient' dependency to a custom fork to support the necessary changes for route hint passing.

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Code Review

This pull request updates the lndclient dependency to a fork and introduces regression tests to ensure that route hints are correctly preserved in loop-in invoices for both standard and static-address swaps. The changes include updates to test mocks to support route hint encoding in generated invoices. Review feedback suggests improving test context management by using t.Context() and deduplicating the requireRouteHintsEqual helper function by moving it to a shared utility package.

gemini-code-assist · 2026-04-15T00:05:46Z

+	req := testLoopInRequest
+	req.RouteHints = testLoopInRouteHints()
+
+	_, err := newLoopInSwap(context.Background(), cfg, 600, &req)


Use t.Context() instead of context.Background() to ensure the context is properly managed by the test runner. This provides automatic cancellation if the test times out and is the recommended practice for Go 1.24+.

Suggested change

_, err := newLoopInSwap(context.Background(), cfg, 600, &req)

_, err := newLoopInSwap(t.Context(), cfg, 600, &req)

gemini-code-assist · 2026-04-15T00:05:46Z

+func requireRouteHintsEqual(t *testing.T, expected, actual [][]zpay32.HopHint) {
+	t.Helper()
+
+	require.Len(t, actual, len(expected))
+
+	for i := range expected {
+		require.Len(t, actual[i], len(expected[i]))
+
+		for j := range expected[i] {
+			expectedHint := expected[i][j]
+			actualHint := actual[i][j]
+
+			require.Equal(
+				t,
+				expectedHint.NodeID.SerializeCompressed(),
+				actualHint.NodeID.SerializeCompressed(),
+			)
+			require.Equal(t, expectedHint.ChannelID, actualHint.ChannelID)
+			require.Equal(t, expectedHint.FeeBaseMSat,
+				actualHint.FeeBaseMSat)
+			require.Equal(t,
+				expectedHint.FeeProportionalMillionths,
+				actualHint.FeeProportionalMillionths)
+			require.Equal(t, expectedHint.CLTVExpiryDelta,
+				actualHint.CLTVExpiryDelta)
+		}
+	}
+}


The requireRouteHintsEqual helper function is duplicated in staticaddr/loopin/actions_test.go. Consider moving it to a shared test utility package (e.g., github.com/lightninglabs/loop/test) to improve maintainability and follow the DRY (Don't Repeat Yourself) principle.

gemini-code-assist · 2026-04-15T00:05:46Z

+		loopIn: loopIn,
+	}
+
+	event := f.InitHtlcAction(context.Background(), nil)


Use t.Context() instead of context.Background() for consistency with other tests in this file (e.g., line 33) and to ensure proper context lifecycle management during the test execution.

Suggested change

event := f.InitHtlcAction(context.Background(), nil)

event := f.InitHtlcAction(t.Context(), nil)

hieblmi

LGTM, pending go.mod replace after lndclient is merged.

hieblmi · 2026-04-15T07:56:01Z


 replace github.com/lightninglabs/loop/looprpc => ./looprpc

+replace github.com/lightninglabs/lndclient => github.com/starius/lndclient v0.20.0-7-addinvoice


reminder to remove and upgrade lndclient once it is merged and tagged.

go.mod: pin fixed lndclient addinvoice hints

8f51d65

Include lightninglabs/lndclient#268 Preserve AddInvoiceData fields across invoice wrappers TODO: remove go replace.

starius requested a review from hieblmi April 15, 2026 00:03

gemini-code-assist bot reviewed Apr 15, 2026

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starius added 3 commits April 15, 2026 00:41

test: add route hint assertion helper

71aa10f

loop+test: add loop-in route hint regression

2032d79

staticaddr/loopin: add route hint regression test

3e6cb16

starius force-pushed the addinvoice-coverage branch from c6644b2 to 3e6cb16 Compare April 15, 2026 05:41

starius marked this pull request as ready for review April 15, 2026 06:43

hieblmi approved these changes Apr 15, 2026

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hieblmi reviewed Apr 15, 2026

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[WIP] loop-ins: fix route hints passing, add test coverage#1122

[WIP] loop-ins: fix route hints passing, add test coverage#1122
starius wants to merge 4 commits intolightninglabs:masterfrom
starius:addinvoice-coverage

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	_, err := newLoopInSwap(context.Background(), cfg, 600, &req)
	_, err := newLoopInSwap(t.Context(), cfg, 600, &req)

	event := f.InitHtlcAction(context.Background(), nil)
	event := f.InitHtlcAction(t.Context(), nil)


		replace github.com/lightninglabs/loop/looprpc => ./looprpc

		replace github.com/lightninglabs/lndclient => github.com/starius/lndclient v0.20.0-7-addinvoice

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starius commented Apr 15, 2026

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