sweep: adjust TestNegativeInput after fee rate buckets integration

With the introduction of the fee rate buckets, fee rates for sweeps are
no longer re-queried when scheduling new input requests/sweeps. Because
of this, we can no longer test the case where an input with a negative
yield is included in a transaction once fees have decreased.

sweep/sweeper_test.go

@@ -356,8 +356,7 @@ func TestNegativeInput(t *testing.T) {
 	// the HtlcAcceptedRemoteSuccess input type adds more in fees than its
 	// value at the current fee level.
 	negInput := createTestInput(2900, input.HtlcOfferedRemoteTimeout)
-	negInputResult, err := ctx.sweeper.SweepInput(&negInput, nil)
-	if err != nil {
+	if _, err := ctx.sweeper.SweepInput(&negInput, nil); err != nil {
 		t.Fatal(err)
 	}
 
@@ -373,7 +372,7 @@ func TestNegativeInput(t *testing.T) {
 
 	// We expect that a sweep tx is published now, but it should only
 	// contain the large input. The negative input should stay out of sweeps
-	// until fees come down to get a positive net yield.
+	// since it has a negative yield.
 	sweepTx1 := ctx.receiveTx()
 	assertTxSweepsInputs(t, &sweepTx1, &largeInput, &positiveInput)
 
@@ -382,10 +381,8 @@ func TestNegativeInput(t *testing.T) {
 	ctx.expectResult(largeInputResult, nil)
 	ctx.expectResult(positiveInputResult, nil)
 
-	// Lower fee rate so that the negative input is no longer negative.
-	ctx.estimator.updateFees(1000, 1000)
-
-	// Create another large input
+	// Sweeping another large input should result in the negative yield
+	// still not being swept.
 	secondLargeInput := createTestInput(100000, input.CommitmentNoDelay)
 	secondLargeInputResult, err := ctx.sweeper.SweepInput(
 		&secondLargeInput, nil,
@@ -402,9 +399,10 @@ func TestNegativeInput(t *testing.T) {
 	ctx.backend.mine()
 
 	ctx.expectResult(secondLargeInputResult, nil)
-	ctx.expectResult(negInputResult, nil)
 
-	ctx.finish(1)
+	// The negative input's waitForSpend goroutine should still be lingering
+	// since it hasn't been swept.
+	ctx.finish(2)
 }
 
 // TestChunks asserts that large sets of inputs are split into multiple txes.