Merge pull request #2495 from halseth/itest-dont-shadow-prederr

[trivial] lnd_test: don't shadow predErr

lnd_test.go

@@ -2705,27 +2705,26 @@ func testChannelForceClosure(net *lntest.NetworkHarness, t *harnessTest) {
 
 	// Alice should see the channel in her set of pending force closed
 	// channels with her funds still in limbo.
-	err = lntest.WaitPredicate(func() bool {
+	err = lntest.WaitNoError(func() error {
 		ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
 		pendingChanResp, err := net.Alice.PendingChannels(
 			ctxt, pendingChansRequest,
 		)
 		if err != nil {
-			predErr = fmt.Errorf("unable to query for pending "+
+			return fmt.Errorf("unable to query for pending "+
 				"channels: %v", err)
-			return false
 		}
 
-		predErr = checkNumForceClosedChannels(pendingChanResp, 1)
-		if predErr != nil {
-			return false
+		err = checkNumForceClosedChannels(pendingChanResp, 1)
+		if err != nil {
+			return err
 		}
 
-		forceClose, predErr := findForceClosedChannel(
+		forceClose, err := findForceClosedChannel(
 			pendingChanResp, &op,
 		)
-		if predErr != nil {
-			return false
+		if err != nil {
+			return err
 		}
 
 		// At this point, the nursery should show that the commitment
@@ -2733,29 +2732,27 @@ func testChannelForceClosure(net *lntest.NetworkHarness, t *harnessTest) {
 		// total, we have mined exactly defaultCSV blocks, so the htlc
 		// outputs should also reflect that this many blocks have
 		// passed.
-		predErr = checkCommitmentMaturity(
+		err = checkCommitmentMaturity(
 			forceClose, commCsvMaturityHeight, 1,
 		)
-		if predErr != nil {
-			return false
+		if err != nil {
+			return err
 		}
 
 		// All funds should still be shown in limbo.
 		if forceClose.LimboBalance == 0 {
-			predErr = errors.New("all funds should still be in " +
+			return errors.New("all funds should still be in " +
 				"limbo")
-			return false
 		}
 		if forceClose.RecoveredBalance != 0 {
-			predErr = errors.New("no funds should yet be shown " +
+			return errors.New("no funds should yet be shown " +
 				"as recovered")
-			return false
 		}
 
-		return true
+		return nil
 	}, 15*time.Second)
 	if err != nil {
-		t.Fatalf(predErr.Error())
+		t.Fatalf(err.Error())
 	}
 
 	// Generate an additional block, which should cause the CSV delayed
@@ -2875,40 +2872,39 @@ func testChannelForceClosure(net *lntest.NetworkHarness, t *harnessTest) {
 
 	// Alice should now see the channel in her set of pending force closed
 	// channels with one pending HTLC.
-	err = lntest.WaitPredicate(func() bool {
+	err = lntest.WaitNoError(func() error {
 		ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
 		pendingChanResp, err := net.Alice.PendingChannels(
 			ctxt, pendingChansRequest,
 		)
 		if err != nil {
-			predErr = fmt.Errorf("unable to query for pending "+
+			return fmt.Errorf("unable to query for pending "+
 				"channels: %v", err)
-			return false
 		}
 
-		predErr = checkNumForceClosedChannels(pendingChanResp, 1)
-		if predErr != nil {
-			return false
+		err = checkNumForceClosedChannels(pendingChanResp, 1)
+		if err != nil {
+			return err
 		}
 
-		forceClose, predErr := findForceClosedChannel(
+		forceClose, err := findForceClosedChannel(
 			pendingChanResp, &op,
 		)
-		if predErr != nil {
-			return false
+		if err != nil {
+			return err
 		}
 
 		// We should now be at the block just before the utxo nursery
 		// will attempt to broadcast the htlc timeout transactions.
-		predErr = checkPendingChannelNumHtlcs(forceClose, numInvoices)
-		if predErr != nil {
-			return false
+		err = checkPendingChannelNumHtlcs(forceClose, numInvoices)
+		if err != nil {
+			return err
 		}
-		predErr = checkPendingHtlcStageAndMaturity(
+		err = checkPendingHtlcStageAndMaturity(
 			forceClose, 1, htlcExpiryHeight, 1,
 		)
-		if predErr != nil {
-			return false
+		if err != nil {
+			return err
 		}
 
 		// Now that our commitment confirmation depth has been
@@ -2916,15 +2912,14 @@ func testChannelForceClosure(net *lntest.NetworkHarness, t *harnessTest) {
 		// All htlc outputs are still left in limbo, so it should be
 		// non-zero as well.
 		if forceClose.LimboBalance == 0 {
-			predErr = errors.New("htlc funds should still be in " +
+			return errors.New("htlc funds should still be in " +
 				"limbo")
-			return false
 		}
 
-		return true
+		return nil
 	}, 15*time.Second)
 	if err != nil {
-		t.Fatalf(predErr.Error())
+		t.Fatalf(err.Error())
 	}
 
 	// Now, generate the block which will cause Alice to broadcast the

lntest/harness.go

@@ -1155,6 +1155,28 @@ func WaitPredicate(pred func() bool, timeout time.Duration) error {
 	}
 }
 
+// WaitNoError is a wrapper around WaitPredicate that waits for the passed
+// method f to execute without error, and returns the last error encountered if
+// this doesn't happen within the timeout.
+func WaitNoError(f func() error, timeout time.Duration) error {
+	var predErr error
+	pred := func() bool {
+		if err := f(); err != nil {
+			predErr = err
+			return false
+		}
+		return true
+	}
+
+	// If f() doesn't succeed within the timeout, return the last
+	// encountered error.
+	if err := WaitPredicate(pred, timeout); err != nil {
+		return predErr
+	}
+
+	return nil
+}
+
 // WaitInvariant is a helper test function that will wait for a timeout period
 // of time, verifying that a statement remains true for the entire duration.
 // This function is helpful as timing doesn't always line up well when running