itest: shuffle test cases to even out blocks mined in tranches

This commit shuffles all the test cases before running them so tests
which require lots of blocks to be mined are less likely to be run in
the same tranch.

The other benefit is this approach provides a more efficient way to
figure which tests are broken since all the differnet backends are
running different tranches in their builds, we can identify more failed
tests in one push.

itest/list_on_test.go

@@ -2,7 +2,11 @@
 
 package itest
 
-import "github.com/lightningnetwork/lnd/lntest"
+import (
+	"math/rand"
+
+	"github.com/lightningnetwork/lnd/lntest"
+)
 
 var allTestCases = []*lntest.TestCase{
 	{
@@ -683,4 +687,12 @@ var allTestCases = []*lntest.TestCase{
 func init() {
 	// Register subtests.
 	allTestCases = append(allTestCases, multiHopForceCloseTestCases...)
+
+	// Shuffle the test cases so they are executed in a random order. This
+	// is done to even out the blocks mined in each test tranche so they
+	// can run faster.
+	rand.Shuffle(len(allTestCases), func(i, j int) {
+		allTestCases[i], allTestCases[j] =
+			allTestCases[j], allTestCases[i]
+	})
 }

itest/lnd_payment_test.go

@@ -466,17 +466,15 @@ func testSendDirectPayment(ht *lntest.HarnessTest) {
 }
 
 func testListPayments(ht *lntest.HarnessTest) {
-	alice, bob := ht.Alice, ht.Bob
-
-	// Check that there are no payments before test.
-	ht.AssertNumPayments(alice, 0)
+	// Prepare test params.
+	chanAmt := btcutil.Amount(100000)
+	params := lntest.OpenChannelParams{Amt: chanAmt}
 
 	// Open a channel with 100k satoshis between Alice and Bob with Alice
-	// being the sole funder of the channel.
-	chanAmt := btcutil.Amount(100000)
-	chanPoint := ht.OpenChannel(
-		alice, bob, lntest.OpenChannelParams{Amt: chanAmt},
-	)
+	// being the sole funder of the channel. We use fresh nodes here so
+	// they don't have old invoices or payments.
+	chanPoints, nodes := createSimpleNetwork(ht, nil, 2, params)
+	alice, bob := nodes[0], nodes[1]
 
 	// Now that the channel is open, create an invoice for Bob which
 	// expects a payment of 1000 satoshis from Alice paid via a particular
@@ -645,7 +643,7 @@ func testListPayments(ht *lntest.HarnessTest) {
 	time.Sleep(2 * time.Second)
 
 	// Close the channel.
-	ht.CloseChannel(alice, chanPoint)
+	ht.CloseChannel(alice, chanPoints[0])
 }
 
 // testPaymentFollowingChannelOpen tests that the channel transition from