mining: Improve tests for prio queue. (decred#667)

This improves the tests of the priority queue to include the secondary
sort ordering as well as adds some manual entries to ensure the edge
conditions are properly tested.

This also brings the priority queue test coverage up to 100%.

mining_test.go

@@ -15,51 +15,96 @@ import (
 // TestTxFeePrioHeap ensures the priority queue for transaction fees and
 // priorities works as expected.
 func TestTxFeePrioHeap(t *testing.T) {
-	// Create priority items with random fees and priorites.
-	const numItems = 1000
-	prioItems := make([]*txPrioItem, numItems)
-	highestFeePerKB := int64(0)
-	highestPrio := float64(0)
-	for i := 0; i < 1000; i++ {
-		randPrio := rand.Float64() * 100
-		if randPrio > highestPrio {
-			highestPrio = randPrio
+	// Create some fake priority items that exercise the expected sort
+	// edge conditions.
+	testItems := []*txPrioItem{
+		{feePerKB: 5678, priority: 3},
+		{feePerKB: 5678, priority: 1},
+		{feePerKB: 5678, priority: 1}, // Duplicate fee and prio
+		{feePerKB: 5678, priority: 5},
+		{feePerKB: 5678, priority: 2},
+		{feePerKB: 1234, priority: 3},
+		{feePerKB: 1234, priority: 1},
+		{feePerKB: 1234, priority: 5},
+		{feePerKB: 1234, priority: 5}, // Duplicate fee and prio
+		{feePerKB: 1234, priority: 2},
+		{feePerKB: 10000, priority: 0}, // Higher fee, smaller prio
+		{feePerKB: 0, priority: 10000}, // Higher prio, lower fee
+	}
+
+	// Add random data in addition to the edge conditions already manually
+	// specified.
+	randSeed := rand.Int63()
+	defer func() {
+		if t.Failed() {
+			t.Logf("Random numbers using seed: %v", randSeed)
 		}
-		randFeePerKB := int64(rand.Float64() * btcutil.SatoshiPerBitcoin)
-		if randFeePerKB > highestFeePerKB {
-			highestFeePerKB = randFeePerKB
+	}()
+	prng := rand.New(rand.NewSource(randSeed))
+	for i := 0; i < 1000; i++ {
+		testItems = append(testItems, &txPrioItem{
+			feePerKB: int64(prng.Float64() * btcutil.SatoshiPerBitcoin),
+			priority: prng.Float64() * 100,
+		})
+	}
+
+	// Test sorting by fee per KB then priority.
+	var highest *txPrioItem
+	priorityQueue := newTxPriorityQueue(len(testItems), true)
+	for i := 0; i < len(testItems); i++ {
+		prioItem := testItems[i]
+		if highest == nil {
+			highest = prioItem
 		}
-		prioItems[i] = &txPrioItem{
-			tx:       nil,
-			priority: randPrio,
-			feePerKB: randFeePerKB,
+		if prioItem.feePerKB >= highest.feePerKB &&
+			prioItem.priority > highest.priority {
+
+			highest = prioItem
 		}
+		heap.Push(priorityQueue, prioItem)
 	}
 
-	// Test sorting by fee per KB.
-	priorityQueue := newTxPriorityQueue(numItems, true)
-	for i := 0; i < numItems; i++ {
-		heap.Push(priorityQueue, prioItems[i])
-	}
-	for i := 0; i < numItems; i++ {
+	for i := 0; i < len(testItems); i++ {
 		prioItem := heap.Pop(priorityQueue).(*txPrioItem)
-		if prioItem.feePerKB > highestFeePerKB {
-			t.Fatalf("bad pop: %v fee per KB was more than last of %v",
-				prioItem.feePerKB, highestFeePerKB)
+		if prioItem.feePerKB >= highest.feePerKB &&
+			prioItem.priority > highest.priority {
+
+			t.Fatalf("fee sort: item (fee per KB: %v, "+
+				"priority: %v) higher than than prev "+
+				"(fee per KB: %v, priority %v)",
+				prioItem.feePerKB, prioItem.priority,
+				highest.feePerKB, highest.priority)
 		}
-		highestFeePerKB = prioItem.feePerKB
+		highest = prioItem
 	}
 
-	// Test sorting by priority.
-	priorityQueue = newTxPriorityQueue(numItems, false)
-	for i := 0; i < numItems; i++ {
-		heap.Push(priorityQueue, prioItems[i])
+	// Test sorting by priority then fee per KB.
+	highest = nil
+	priorityQueue = newTxPriorityQueue(len(testItems), false)
+	for i := 0; i < len(testItems); i++ {
+		prioItem := testItems[i]
+		if highest == nil {
+			highest = prioItem
+		}
+		if prioItem.priority >= highest.priority &&
+			prioItem.feePerKB > highest.feePerKB {
+
+			highest = prioItem
+		}
+		heap.Push(priorityQueue, prioItem)
 	}
-	for i := 0; i < numItems; i++ {
+
+	for i := 0; i < len(testItems); i++ {
 		prioItem := heap.Pop(priorityQueue).(*txPrioItem)
-		if prioItem.priority > highestPrio {
-			t.Fatalf("bad pop: %v priority was more than last of %v",
-				prioItem.priority, highestPrio)
+		if prioItem.priority >= highest.priority &&
+			prioItem.feePerKB > highest.feePerKB {
+
+			t.Fatalf("priority sort: item (fee per KB: %v, "+
+				"priority: %v) higher than than prev "+
+				"(fee per KB: %v, priority %v)",
+				prioItem.feePerKB, prioItem.priority,
+				highest.feePerKB, highest.priority)
 		}
+		highest = prioItem
 	}
 }