testing(lib/trie): change lib/trie slow and intensive benchmark-ori…

…ented tests to benchmarks (#2031)

- Change unit tests to a merged Go benchmark (you can run them with `go test -bench`)
- Use deepcopy to copy the trie instead of re-generating one, which takes time
- Use math/rand instead of crypto/rand to generate trie values faster

lib/trie/test_utils.go

@@ -6,7 +6,7 @@ package trie
 import (
 	"crypto/rand"
 	"encoding/binary"
-	"math/big"
+	prand "math/rand"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -35,37 +35,38 @@ func GenerateRandomTests(t testing.TB, size int) []Test {
 	rt := make([]Test, size)
 	kv := make(map[string][]byte)
 
+	const seed = 912378
+	generator := prand.New(prand.NewSource(seed)) //nolint:gosec
+
 	for i := range rt {
-		test := generateRandomTest(t, kv)
+		test := generateRandomTest(t, kv, generator)
 		rt[i] = test
 		kv[string(test.key)] = rt[i].value
 	}
 
 	return rt
 }
 
-func generateRandomTest(t testing.TB, kv map[string][]byte) Test {
+func generateRandomTest(t testing.TB, kv map[string][]byte, generator *prand.Rand) Test {
 	test := Test{}
 
 	for {
-		n := 2 // arbitrary positive number
-		size, err := rand.Int(rand.Reader, big.NewInt(510))
-		require.NoError(t, err)
+		var n int64 = 2 // arbitrary positive number
+		size := int64(generator.Intn(510))
 
-		buf := make([]byte, size.Int64()+int64(n))
-		_, err = rand.Read(buf)
+		buf := make([]byte, size+n)
+		_, err := generator.Read(buf)
 		require.NoError(t, err)
 
 		key := binary.LittleEndian.Uint16(buf[:2])
 
 		if kv[string(buf)] == nil || key < 256 {
 			test.key = buf
 
-			size, err := rand.Int(rand.Reader, big.NewInt(128))
-			require.NoError(t, err)
+			size := int64(generator.Intn(128))
 
-			buf = make([]byte, size.Int64()+int64(n))
-			_, err = rand.Read(buf)
+			buf = make([]byte, size+n)
+			_, err = generator.Read(buf)
 			require.NoError(t, err)
 
 			test.value = buf

lib/trie/trie_test.go

@@ -1116,39 +1116,43 @@ func TestNextKey_Random(t *testing.T) {
 	}
 }
 
-func TestRootHashNonParallel(t *testing.T) {
-	rt := GenerateRandomTests(t, 1000000)
+func Benchmark_Trie_Hash(b *testing.B) {
+	rt := GenerateRandomTests(b, 1000000)
 	trie := NewEmptyTrie()
 	for i := range rt {
 		test := &rt[i]
 		trie.Put(test.key, test.value)
 	}
 
-	t.Run("Non Parallel Hash", func(t *testing.T) {
+	trieTwo, err := trie.DeepCopy()
+	require.NoError(b, err)
+
+	b.Run("Sequential hash", func(b *testing.B) {
 		trie.parallel = false
+
+		b.StartTimer()
 		_, err := trie.Hash()
-		require.NoError(t, err)
-		PrintMemUsage()
+		b.StopTimer()
+
+		require.NoError(b, err)
+
+		printMemUsage()
 	})
-}
 
-func TestRootHashParallel(t *testing.T) {
-	rt := GenerateRandomTests(t, 1000000)
-	trie := NewEmptyTrie()
-	for i := range rt {
-		test := &rt[i]
-		trie.Put(test.key, test.value)
-	}
+	b.Run("Parallel hash", func(b *testing.B) {
+		trieTwo.parallel = true
 
-	t.Run("Parallel Hash", func(t *testing.T) {
-		trie.parallel = true
-		_, err := trie.Hash()
-		require.NoError(t, err)
-		PrintMemUsage()
+		b.StartTimer()
+		_, err := trieTwo.Hash()
+		b.StopTimer()
+
+		require.NoError(b, err)
+
+		printMemUsage()
 	})
 }
 
-func PrintMemUsage() {
+func printMemUsage() {
 	var m runtime.MemStats
 	runtime.ReadMemStats(&m)
 	// For info on each, see: https://golang.org/pkg/runtime/#MemStats