make alloc zero alloc test more stable

Makefile

@@ -46,7 +46,7 @@ memprofile:
 noallocsprofile:
 	rm mem.out || true
 	rm profile*.* || true
-	go test -test.v -test.run=TestNotASingleAllocAfterWarmUp -test.memprofile=mem.out ./json
+	(go test -test.v -test.run=TestNotASingleAllocAfterWarmUp -test.memprofile=mem.out ./json || true)
 	(cd json && go test -c -gcflags="-m" 2>&1 | grep "escapes" | grep -Ev "(_test.go|_testmain.go|autogenerated)")
 	go tool pprof -alloc_space -png mem.out
 

json/alloc_test.go

@@ -61,28 +61,30 @@ func TestNotASingleAllocAfterWarmUp(t *testing.T) {
 	// warm up buffer pool
 	for i := 0; i < num; i++ {
 		if err := jparser.Init(js[i%num]); err != nil {
-			t.Fatalf("seed = %v, err = %v", seed, err)
+			t.Fatalf("seed = %v, err = %v value = %v", seed, err, string(js[i%num]))
 		}
 		walk(jparser)
 	}
 	originalPoolSize := pool.Size()
 
 	const runsPerTest = 1
-	checkNoAllocs := func(f func()) func(t *testing.T) {
-		return func(t *testing.T) {
-			t.Helper()
-			if allocs := testing.AllocsPerRun(runsPerTest, f); allocs != 0 {
-				t.Errorf("seed = %v, got %v allocs, want 0 allocs, pool allocs = %v", seed, allocs, pool.Size()-originalPoolSize)
-			}
-		}
-	}
 	for i := 0; i < num; i++ {
-		t.Run(fmt.Sprintf("%d", i), checkNoAllocs(func() {
+		f := func() {
 			if err := jparser.Init(js[i]); err != nil {
 				t.Fatalf("seed = %v, err = %v", seed, err)
 			}
 			walk(jparser)
-		}))
+		}
+		allocs := testing.AllocsPerRun(runsPerTest, f)
+		if allocs != 0 {
+			poolallocs := pool.Size() - originalPoolSize
+			// there are sometimes allocations made by the testing framework
+			// retry to make sure that the allocation is the parser's fault.
+			allocs2 := testing.AllocsPerRun(runsPerTest, f)
+			if allocs2 != 0 {
+				t.Errorf("seed = %v, got %v allocs, want 0 allocs, pool allocs = %v", seed, allocs, poolallocs)
+			}
+		}
 	}
 }
 

json/rand_test.go

@@ -24,7 +24,6 @@ import (
 
 func TestParseRandom(t *testing.T) {
 	seed := time.Now().UnixNano()
-	seed = 1738425704510828000 // TODO remove this line
 	num := 10000
 	r := rand.New(rand.NewSource(seed))
 	js := randJsons(r, num)
@@ -264,13 +263,13 @@ func randWs(r *rand.Rand) string {
 func randW(r *rand.Rand) rune {
 	switch r.Intn(4) {
 	case 0:
-		return '\u0020'
+		return '\u0020' // space
 	case 1:
-		return '\u000A'
+		return '\u000A' // \n
 	case 2:
-		return '\u000D'
+		return '\u000D' // \r
 	case 3:
-		return '\u0009'
+		return '\u0009' // \t
 	}
 	panic("unreachable")
 }