test: add coverage for mem usage in newArrayValues

builtin_arrray_test.go

@@ -1,6 +1,9 @@
 package goja
 
-import "testing"
+import (
+	"context"
+	"testing"
+)
 
 func TestArrayProtoProp(t *testing.T) {
 	const SCRIPT = `
@@ -338,3 +341,53 @@ func TestArrayProto(t *testing.T) {
 	`
 	testScriptWithTestLib(SCRIPT, _undefined, t)
 }
+
+func TestNewArrayValues(t *testing.T) {
+	for _, tc := range []struct {
+		name                string
+		memLimit            uint64
+		expectedPanic       bool
+		shouldForceMemCheck bool
+	}{
+		{
+			name:                "should not panic when creating a new array under the mem limit",
+			memLimit:            1000,
+			expectedPanic:       false,
+			shouldForceMemCheck: false,
+		},
+		{
+			name:                "should panic when creating a new array over the mem limit and mem usage check is forced",
+			memLimit:            0,
+			expectedPanic:       true,
+			shouldForceMemCheck: true,
+		},
+		{
+			name:                "should not panic when creating a new array over the mem limit and mem usage check is not forced",
+			memLimit:            0,
+			expectedPanic:       false,
+			shouldForceMemCheck: false,
+		},
+		{
+			name:                "should not panic when creating a new array under the mem limit and mem usage check is forced",
+			memLimit:            1000,
+			expectedPanic:       false,
+			shouldForceMemCheck: true,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			defer func() {
+				r := recover()
+				if tc.expectedPanic && r == nil {
+					t.Error("The code is expected to panic, but it didn't")
+				}
+				if !tc.expectedPanic && r != nil {
+					t.Errorf("The code panicked, but it should not have: %v", r)
+				}
+			}()
+			vm := NewWithContext(context.Background(), tc.shouldForceMemCheck)
+			// Creating a mem usage context so it populates the package variable
+			NewMemUsageContext(100, tc.memLimit, 100, 100, 0.5, nil)
+			vm.newArrayValues([]Value{valueInt(0)})
+		})
+	}
+}

mem_context.go

@@ -67,7 +67,7 @@ type MemUsageContext struct {
 	memoryLimit                    uint64
 }
 
-var memContextMu sync.Mutex
+var memContextMu sync.RWMutex
 var latestMemUsageContext *MemUsageContext
 
 func NewMemUsageContext(
@@ -100,8 +100,8 @@ func NewMemUsageContext(
 }
 
 func newMemUsageContextClone() *MemUsageContext {
-	memContextMu.Lock()
-	defer memContextMu.Unlock()
+	memContextMu.RLock()
+	defer memContextMu.RUnlock()
 	if latestMemUsageContext != nil {
 		return &MemUsageContext{
 			visitTracker:                   visitTracker{objsVisited: make(map[objectImpl]struct{}), stashesVisited: make(map[*stash]struct{})},