Fix would-crash tests if the default allocator used were kNeedFree.

The allocator cannot be destroyed before the Document, otherwise the
Value destructor double frees.

Author: ylavic

test/unittest/documenttest.cpp

@@ -325,6 +325,8 @@ TEST(Document, Swap) {
     EXPECT_TRUE(d1.IsNull());
 
     // reset document, including allocator
+    // so clear o before so that it doesnt contain dangling elements
+    o.Clear();
     Document().Swap(d2);
     EXPECT_TRUE(d2.IsNull());
     EXPECT_NE(&d2.GetAllocator(), &a);

test/unittest/valuetest.cpp

@@ -1078,9 +1078,9 @@ static void TestArray(T& x, Allocator& allocator) {
 }
 
 TEST(Value, Array) {
+    Value::AllocatorType allocator;
     Value x(kArrayType);
     const Value& y = x;
-    Value::AllocatorType allocator;
 
     EXPECT_EQ(kArrayType, x.GetType());
     EXPECT_TRUE(x.IsArray());
@@ -1491,9 +1491,9 @@ static void TestObject(T& x, Allocator& allocator) {
 }
 
 TEST(Value, Object) {
+    Value::AllocatorType allocator;
     Value x(kObjectType);
     const Value& y = x; // const version
-    Value::AllocatorType allocator;
 
     EXPECT_EQ(kObjectType, x.GetType());
     EXPECT_TRUE(x.IsObject());