AK: Fix ref leak in NonnullRefPtr::operator=(T&).

We would leak a ref when assigning a T& to a NonnullRefPtr that already
contains that same T.

2 files changed, 40 insertions, 1 deletions

diff --git a/AK/Tests/Makefile b/AK/Tests/Makefile
index 3847c4834e..f1a28322a9 100644
--- a/AK/Tests/Makefile
+++ b/AK/Tests/Makefile
@@ -1,4 +1,4 @@
-PROGRAMS = TestString TestQueue TestVector TestHashMap TestJSON TestWeakPtr
+PROGRAMS = TestString TestQueue TestVector TestHashMap TestJSON TestWeakPtr TestNonnullRefPtr
 
 CXXFLAGS = -std=c++17 -Wall -Wextra -ggdb3 -O2 -I../ -I../../
 
@@ -42,6 +42,9 @@ TestJSON: TestJSON.o $(SHARED_TEST_OBJS)
 TestWeakPtr: TestWeakPtr.o $(SHARED_TEST_OBJS) 
 	$(PRE_CXX) $(CXX) $(CXXFLAGS) -o $@ TestWeakPtr.o $(SHARED_TEST_OBJS)
 
+TestNonnullRefPtr: TestNonnullRefPtr.o $(SHARED_TEST_OBJS)
+	$(PRE_CXX) $(CXX) $(CXXFLAGS) -o $@ TestNonnullRefPtr.o $(SHARED_TEST_OBJS)
+
 clean:
 	rm -f $(SHARED_TEST_OBJS)
 	rm -f $(PROGRAMS)
diff --git a/AK/Tests/TestNonnullRefPtr.cpp b/AK/Tests/TestNonnullRefPtr.cpp
new file mode 100644
index 0000000000..9012206586
--- /dev/null
+++ b/AK/Tests/TestNonnullRefPtr.cpp
@@ -0,0 +1,36 @@
+#include <AK/TestSuite.h>
+
+#include <AK/NonnullRefPtr.h>
+#include <AK/AKString.h>
+
+struct Object : public RefCounted<Object> {
+    int x;
+};
+
+TEST_CASE(basics)
+{
+    auto object = adopt(*new Object);
+    EXPECT(object.ptr() != nullptr);
+    EXPECT_EQ(object->ref_count(), 1);
+    object->ref();
+    EXPECT_EQ(object->ref_count(), 2);
+    object->deref();
+    EXPECT_EQ(object->ref_count(), 1);
+
+    {
+        NonnullRefPtr another = object;
+        EXPECT_EQ(object->ref_count(), 2);
+    }
+
+    EXPECT_EQ(object->ref_count(), 1);
+}
+
+TEST_CASE(assign_reference)
+{
+    auto object = adopt(*new Object);
+    EXPECT_EQ(object->ref_count(), 1);
+    object = *object;
+    EXPECT_EQ(object->ref_count(), 1);
+}
+
+TEST_MAIN(String)