1 files changed, 145 insertions, 0 deletions
diff --git a/mfbt/tests/TestWeakPtr.cpp b/mfbt/tests/TestWeakPtr.cpp
new file mode 100644
index 0000000000..0599975a9c
--- /dev/null
+++ b/mfbt/tests/TestWeakPtr.cpp
@@ -0,0 +1,145 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/WeakPtr.h"
+
+using mozilla::SupportsWeakPtr;
+using mozilla::WeakPtr;
+
+static char IamB[] = "B";
+static char IamC[] = "C";
+static char IamD[] = "D";
+
+class B : public SupportsWeakPtr {
+ public:
+  char const* whoAmI() const { return IamB; }
+};
+
+// To have a class C support weak pointers, inherit from SupportsWeakPtr.
+class C : public SupportsWeakPtr {
+ public:
+  int mNum;
+
+  C() : mNum(0) {}
+
+  ~C() {
+    // Setting mNum in the destructor allows us to test against use-after-free
+    // below
+    mNum = 0xDEAD;
+  }
+
+  char const* whoAmI() const { return IamC; }
+
+  void act() {}
+
+  bool isConst() { return false; }
+
+  bool isConst() const { return true; }
+};
+
+// Derived from a class that supports weakptr, but doesn't implement itself
+// To check upcast works as expected
+class D : public B {
+ public:
+  char const* whoAmI() const { return IamD; }
+};
+
+bool isConst(C*) { return false; }
+
+bool isConst(const C*) { return true; }
+
+int main() {
+  C* c1 = new C;
+  MOZ_RELEASE_ASSERT(c1->mNum == 0);
+
+  // Get weak pointers to c1. The first time,
+  // a reference-counted WeakReference object is created that
+  // can live beyond the lifetime of 'c1'. The WeakReference
+  // object will be notified of 'c1's destruction.
+  WeakPtr<C> w1 = c1;
+  // Test a weak pointer for validity before using it.
+  MOZ_RELEASE_ASSERT(w1);
+  MOZ_RELEASE_ASSERT(w1 == c1);
+  w1->mNum = 1;
+  w1->act();
+
+  // Test taking another WeakPtr<C> to c1
+  WeakPtr<C> w2 = c1;
+  MOZ_RELEASE_ASSERT(w2);
+  MOZ_RELEASE_ASSERT(w2 == c1);
+  MOZ_RELEASE_ASSERT(w2 == w1);
+  MOZ_RELEASE_ASSERT(w2->mNum == 1);
+
+  // Test a WeakPtr<const C>
+  WeakPtr<const C> w3const = c1;
+  MOZ_RELEASE_ASSERT(w3const);
+  MOZ_RELEASE_ASSERT(w3const == c1);
+  MOZ_RELEASE_ASSERT(w3const == w1);
+  MOZ_RELEASE_ASSERT(w3const == w2);
+  MOZ_RELEASE_ASSERT(w3const->mNum == 1);
+
+  // Test const-correctness of operator-> and operator T*
+  MOZ_RELEASE_ASSERT(!w1->isConst());
+  MOZ_RELEASE_ASSERT(w3const->isConst());
+  MOZ_RELEASE_ASSERT(!isConst(w1));
+  MOZ_RELEASE_ASSERT(isConst(w3const));
+
+  // Test that when a WeakPtr is destroyed, it does not destroy the object that
+  // it points to, and it does not affect other WeakPtrs pointing to the same
+  // object (e.g. it does not destroy the WeakReference object).
+  {
+    WeakPtr<C> w4local = c1;
+    MOZ_RELEASE_ASSERT(w4local == c1);
+  }
+  // Now w4local has gone out of scope. If that had destroyed c1, then the
+  // following would fail for sure (see C::~C()).
+  MOZ_RELEASE_ASSERT(c1->mNum == 1);
+  // Check that w4local going out of scope hasn't affected other WeakPtr's
+  // pointing to c1
+  MOZ_RELEASE_ASSERT(w1 == c1);
+  MOZ_RELEASE_ASSERT(w2 == c1);
+
+  // Now construct another C object and test changing what object a WeakPtr
+  // points to
+  C* c2 = new C;
+  c2->mNum = 2;
+  MOZ_RELEASE_ASSERT(w2->mNum == 1);  // w2 was pointing to c1
+  w2 = c2;
+  MOZ_RELEASE_ASSERT(w2);
+  MOZ_RELEASE_ASSERT(w2 == c2);
+  MOZ_RELEASE_ASSERT(w2 != c1);
+  MOZ_RELEASE_ASSERT(w2 != w1);
+  MOZ_RELEASE_ASSERT(w2->mNum == 2);
+
+  // Destroying the underlying object clears weak pointers to it.
+  // It should not affect pointers that are not currently pointing to it.
+  delete c1;
+  MOZ_RELEASE_ASSERT(!w1, "Deleting an object should clear WeakPtr's to it.");
+  MOZ_RELEASE_ASSERT(!w3const,
+                     "Deleting an object should clear WeakPtr's to it.");
+  MOZ_RELEASE_ASSERT(w2,
+                     "Deleting an object should not clear WeakPtr that are not "
+                     "pointing to it.");
+
+  delete c2;
+  MOZ_RELEASE_ASSERT(!w2, "Deleting an object should clear WeakPtr's to it.");
+
+  // Check that we correctly upcast to the base class supporting weakptr
+  D* d = new D;
+  WeakPtr<B> db = d;
+
+  // You should be able to use WeakPtr<D> even if it's a base class which
+  // implements SupportsWeakPtr.
+  WeakPtr<D> weakd = d;
+
+  MOZ_RELEASE_ASSERT(db->whoAmI() == IamB);
+  MOZ_RELEASE_ASSERT(weakd.get() == db.get());
+
+  delete d;
+
+  MOZ_RELEASE_ASSERT(!db);
+  MOZ_RELEASE_ASSERT(!weakd);
+}