diff -r 000000000000 -r 6474c204b198 gfx/tests/gtest/gfxWordCacheTest.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/tests/gtest/gfxWordCacheTest.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,133 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * 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 "gtest/gtest.h"
+
+#include "nsCOMPtr.h"
+#include "nsTArray.h"
+#include "nsString.h"
+#include "nsDependentString.h"
+
+#include "prinrval.h"
+
+#include "gfxContext.h"
+#include "gfxFont.h"
+#include "gfxPlatform.h"
+
+#include "gfxFontTest.h"
+#include "mozilla/Attributes.h"
+
+class FrameTextRunCache;
+
+static FrameTextRunCache *gTextRuns = nullptr;
+
+/*
+ * Cache textruns and expire them after 3*10 seconds of no use.
+ */
+class FrameTextRunCache MOZ_FINAL : public nsExpirationTracker<gfxTextRun,3> {
+public:
+ enum { TIMEOUT_SECONDS = 10 };
+ FrameTextRunCache()
+     : nsExpirationTracker<gfxTextRun,3>(TIMEOUT_SECONDS*1000) {}
+ ~FrameTextRunCache() {
+   AgeAllGenerations();
+ }
+
+ void RemoveFromCache(gfxTextRun* aTextRun) {
+   if (aTextRun->GetExpirationState()->IsTracked()) {
+     RemoveObject(aTextRun);
+   }
+ }
+
+ // This gets called when the timeout has expired on a gfxTextRun
+ virtual void NotifyExpired(gfxTextRun* aTextRun) {
+   RemoveFromCache(aTextRun);
+   delete aTextRun;
+ }
+};
+
+static gfxTextRun *
+MakeTextRun(const char16_t *aText, uint32_t aLength,
+           gfxFontGroup *aFontGroup, const gfxFontGroup::Parameters* aParams,
+           uint32_t aFlags)
+{
+   nsAutoPtr<gfxTextRun> textRun;
+   if (aLength == 0) {
+       abort();
+       //textRun = aFontGroup->MakeEmptyTextRun(aParams, aFlags);
+   } else if (aLength == 1 && aText[0] == ' ') {
+       abort();
+       //textRun = aFontGroup->MakeSpaceTextRun(aParams, aFlags);
+   } else {
+       textRun = aFontGroup->MakeTextRun(aText, aLength, aParams, aFlags);
+   }
+   if (!textRun)
+       return nullptr;
+   nsresult rv = gTextRuns->AddObject(textRun);
+   if (NS_FAILED(rv)) {
+       gTextRuns->RemoveFromCache(textRun);
+       return nullptr;
+   }
+   return textRun.forget();
+}
+
+static already_AddRefed<gfxContext>
+MakeContext ()
+{
+   const int size = 200;
+
+   nsRefPtr<gfxASurface> surface;
+
+   surface = gfxPlatform::GetPlatform()->
+       CreateOffscreenSurface(IntSize(size, size),
+                              gfxASurface::ContentFromFormat(gfxImageFormat::RGB24));
+   nsRefPtr<gfxContext> ctx = new gfxContext(surface);
+   return ctx.forget();
+}
+
+TEST(Gfx, WordCache) {
+   gTextRuns = new FrameTextRunCache();
+
+   nsRefPtr<gfxContext> ctx = MakeContext();
+   {
+       gfxFontStyle style (mozilla::gfx::FontStyle::NORMAL,
+                           139,
+                           10.0,
+                           0,
+                           NS_NewPermanentAtom(NS_LITERAL_STRING("en")),
+                           0.0,
+                           false, false,
+                           NS_LITERAL_STRING(""));
+
+       nsRefPtr<gfxFontGroup> fontGroup =
+           gfxPlatform::GetPlatform()->CreateFontGroup(NS_LITERAL_STRING("Geneva, MS Sans Serif, Helvetica,serif"), &style, nullptr);
+
+       gfxTextRunFactory::Parameters params = {
+           ctx, nullptr, nullptr, nullptr, 0, 60
+       };
+
+       uint32_t flags = gfxTextRunFactory::TEXT_IS_PERSISTENT;
+
+       // First load an Arabic word into the cache
+       const char cString[] = "\xd8\xaa\xd9\x85";
+       nsDependentCString cStr(cString);
+       NS_ConvertUTF8toUTF16 str(cStr);
+       gfxTextRun *tr = MakeTextRun(str.get(), str.Length(), fontGroup, &params, flags);
+       tr->GetAdvanceWidth(0, str.Length(), nullptr);
+
+       // Now try to trigger an assertion with a word cache bug. The first
+       // word is in the cache so it gets added to the new textrun directly.
+       // The second word is not in the cache 
+       const char cString2[] = "\xd8\xaa\xd9\x85\n\xd8\xaa\xd8\x85 ";
+       nsDependentCString cStr2(cString2);
+       NS_ConvertUTF8toUTF16 str2(cStr2);
+       gfxTextRun *tr2 = MakeTextRun(str2.get(), str2.Length(), fontGroup, &params, flags);
+       tr2->GetAdvanceWidth(0, str2.Length(), nullptr);
+   }
+
+   delete gTextRuns;
+   gTextRuns = nullptr;
+
+}