diff -r 000000000000 -r 6474c204b198 xpcom/tests/TestStorageStream.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/tests/TestStorageStream.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,110 @@
+/* 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 <stdlib.h>
+#include "nsIStorageStream.h"
+#include "nsIInputStream.h"
+#include "nsIOutputStream.h"
+#include "nsCOMPtr.h"
+
+int main()
+{
+  char kData[4096];
+  memset(kData, 0, sizeof(kData));
+
+  nsresult rv;
+  nsCOMPtr<nsIStorageStream> stor;
+
+  rv = NS_NewStorageStream(4096, UINT32_MAX, getter_AddRefs(stor));
+  if (NS_FAILED(rv))
+    return -1;
+
+  nsCOMPtr<nsIOutputStream> out;
+  rv = stor->GetOutputStream(0, getter_AddRefs(out));
+  if (NS_FAILED(rv))
+    return -1;
+
+  uint32_t n;
+
+  rv = out->Write(kData, sizeof(kData), &n);
+  if (NS_FAILED(rv))
+    return -1;
+
+  rv = out->Write(kData, sizeof(kData), &n);
+  if (NS_FAILED(rv))
+    return -1;
+
+  rv = out->Close();
+  if (NS_FAILED(rv))
+    return -1;
+
+  out = nullptr;
+  
+  nsCOMPtr<nsIInputStream> in;
+  rv = stor->NewInputStream(0, getter_AddRefs(in));
+  if (NS_FAILED(rv))
+    return -1;
+
+  char buf[4096];
+
+  // consume contents of input stream
+  do {
+    rv = in->Read(buf, sizeof(buf), &n);
+    if (NS_FAILED(rv))
+      return -1;
+  } while (n != 0);
+
+  rv = in->Close();
+  if (NS_FAILED(rv))
+    return -1;
+  in = nullptr;
+
+  // now, write 3 more full 4k segments + 11 bytes, starting at 8192
+  // total written equals 20491 bytes
+
+  rv = stor->GetOutputStream(8192, getter_AddRefs(out));
+  if (NS_FAILED(rv))
+    return -1;
+
+  rv = out->Write(kData, sizeof(kData), &n);
+  if (NS_FAILED(rv))
+    return -1;
+
+  rv = out->Write(kData, sizeof(kData), &n);
+  if (NS_FAILED(rv))
+    return -1;
+
+  rv = out->Write(kData, sizeof(kData), &n);
+  if (NS_FAILED(rv))
+    return -1;
+
+  rv = out->Write(kData, 11, &n);
+  if (NS_FAILED(rv))
+    return -1;
+
+  rv = out->Close();
+  if (NS_FAILED(rv))
+    return -1;
+
+  out = nullptr;
+
+  // now, read all
+  rv = stor->NewInputStream(0, getter_AddRefs(in));
+  if (NS_FAILED(rv))
+    return -1;
+
+  // consume contents of input stream
+  do {
+    rv = in->Read(buf, sizeof(buf), &n);
+    if (NS_FAILED(rv))
+      return -1;
+  } while (n != 0);
+
+  rv = in->Close();
+  if (NS_FAILED(rv))
+    return -1;
+  in = nullptr;
+
+  return 0;
+}