diff -r 000000000000 -r 6474c204b198 toolkit/components/osfile/tests/xpcshell/test_compression.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/components/osfile/tests/xpcshell/test_compression.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,52 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+Components.utils.import("resource://gre/modules/osfile.jsm");
+
+function run_test() {
+  do_test_pending();
+  run_next_test();
+}
+
+add_task(function test_compress_lz4() {
+  let path = OS.Path.join(OS.Constants.Path.tmpDir, "compression.lz");
+  let array = new Uint8Array(1024);
+  for (let i = 0; i < array.byteLength; ++i) {
+    array[i] = i;
+  }
+
+  do_print("Writing data with lz4 compression");
+  let bytes = yield OS.File.writeAtomic(path, array, { compression: "lz4" });
+  do_print("Compressed " + array.byteLength + " bytes into " + bytes);
+
+  do_print("Reading back with lz4 decompression");
+  let decompressed = yield OS.File.read(path, { compression: "lz4" });
+  do_print("Decompressed into " + decompressed.byteLength + " bytes");
+  do_check_eq(Array.prototype.join.call(array), Array.prototype.join.call(decompressed));
+});
+
+add_task(function test_uncompressed() {
+  do_print("Writing data without compression");
+  let path = OS.Path.join(OS.Constants.Path.tmpDir, "no_compression.tmp");
+  let array = new Uint8Array(1024);
+  for (let i = 0; i < array.byteLength; ++i) {
+    array[i] = i;
+  }
+  let bytes = yield OS.File.writeAtomic(path, array); // No compression
+
+  let exn;
+  // Force decompression, reading should fail
+  try {
+    yield OS.File.read(path, { compression: "lz4" });
+  } catch (ex) {
+    exn = ex;
+  }
+  do_check_true(!!exn);
+  do_check_true(exn.message.indexOf("Invalid header") != -1);
+});
+
+add_task(function() {
+  do_test_finished();
+});