diff -r 000000000000 -r 6474c204b198 testing/mozbase/mozdevice/sut_tests/test_fileExists.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/testing/mozbase/mozdevice/sut_tests/test_fileExists.py	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,37 @@
+# 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/.
+
+import tempfile
+import posixpath
+
+from dmunit import DeviceManagerTestCase
+
+class FileExistsTestCase(DeviceManagerTestCase):
+    """This tests the "fileExists" command.
+    """
+
+    def testOnRoot(self):
+        self.assertTrue(self.dm.fileExists('/'))
+
+    def testOnNonexistent(self):
+        self.assertFalse(self.dm.fileExists('/doesNotExist'))
+
+    def testOnRegularFile(self):
+        remote_path = posixpath.join(self.dm.getDeviceRoot(), 'testFile')
+        self.assertFalse(self.dm.fileExists(remote_path))
+        with tempfile.NamedTemporaryFile() as f:
+            self.dm.pushFile(f.name, remote_path)
+        self.assertTrue(self.dm.fileExists(remote_path))
+        self.dm.removeFile(remote_path)
+
+    def testOnDirectory(self):
+        remote_path = posixpath.join(self.dm.getDeviceRoot(), 'testDir')
+        remote_path_file = posixpath.join(remote_path, 'testFile')
+        self.assertFalse(self.dm.fileExists(remote_path))
+        with tempfile.NamedTemporaryFile() as f:
+            self.dm.pushFile(f.name, remote_path_file)
+        self.assertTrue(self.dm.fileExists(remote_path))
+        self.dm.removeFile(remote_path_file)
+        self.dm.removeDir(remote_path)
+