revert moving of ram filesystem test
diff --git a/tensorflow/core/platform/BUILD b/tensorflow/core/platform/BUILD
index 28427a8..0c63a38 100644
--- a/tensorflow/core/platform/BUILD
+++ b/tensorflow/core/platform/BUILD
@@ -426,6 +426,15 @@
     ],
 )
 
+py_test(
+    name = "ram_file_system_test",
+    srcs = ["ram_file_system_test.py"],
+    python_version = "PY3",
+    deps = [
+        "//tensorflow:tensorflow_py",
+    ],
+)
+
 cc_library(
     name = "numbers",
     srcs = ["numbers.cc"],
diff --git a/tensorflow/python/platform/ram_file_system_test.py b/tensorflow/core/platform/ram_file_system_test.py
similarity index 92%
rename from tensorflow/python/platform/ram_file_system_test.py
rename to tensorflow/core/platform/ram_file_system_test.py
index ab21460..125d871 100644
--- a/tensorflow/python/platform/ram_file_system_test.py
+++ b/tensorflow/core/platform/ram_file_system_test.py
@@ -155,24 +155,6 @@
     loaded = saved_model.load('ram://my_module')
     self.assertAllEqual(loaded.foo(), [1])
 
-  def test_join(self):
-    expected = 'ram://exists/a/b/c.txt'
-    self.assertEqual(
-      file_io.join('ram://', 'exists', 'a', 'b', 'c.txt'),
-      expected
-    )
-    self.assertEqual(
-      file_io.join('ram://exists', 'a', 'b', 'c.txt'),
-      expected
-    )
-    self.assertEqual(
-      file_io.join('ram://', 'exists/a', 'b', 'c.txt'),
-      expected
-    )
-    self.assertEqual(
-      file_io.join('ram://', 'exists', 'a', 'b/c.txt'),
-      expected
-    )
 
 if __name__ == '__main__':
   test.main()
diff --git a/tensorflow/python/platform/BUILD b/tensorflow/python/platform/BUILD
index 54ada1f..19653f6 100644
--- a/tensorflow/python/platform/BUILD
+++ b/tensorflow/python/platform/BUILD
@@ -238,16 +238,6 @@
     ],
 )
 
-tf_py_test(
-    name = "ram_file_system_test",
-    size = "small",
-    srcs = ["ram_file_system_test.py"],
-    python_version = "PY3",
-    deps = [
-        "//tensorflow:tensorflow_py",
-    ],
-)
-
 pybind_extension(
     name = "_pywrap_tf2",
     srcs = ["enable_tf2.cc"],