Add back some tests for xray. (#2772)

test/array_test.py

@@ -2,7 +2,6 @@ from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
 
-import os
 import numpy as np
 from numpy.testing import assert_equal, assert_almost_equal
 import sys
@@ -75,9 +74,6 @@ class DistributedArrayTest(unittest.TestCase):
                 np.zeros([da.BLOCK_SIZE, da.BLOCK_SIZE])
             ]))
 
-    @unittest.skipIf(
-        os.environ.get("RAY_USE_XRAY") == "1",
-        "This test does not work with xray yet.")
     def testMethods(self):
         for module in [
                 ra.core, ra.random, ra.linalg, da.core, da.random, da.linalg