Add smoke test for sklearnex

sklearnex was added in #1135

http://227237481

Author: rosbo

tests/test_sklearnex.py

@@ -0,0 +1,15 @@
+import unittest
+
+import numpy as np
+
+from sklearn.cluster import DBSCAN
+
+class TestSklearnex(unittest.TestCase):
+    def test_dbscan(self):
+        from sklearnex import patch_sklearn
+        patch_sklearn()
+        X = np.array([[1., 2.], [2., 2.], [2., 3.],
+            [8., 7.], [8., 8.], [25., 80.]], dtype=np.float32)
+
+        clustering = DBSCAN(eps=3, min_samples=2).fit(X)
+        np.testing.assert_array_equal(np.array([0, 0, 0, 1, 1, -1]), clustering.labels_)