Added exception and unittest for dist_mat_to_vec of analysis/psa.py (…

…Part of MDAnalysis#597)

package/MDAnalysis/analysis/psa.py

@@ -576,7 +576,8 @@ def dist_mat_to_vec(N, i, j):
     """
 
     if not (isinstance(N, numbers.Integral) or isinstance(i, numbers.Integral) or isinstance(j, numbers.Integral)):
-        raise ValueError("N, i, j all must be of type int")
+        err_str = "N, i, j all must be of type int"
+        raise ValueError(err_str)
 
     if i < 0 or j < 0 or N < 2:
         error_str = "Matrix indices are invalid; i and j must be greater than 0 and N must be greater the 2"

testsuite/MDAnalysisTests/analysis/test_psa.py

@@ -103,6 +103,16 @@ def test_dist_mat_to_vec_i_greater_j(self):
         err_msg = "dist_mat_to_vec function returning wrong values"
         assert_equal(PSA.dist_mat_to_vec(5, 4, 3), 9, err_msg)
 
+    def test_dist_mat_to_vec_input_numpy_integer_32(self):
+        """Test whether inputs are supported as numpy integers rather than normal Integers"""
+        err_msg = "dist_mat_to_vec function returning wrong values"
+        assert_equal(PSA.dist_mat_to_vec(np.int32(5), np.int32(3), np.int32(4)), err_msg)
+
+    def test_dist_mat_to_vec_input_numpy_integer_16(self):
+        """Test whether inputs are supported as numpy integers rather than normal Integers"""
+        err_msg = "dist_mat_to_vec function returning wrong values"
+        assert_equal(PSA.dist_mat_to_vec(np.int16(5), np.int16(3), np.int16(4)), err_msg)
+
 class TestPSAExceptions(TestCase):
     '''Tests for exceptions that should be raised
     or caught by code in the psa module.'''
@@ -171,6 +181,7 @@ def test_dist_mat_to_vec_func_bad_integers(self):
         with self.assertRaises(ValueError):
             PSA.dist_mat_to_vec(5, float(6), 7)
 
+
 class _BaseHausdorffDistance(TestCase):
     '''Base Class setup and unit tests
     for various Hausdorff distance