Splits up unit test into 5 sub tests.

Author: chaburkland

test/test_util.py

@@ -301,9 +301,7 @@ def test_isna_element_false(self) -> None:
         self.assertFalse(isna_element(datetime.date(2020, 12, 31)))
         self.assertFalse(isna_element(False))
 
-    def test_dtype_from_element(self) -> None:
-        NT = collections.namedtuple('NT', tuple('abc'))
-
+    def test_dtype_from_element_core_dtypes(self) -> None:
         dtypes = [
                 np.longlong,
                 np.int_,
@@ -327,6 +325,7 @@ def test_dtype_from_element(self) -> None:
         for dtype in dtypes:
             self.assertEqual(dtype, dtype_from_element(dtype()))
 
+    def test_dtype_from_element_str_and_misc_dtypes(self) -> None:
         dtype_obj_pairs = [
                 (np.dtype('<U1'), np.str_('1')),
                 (np.dtype('<U1'), np.unicode_('1')),
@@ -339,6 +338,9 @@ def test_dtype_from_element(self) -> None:
         for dtype, obj in dtype_obj_pairs:
             self.assertEqual(dtype, dtype_from_element(obj))
 
+    def test_dtype_from_element_obj_dtypes(self) -> None:
+        NT = collections.namedtuple('NT', tuple('abc'))
+
         dtype_obj_pairs = [
                 (np.int_, 12),
                 (np.float_, 12.0),
@@ -354,12 +356,14 @@ def test_dtype_from_element(self) -> None:
         for dtype, obj in dtype_obj_pairs:
             self.assertEqual(dtype, dtype_from_element(obj))
 
+    def test_dtype_from_element_time_dtypes(self) -> None:
         # Datetime & Timedelta
         for precision in ['ns', 'us', 'ms', 's', 'm', 'h', 'D', 'M', 'Y']:
             for kind, ctor in (('m', np.timedelta64), ('M', np.datetime64)):
                 obj = ctor(12, precision)
                 self.assertEqual(np.dtype(f'<{kind}8[{precision}]'), dtype_from_element(obj))
 
+    def test_dtype_from_element_str_and_bytes_dtypes(self) -> None:
         for size in (1, 8, 16, 32, 64, 128, 256, 512):
             self.assertEqual(np.dtype(f'|S{size}'), dtype_from_element(bytes(size)))
             self.assertEqual(np.dtype(f'<U{size}'), dtype_from_element('x' * size))