MAINT: Make argument determination in NameValidator more precise.

The function was useing `'u' in case_sensitive` to detect `upper`.
Make that more precise with `case_sensitive.startswith('u').

Raise ValueError if case_sensitive has unrecognized value.

1 files changed, 5 insertions, 1 deletions

diff --git a/numpy/lib/tests/test__iotools.py b/numpy/lib/tests/test__iotools.py
index 92ca1c973..060f815d5 100644
--- a/numpy/lib/tests/test__iotools.py
+++ b/numpy/lib/tests/test__iotools.py
@@ -7,7 +7,8 @@ from datetime import date
 import numpy as np
 from numpy.compat import asbytes, asbytes_nested
 from numpy.testing import (
-    run_module_suite, TestCase, assert_, assert_equal, assert_allclose
+    run_module_suite, TestCase, assert_, assert_equal, assert_allclose,
+    assert_raises
     )
 from numpy.lib._iotools import (
     LineSplitter, NameValidator, StringConverter,
@@ -93,6 +94,9 @@ class TestNameValidator(TestCase):
         test = NameValidator(case_sensitive='lower').validate(names)
         assert_equal(test, ['a', 'a_1', 'b', 'c'])
 
+        # check exceptions
+        assert_raises(ValueError, NameValidator, case_sensitive='foobar')
+
     def test_excludelist(self):
         "Test excludelist"
         names = ['dates', 'data', 'Other Data', 'mask']