Call the assert_string_equal() function to compare a string with itself. This test, of course, should pass:

print("Pass", np.testing.assert_string_equal("NumPy", "NumPy"))

The test passes:

Pass None

Call the assert_string_equal() function to compare a string with another string with the same letters, but different casing. This test should throw an exception:

print("Fail", np.testing.assert_string_equal("NumPy", "Numpy"))

The test raises an error:

Fail
Traceback (most recent call last):
  …
    raise AssertionError(msg)
AssertionError: Differences in strings:
- NumPy?    ^
+ Numpy?    ^