Ref #671

Rationale for this change

All of the tests in test_functions.py are overloaded - representing many more than one test case.

What changes are included in this PR?

This cleans up test_array_functions, which becomes 62 different test cases.

test_array_functions now has 56 passing test cases and 1 expected failure (array_slice being the expected failure Ref #670).

test_array_function_flatten was broken out as a single test because it was an outlier in terms of test-input.

test_array_function_obj_tests had a different set of asserts, so was broken out for 4 test cases.