Todo list for the unit test library

[gavinfielder]

I'll keep this as a static issue just to keep track of all the to-do items for unit_tests.c.

Test Naming

• Generally improve consistency
• The new2019 block of tests from cclaude could be better integrated into the naming conventions.

Types of tests to add

• Add test functionality for %n (high priority) - requires adding functionality to PFT code.
• Add more * tests that combine with other flags and specifiers. (high priority)
• Add %s tests with long strings (medium priority)
• Add tests for z, t, and j size modifiers (low priority)
• Add tests for %a (low priority)
• Add tests for ' (thousands separator flag) (low priority)

Other

Specific tests to add