rewrite tests

[PalmNeko]

Issue

Written test don't specifications.

Example

The isalpha returns 0 or non-zero value, but you wrote test case that is ft_isslpha(a) == isalpha(a).
This test case does not meet the requirements when a is not an alphabetic character. For example, if ft_isalpha return 8 and isalpha return 3, they are a non-zero value, but they are not equal.

Requirement

• Have to rewrite by tyctest from scratch.
• Don't test that case undefined.