there are things you need to test for to get test coverage

Function coverage – has each function been tested?
Statement coverage – has each node in the program been executed?
Decision coverage – has each edge in the program been executed? (IF and CASE
statements)
Condition coverage – has each Boolean sub-expression evaluated both to true and false?
Parameter value coverage – Has the most common parameter values been tested?
Loop coverage – Has every loop executed zero times, once, and more than once?
Boundary testing – Test for range boundaries. If an integer variable can be between one and
ten, then test the following values: 0, 1, 2, 9, 10, and 11.

I am so smart I can implement this without test driving it

I don’t know how to write tests

This is a really small change, no need for tests

This cannot break anything

I’m in a rush, no time for TDD

I wanted to write tests, but I didn’t :-)

It’d be too hard to test this mess

TDD’s not a silver bullet. With or without it, doesn’t matter

I’m prototyping

I’ll do the real work, then you can play around with your tests