Code correctness, and testing strategies

[Paul Rubin]

Duncan Booth <duncan.booth at invalid.invalid> writes:
> I made the mistake at one point when I was trying to sell the concept of 
> TDD telling the people I was trying to persuade that by writing the tests 
> up front it influences the design of the code. I felt the room go cold: 
> they said the customer has to sign off the design before we start coding, 
> and once they've signed it off we can't change anything.

Usually the customer signs off on a functional specification but that
has nothing to do with the coding style.  Jacob makes a very good
point that TDD influences coding style, for example by giving a strong
motivation to separate computational code from I/O.  But that is
independent of the external behavior that the customer cares about.