The term TDD is unfortunate because API design is fundamentally an iterative process, testability being just one (crucial) aspect. For public APIs you simply don't have the luxury of changing the interface after release, so you need to get it right, you need to prove the module's testability by writing and running real tests before release.

More detail on this difficult topic can be found in the "API Design Checklist" section at On Interfaces and APIs. One bullet point from that list clarifies the iterative nature of TDD:

• "Play test" your API from different perspectives: newbie user, expert user, maintenance programmer, support analyst, tester. In the early stages, imagine the perfect interface without worrying about implementation constraints. Design iteratively.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.