Add missing unit tests for all form field widgets.

Review Request #9614 — Created Feb. 10, 2018 and submitted — Latest diff uploaded

Information

Djblets
master
64ecd66...

Reviewers

CopyableTextInput and ListEditWidget never had any unit tests, which
meant that issues weren't being caught when working on a port to Django
1.11. ConditionsWidget had tests, but rendering wasn't being tested.

This change adds some tests to ensure that basic rendering functionality
works for these widgets.

Unit tests pass.