Support Dark Tests

[StachuDotNet]

Users, including myself, have hacked "tests" into Dark through various means. We should support testing as a fully-fledged feature set.

[StachuDotNet]

This has been my pattern so far:

[StachuDotNet]

I imagine some future where I have a table view of tests, where I edit "name", "expected", and "actual" values of tests really quickly by tabbing through a 3-column table.

tab, type test name, tab, type expected value (e.g. ), tab, type actual (e.g. htmlTagHtml [] [])

[StachuDotNet]

Feedback from @edman

would be cool to have integration between traces and tests
e.g. you double click the little white trace ball to add the actual/expected entry into the test table for this function
e.g. right-click > run all traces to ensure a refactor does not change behavior

another thing I would love to see is some type of property testing or test input generation