Add SlowTestReporter

[ghost]

SlowTestReporter is identical to DefaultReporter, except that at the end of the output it lists your slowest tests to help you track down performance problems:

Running tests:

...............................

Finished tests in 49.962667s, 0.6205 tests/s, 1.0608 assertions/s.

3.314892s WineTest#test: #varietal_group should recognize sparkling blends.
2.123556s WineTest#test: #claim should not blow up claiming unrelated wines.
1.973160s WineTest#test: #claim_family should not blow up claiming unrelated wines without current winery.
1.934369s WineTest#test: #claim_family should claim siblings of specified wine.
1.919199s WineTest#test: #claim_family should claim children of specified wine.

The slow_count option lets you adjust the amount of output:

MiniTest::Reporters.use! MiniTest::Reporters::SlowTestReporter.new(:slow_count => 20)

[kern]

Thanks for this! I combined this with DefaultReporter using the :slow_count option. Pushed in 0.13.0.