a11y addon tests don't run on story load or change

[mattrothenberg]

Describe the bug
When using the a11y addon, I expect the tests for a particular story to run automatically on initial page load, and then on any subsequent story change.

I am using the global decorator, not individual decorators per components.

Currently, I have to manually press Rerun test in order for the tests to run at all.

To Reproduce
Steps to reproduce the behavior:

1. Spin up Storybook
2. Visit http://localhost:9001
3. Observe that there are no violations OR passes
4. Press Rerun Test
5. See that there are now violations/passes.

Expected behavior
I expect the tests to be run automatically when a story loads.

System:

• OS: 10.14.3
• Device: 2018 MBP
• Browser: Chrome 72.0.3626.109
• Framework: React
• Addons: a11y
• Version: 4.2.0-alpha.10

Additional context
I'm not using the latest version in the 4 series, as per this issue: #5078

[mattrothenberg]

FWIW, this is now working beautifully after updating to latest release candidate ❤️