Trying to use testdouble in @web/test-runner fails with error about quibble

[superchris]

Description

Trying to use testdouble.js in a test being run by @web/test-runner, a browser automation test runner

Issue

When running, got:

🚧 Browser logs:
SyntaxError: The requested module './quibble.js' does not provide an export named 'default'

[searls]

Interesting. Since quibble is a separate module, I wonder if you're pulling in a bundled/browserify'd build of testdouble.js? Unsure what's happening