test: convert more tests to ESM

[rossiam]

Convert a few more unit tests to ESM.

Checklist

• [x] I have read the CONTRIBUTING document
• [x] My code follows the code style of this project (npm run lint produces no warnings/errors)

[changeset-bot[bot]]

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Latest commit: e5f72e165c010847f6cd4c3b9fb000a4b1d20c53

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