Duplicate dependency problem during dependency transition of v1 to v2 addon

[NullVoxPopuli]

When upgrading a special-ember-addon from a v1 addon to v2 addon upgrade (and both existing in the same project) -- there is an issue, an error: "test waiters can't be found"

if both loaded at the same time, test-waiters should still work appropriately, due to all the settled state info living on globalThis

Repro: https://github.com/NullVoxPopuli/repro-vX-v2-vY-v1-addon-coexistence

Also repro:

• create new ember project (does not include test-waiters)
• add test-waiters (v4)
• start app, visit /tests

I suspect this is the same issue with @ember/string?

The situation (rn)

• @ember/test-helpers -> @ember/test-waiters@v3
• app -> @ember/test-waiters@v4

---

A possible work-around (requires a bit of luck (no v1 addens without auto-import)) if folks need it is to set an overrides for @ember/test-waiters. This would also make your install times a bit faster in case you accidentally had many copies.
(tho note v4 is a breaking change, so check the changelog in test-waiters)

[NullVoxPopuli]

Problem does not exist under vite: https://github.com/NullVoxPopuli/repro-vX-v2-vY-v1-addon-coexistence/tree/vite

[NullVoxPopuli]

Problem does not exist under embroidedr-3-webpack-4: https://github.com/NullVoxPopuli/repro-vX-v2-vY-v1-addon-coexistence/tree/embroider-3-webpack-4

[mansona]

Was this fixed in #667 ?

[NullVoxPopuli]

I haven't checked 🙈