Let the test folder add its own files

[andiwand]

A colleague suggested we generate the Xcode project with xcodegen instead of committing it. I looked into it and the trade doesn't work for us — Dependabot updates our Swift packages by editing project.pbxproj directly, Package.resolved lives inside the .xcodeproj so the pins would go with it, and xcodegen 2.41 doesn't know about synchronized folders, which is the mechanism that already keeps our project file quiet.

What was left of the churn was one narrow thing, and this fixes that instead.

The app folders have been synchronized groups for a while, so adding a source file takes no project edit. The test folder was still a hand-written list, and every test or fixture we added cost four lines of made-up object ids — 8eba37e, c353ccc, 589f4f7, d1956df are all that and nothing else. It's a synchronized group now too.

Two things had to move out of the folder first, since a synchronized group copies whatever is left in it into the bundle:

• fixtures/make-fixtures.py → scripts/make-test-fixtures.py. It would otherwise be bundled as a resource, along with any __pycache__ left behind by running it.
• Info.plist is gone, replaced by GENERATE_INFOPLIST_FILE. It held nothing but build-setting placeholders, and dropping it means the folder needs no membership exception.

Checked:

• The full suite passes on the simulator, fixture-dependent tests included, and the built .xctest holds exactly the six sample documents it held before — no strays, and the generated Info.plist carries the same identity keys the stub did.
• A throwaway test file compiled and ran with no change to project.pbxproj, which is the whole point.
• The generator still writes correct fixtures from its new home: the regenerated test.pdf is byte-identical, and the zips differ only in timestamps.

README updated — it documented "three folders, each a synchronized group", which is now four.

🤖 Generated with Claude Code