Levi

This might break TypeScript interfaces, will have to test

> I think this should check for option about `function.length` I think this should be a config option if that's what you're referring to, but I'm not sure what you're...

> anything blocking this?

@kdy1 Regarding this PR, it seems like this feature already exists as you can see here: https://play.swc.rs/?version=1.11.11&code=H4sIAAAAAAAAA0srzUsuyczPU0jTSNRRSNJRSNZUqOZSAIKi1JLSojyFJAVdBSVHDKBkzVXLxZWcn1ecn5Oql5OfrpGmYayjUKGjUKmpaY0mYWigo2Cio2AElAEAT%2BtzyHAAAAA%3D&config=H4sIAAAAAAAAA32US3LbMAxA9zmFR%2Bts20UPkF3PwKFJUKbDj4YAHWsyvnshSrLdGNJOwsOP%2BH2%2FHQ7dGU335%2FDNn%2Fwz6IJQ7v8swTGRvrKkAxM1muIH6t5XesYJOR0Qmug2k4506YGaFf5a1LuQM8KqvsiiT96NzwFNjkMBxCcZS9lfjZAI%2F7dfWMlfE6BSn%2BXHnAPotEOURuUTQQ9FcmxyCHpAUBddBC9Tprp4zFKICVYCq4aSB5En68nnxDFfqQVtlckWBOQLGPIXkMw4Fpsl5OcJ72nYwrH2fWvyD2u46FA1CTHh2lrC2QpeT9kjKVeTVMIZbtRghktxf1p6pwpQLenV7px92ujJJwBXIGjEpCNIfpuG43nahrumPjmeWRoFzgMuPTNBz1VV3juhtFNpoJCX2lnAVgNTaY2UzoI36ofeggLneFgE1%2FjlyZykoDQOkJ0AuMHaSWM1A3Vfww0%2BbcQO%2FuBXkjxhi0bUdNqmOMZjDjsBItAp2x0FbgXlbVz4TFyHbV6TBR4NsKJKxQZerwBvAGUV2rV8mQ3eD%2Fao%2BpCPjzuxKNzuVzjq1D8Wfj7Eb4tCF7OtDS4nfurvfJh%2Fdw%2Bl9QyvGXQe%2F66GLebtH%2F2BV4AtBgAA The option is `keep_fargs` in the compress module. Apparently it was added 4...

Regarding `function.length` for anyone wondering: ```js function f(x, y) {} console.log(f.length); // 2 ``` I don't think it's worth adding a check for this in (assuming it doesn't exist already)....

Closed because already implemented (`keep_fargs` option in compress) https://swc.rs/docs/configuration/minification

Several swc tests rely on the parsed test code being a module due to their visitors, going to have to fix these. The good news is that this will fix...

I will probably clean up the internal API a bit because I think it's a bit messy, but essentially how testing works now: - Current `test` implementations will continue to...

Not sure what we think of the internal api, `test!(module, ...)`, `test!(script, ...)`, `apply_module_transform` etc.

@kdy1 can you un-merge? Not finished yet. Forgot to mark as draft