Remove unused imports from docs tests

[Harsh1s]

Cleaned all the unused imports, which can be confusing to clients and developers.

Part of #4570

[CLAassistant]

All committers have signed the CLA.

[robertbastian]

Thanks! Please also update the job in tests.toml with the arguments you used so that we don't backslide.

[sffc]

Thanks for doing this! Two things:

1. Please check the test-docs CI and make sure all the docs tests are still passing.
2. As @robertbastian suggested, please modify the job to run with the correct flags to prevent backsliding. You can set the flags in [tasks.test-docs] in tools/make/tests.toml here:

   icu4x/tools/make/tests.toml

   Line 49 in 4242dfb

   [tasks.test-docs]

[sffc]

^

[Harsh1s]

I have fixed the failing test now, it happened cuz I removed a legit import accidently.

Now about the test.toml arguements, from my research, I found out that rustdoc does not currently warn about unused imports. It’s a known limitation of rustdoc. So since there are no warnings generated, it is kind of difficult to prevent backsliding as you guys adviced. I'm still trying a few things but just wanted to keep you in the loop.

[Harsh1s]

Here's an update of what I found:
"You can show warnings in doctests by running rustdoc --test --test-args=--show-output" is what the rust documentation says. So I went ahead and ran RUSTFLAGS="-D warnings" RUSTDOCFLAGS="--test-args --show-output" cargo test --all-features --doc --no-fail-fast on the command line. Unfortunately, there was not a single warning concerning unused imports. This makes it kind of complicated as no warnings mean nothing to abort or fix automatically.

@robertbastian I hope I'm not doing something absolutely stupid, would like to hear your advice on this.

[robertbastian]

I've looked into this and couldn't find a way to do this either. There's an open issue for this (rust-lang/rust#56232), but no workaround afaict. Let's merge the manual fixes for now.

Edit: please fix broken tests

[Harsh1s]

I've looked into this and couldn't find a way to do this either. There's an open issue for this (rust-lang/rust#56232), but no workaround afaict. Let's merge the manual fixes for now.

Edit: please fix broken tests

Yeah unfortunately it was a wild goose chase :(
On the bright side though, manually removing them helped me understand the project more. Hope to make good contributions moving forward!

P.S. I've fixed the broken tests, @robertbastian thanks for your help with the issue!