Don't try to compile examples if they have #![ cfg(not( target_arch = "wasm32" )) ]

[najamelan]

🐛 Bug description

When supporting both wasm and other targets in a crate, I found it not obvious how to deal with tests and examples. It turned out that adding #![ cfg(not( target_arch = "wasm32" )) ] to files for integration tests that aren't wasm keeps wasm-pack test from trying to run them.

However, when you have an example in the examples folder that isn't wasm, wasm-pack test will still try to compile it, and even when putting a target based gate at the top. The result is that #![ cfg(not( target_arch = "wasm32" )) ] on top of the file will break tests because:

error[E0601]: `main` function not found in crate `localpool`

I haven't found a reasonable workaround...

🤔 Expected Behavior

Have a convenient way of supporting both wasm and non wasm targets in the same crate.
Document how to deal with tests and examples in this regard (in the book)

👟 Steps to reproduce

Create an example in examples folder that isn't meant for wasm target. Run unit tests with wasm-pack test

🌍 Your environment

linux
wasm-pack version: wasm-pack 0.7.0
rustc version: rustc 1.37.0-nightly (02564de47 2019-06-10)

[najamelan]

Ok, the workaround I found is to put a gate on every single command that is toplevel and to add a dummy main at the bottom:

#[ cfg( target_arch = "wasm32" ) ]
//
fn main(){}

It's pretty ugly, especially for examples which are a form of documentation.

[najamelan]

I have since filed an issue with cargo, as I think cargo test should not consider these examples on the wrong target. rust-lang/cargo#7233