wasm-bindgen-macro

Implementation of the #[wasm_bindgen] attribute. See the wasm-bindgen documentation for more information about what this macro does.

Testing

Testing of this macro is done through "ui tests" in the ui-tests subdirectory of this crate. Each Rust file in this folder is compiled with the wasm_bindgen crate, and the *.stderr file sitting next to it is the asserted output of the compiler. If the output matches, the test passes, and if the output doesn't match the test fails. Note that for these tests it is also considered a failure if a test actually compiles successfully.

There is also a pass-tests subdirectory for the opposite assertion: each Rust file there must compile successfully, with no *.stderr file. Use it to pin that a supported shape keeps working, especially one whose generated code is easy to break (for example the generic import paths, where a mistake in codegen surfaces as a rustc error against code the user never wrote). Note that a #[wasm_bindgen(experimental_generic_mono)] import only generates code when it is actually instantiated, so a pass test needs a call site, not just the declaration.

Both directories are registered in tests/ui.rs.

To add a test:

• Create ui-tests/my-awesome-test.rs

• Write an invalid #[wasm_bindgen] invocation, testing the error you're generating

• Execute cargo test -p wasm-bindgen-macro --test ui, the test will fail

• From within the ui-tests folder, execute ./update-all-references.sh. This should create a my-awesome-test.stderr file.

  OR if you are on Windows, set the TRYBUILD=overwrite environment variable (this is done as $env:TRYBUILD="overwrite" in powershell) and run the command again.

• Inspect my-awesome-test.stderr to make sure it looks ok

• Rerun cargo test -p wasm-bindgen-macro --test ui and your tests should pass!