Crate runtime_macros

This crate offers a way to emulate the process of procedural macro expansion at run time. It is intended for use with code coverage tools like tarpaulin, which can’t measure the code coverage of anything that happens at compile time.

Currently, runtime-macros only works with functionlike! procedural macros. Custom derive may be supported in the future if there’s demand.

To use it, add a test case to your procedural macro crate that calls emulate_macro_expansion on a .rs file that calls the macro. Most likely, all the files you’ll want to use it on will be in your /tests directory. Once you’ve completed this step, any code coverage tool that works with your crate’s test cases will be able to report on how thoroughly you’ve tested the macro.

See the /examples directory in the repository for working examples.

Enums

Error

The error type for emulate_macro_expansion_fallible. If anything goes wrong during the file loading or macro expansion, this type describes it.

Functions

emulate_macro_expansionDeprecated

This type is like emulate_macro_expansion_fallible but automatically unwraps any errors it encounters. As such, it’s deprecated due to being less flexible.

emulate_macro_expansion_fallible

Parses the given Rust source code file, searching for macro expansions that use macro_path. Each time it finds one, it calls proc_macro_fn, passing it the inner TokenStream just as if the macro were being expanded. The only effect is to verify that the macro doesn’t panic, as the expansion is not actually applied to the AST or the source code.