Crate docfg 

Crate thet facilitates the documentation of feature-gated code. This crate requires the use of the doc_cfg nightly feature.

Remember to add the following to your Cargo.toml file for the crate make efect when documenting on docs.rs

[package.metadata.docs.rs]
all-features = true
rustdoc-args = ["--cfg", "docsrs"]

And when generating local documentation, use cargo rustdoc -- --cfg docsrs

Example

#[docfg(test)]
fn test () {
    // ...  
}

#[cfg_attr(docsrs, doc(cfg(test)))]
#[cfg(test)]
fn test () {
    // ...
}

Attribute Macros

docfg