Macro save 

macro_rules! save {
    ($name: expr, $value:expr) => { ... };
}

Save the value as test results

Example:

let png_data: &[u8] = some_rendering_logic().encode_to_png();
test_results::save!("output.png", png_data);

The file will be saved in the test_results folder in the same directory as the source files.

├─ test.rs
└─ test_results
    └─ output.txt