compiletest_rs 0.0.11

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This project is an attempt at extracting the compiletest utility from the Rust compiler.

The compiletest utility is useful for library and plugin developers, who want to include test programs that should fail to compile, issue warnings or otherwise produce compile-time output.

To use in your project

To use compiletest-rs in your application, add the following to Cargo.toml

compiletest_rs = "*"

Create a tests folder in the root folder of your project. Create a test file with something like the following:

extern crate compiletest_rs as compiletest;

use std::path::PathBuf;

fn run_mode(mode: &'static str) {
    let mut config = compiletest::default_config();
    let cfg_mode = mode.parse().ok().expect("Invalid mode");

    config.mode = cfg_mode;
    config.src_base = PathBuf::from(format!("tests/{}", mode));


fn compile_test() {

Each mode corresponds to a folder with the same name in the tests folder. That is for the compile-fail mode the test runner looks for the tests/compile-fail folder.

Adding flags to the Rust compiler is a matter of assigning the correct field in the config.

config.target_rustcflags = Some("-L target/debug".to_string());

This is useful (and necessary) for library development. Note that other secondary library dependencies may have their build artifacts placed in different (non-obvious) locations and these locations must also be added.


See the test-project folder for a complete working example using the compiletest-rs utility. Simply cd test-project and cargo test to see the tests run.


  • The run-pass mode is strictly not necessary since it's baked right into Cargo, but I haven't bothered to take it out
  • Find out if it is possible to capture the build flags during compilation. Then it should be possible to for compiletest-rs to capture (among other things) build dependencies (like -L). In the case a library would depend on a second library, the generated .rlib for the second library may end up in non-obvious places (and missing from the build path). Currently the work-around is to explicitly list the search paths as extra rustc flags.