my-rust-studies

A simple repository where I put my own tests while learning Rust reading the Rust Book.

Cargo

cargo new PROJECT_NAME Create a new project.

cargo build => Build the current project, after this the executable file will be available on /target folder.

cargo run => Compile the current project and run it, on the same command.

cargo check => Check the code to make sure it compiles, but not run it.

Diferences between Statements and Expressions.

Statements => Are instructions that perform some actions and do not return a value. Expressions => Evaluate to a resultant value.

Tests

pub fn add_two(value: i32) -> i32 {
    if(value < 0){
        panic!("Number need be positive");
    }
    value + 2
}

#[cfg(test)]
mod test {
    use super::*

    #[test]
    fn my_test_function(){
        let result = add_two(4);
        assert_eq!(result, 4);
        assert_ne!(result, 5);
    }

    #[test]
    #[should_panic(expected="need be positive")]
    fn my_panic_test(){
        add_two(-1);
    }

    #[test]
    #[ignore]
    fn this_test_will_be_ignored(){
        add_two(-2);
    }
}

#[cfg(test)] -> Tells to compiler to run tests code only on run cargo test, not on cargo build.

Integration tests

All integration tests go on Tests directory, on the top of the project.

adder
├── Cargo.lock
├── Cargo.toml
├── src
│   └── lib.rs
└── tests
    └── integration_test.rs

To create a code to be used on more than on test, an not run it as test itself, we use the pattern with mod.rs.

├── Cargo.lock
├── Cargo.toml
├── src
│   └── lib.rs
└── tests
    ├── common
    │   └── mod.rs
    └── integration_test.rs

Tests useful flags

For all moments

All are initiated by $ cargo test -- --test-threads=1 -> By default, tests are runned on parallel, this force to Rust compiler use only 1 thread.

-- --show-output -> By default, println! macros only inside the functions being testeds, only appear on tests who fail, this force to appear on ALL tests.

{HERE_IS_THE_TEST_NAME} -> This code run only the test passed as argument.

{HERE_IS_PART_OF_THE_TEST_NAME} -> Run all tests who match with this substring in his name.

--test -> Run only integration tests, we can specify a test name, or a file name to run all tests on it.

When using the derive #[ignore]

-- --ignored -> Run only ignored tests.

-- --inclued-ignored -> Run all tests, including ignored tests.

Common questions. Why print! execute after asking for an input when declared before?