Summary of Running Tests in Rust

Main Point

This chapter discusses how to write and run tests in Rust, emphasizing the importance of testing for ensuring code correctness and reliability.

Key Concepts

Why Testing is Important

• Confidence in Code: Testing helps developers ensure their code behaves as expected.
• Error Detection: Tests can catch bugs early in the development process.

Types of Tests

• Unit Tests: Test individual functions or modules in isolation.
• Integration Tests: Test how different parts of the code work together.

Writing Tests

• Test Functions: Defined within a module using the #[cfg(test)] attribute.
• Assertions: Use assert!, assert_eq!, and assert_ne! to verify conditions.

Example of a Test Function

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

    #[test]
    fn test_add() {
        assert_eq!(add(2, 3), 5);
    }
}

In this example, test_add checks if the add function correctly adds two numbers.

Running Tests

• Use the command cargo test to run all tests in a project.
• Rust automatically discovers tests marked with the #[test] attribute.

Test Output

• When tests are run, Rust provides a summary of passed and failed tests.
• Example output:

running 1 test
test tests::test_add ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

Conclusion

Testing in Rust is straightforward and crucial for maintaining code quality. By writing unit and integration tests, developers can ensure their code is reliable and free from bugs. Use cargo test to easily run your tests and get feedback on your code’s correctness.