Glow Plug

A simple testing macro #[glow_plug::test] for diesel.

Glow Plug is a Rust testing library designed to simplify database testing with Diesel. It provides a macro that automatically sets up a new, clean database and applies migrations for each test, ensuring test isolation and reliability. With Glow Plug, you can confidently write tests that interact with a real database without worrying about tests interfering with each other or having hidden dependencies.

Example

The connection provided to the test is always a clean, empty database.

Example 1.

#[glow_plug::test]
fn test_the_database_is_empty(mut conn: PgConnection) {
    let results = posts
        .filter(published.eq(true))
        .select(Post::as_select())
        .load(conn)
        .expect("Error loading posts");

    assert_eq!(results.len(), 0);
}

Example 2.

Also can handle test that return results.

#[glow_plug::test]
fn test_insert_user(mut conn: PgConnection) -> Result<()> {
    let user = NewUser {
        id: "12345",
        ...
    };

    diesel::insert_into(users)
        .values(user)
        .execute(&mut conn)?;

    let user = users
        .filter(user_account::id.eq("12345"))
        .first::<User>(&mut conn)?;

    assert_eq!(user.id, "12345");
}

Async Example

Enabling the tokio feature will allow you to run async tests.

#[glow_plug::test]
async fn test_insert_user(mut conn: PgConnection) -> Result<()> {
    let result = something_async().await?;
    assert(result);
}

Installation

1. Add glow_plug as a dev dependency.

[dev-dependencies]
glow_plug = { version = "the-version", features = ["tokio"] }

2. Setup migrations

The macro by default just assumes the migrations are available by crate::MIGRATIONS. So in the root of your project you must declare the MIGRATIONS.

These are just reexported from diesel_migrations so if you already have the embeded migrations setup you can continue to just use those and remove the #[cfg(test)]

// main.rs or lib.rs

#[cfg(test)]
const MIGRATIONS: glow_plug::EmbeddedMigrations = glow_plug::embed_migrations!();

3. Make sure the DATABASE_URL in the .env file is set.

DATABASE_URL=postgres://...

4. Run the tests!

cargo test

Contributing

PR's are welcome! If people find this useful would love some ideas on how to make this more configurable for other setups since the current setup requires some additional things and the macro just assumes where the MIGRATIONS are and that you use .env.

Credits

This is heavily inspired by sqlx's #[sqlx::test] macro and attempts to bring its usefulness to diesel. So credit to them for the idea!

License

Copyright © 2024 Wes Wickwire. All rights reserved. Distributed under the MIT License.

See the LICENSE file.