How to mock with rocket

[open-schnick]

Hi :)
I feel like i am missing something here.
I have an rocket app that uses a sea-orm database pool.
The application looks like the example with pool looking like this:

#[derive(Database, Debug)]
#[database("database")]
pub struct Db(SeaOrmPool);

#[derive(Debug)]
pub struct SeaOrmPool {
    pub conn: sea_orm::DatabaseConnection,
}

#[async_trait]
impl sea_orm_rocket::Pool for SeaOrmPool {
    type Connection = sea_orm::DatabaseConnection;
    type Error = sea_orm::DbErr;

    async fn init(figment: &Figment) -> Result<Self, Self::Error> {
        let options = parse_rocket_config(figment);
        let conn = sea_orm::Database::connect(options).await?;

        Ok(SeaOrmPool { conn })
    }

    fn borrow(&self) -> &Self::Connection {
        &self.conn
    }
}

Looking at the src i see that connect automatically gives me a mocked connection if the mock feature is enabled.
But it only works when a working database feature is enabled like sqlx-postgres and the respective uri is valid.
But then it always uses the real database connection instead of the mocked one because the mocked one is the last if to be checked.
The connect function:

// if the uri is a valid postgres uri it goes here
#[cfg(feature = "sqlx-postgres")]
if DbBackend::Postgres.is_prefix_of(&opt.url) {
    return crate::SqlxPostgresConnector::connect(opt).await;
}
// if it isn't it goes here but the mock connector only accepts valid postgres uris because the feature is enabled. see below
#[cfg(feature = "mock")]
if crate::MockDatabaseConnector::accepts(&opt.url) {
    return crate::MockDatabaseConnector::connect(&opt.url).await;
}
Err(DbErr::Conn(format!(
    "The connection string '{}' has no supporting driver.",
    opt.url
)))

The implementation of the MockDatabaseConnector looks like this:

pub fn accepts(string: &str) -> bool {
    #[cfg(feature = "sqlx-postgres")]
    if DbBackend::Postgres.is_prefix_of(string) {
        return true;
    }
    false
}

It only returns the needed true if the postgres feature is enabled AND its a valid uri but then this code will never be reached because its a valid uri for the valid database.

Is this even the intentional way to do it?
I feel like i am missing something here....

[open-schnick]

So it looks like i indeed missed something.
I thought you could just change a feature flag and sea-orm automatically uses a mocked implementation.
This is not the case.
You have to provide a different implementation of the sea_orm_rocket::Pool trait when running tests.
I implemented that by using a feature flag, that also enables the mock feature in sea orm.
Cargo.toml:

[features]
mock = ["sea-orm/mock"]

[dependencies]
sea-orm = { version = "0.9.0", features = ["sqlx-postgres", "runtime-tokio-native-tls"] }

Fixed code:

#[derive(Database, Debug)]
#[database("database")]
pub struct Db(SeaOrmPool);

#[derive(Debug)]
#[cfg_attr(not(feature = "mock"), derive(Clone))]
pub struct SeaOrmPool {
    pub conn: sea_orm::DatabaseConnection,
}

/// The real pool implementation using the real database
#[async_trait]
#[cfg(not(feature = "mock"))]
impl Pool for SeaOrmPool {
    type Connection = sea_orm::DatabaseConnection;
    type Error = sea_orm::DbErr;

    async fn init(figment: &Figment) -> Result<Self, Self::Error> {
        let options = parse_rocket_config(figment);
        let conn = sea_orm::Database::connect(options).await?;
        Ok(Self { conn })
    }

    fn borrow(&self) -> &Self::Connection {
        &self.conn
    }
}

/// Mocked implementation of the database pool.
#[async_trait]
#[cfg(feature = "mock")]
impl Pool for SeaOrmPool {
    type Connection = sea_orm::DatabaseConnection;
    type Error = sea_orm::DbErr;

    async fn init(_figment: &Figment) -> Result<Self, Self::Error> {
        // add mocking logic
        let conn = sea_orm::MockDatabase::new(sea_orm::DatabaseBackend::Postgres).into_connection();
        Ok(Self { conn })
    }

    fn borrow(&self) -> &Self::Connection {
        &self.conn
    }
}

[billy1624]

Hey @open-schnick, perhaps you want to checkout our Rocket example with mock testing (work-in-progress)

• Demonstrate how to mock test SeaORM by separating core implementation from the web API #890

[open-schnick]

Hi @billy1624 thanks for your answer, i already looked at the examples but it was not quite what i was looking for.
I see that its easy to mock the DAOs of the database, but - correct me if i am wrong - this does not allow me to start rocket (e.g in an integration test) without providing the real database.

[open-schnick]

...Which i was looking for.

[billy1624]

Correct! That's the way of doing it, if you want to use mock connection inside Rocket, e.g. your code snippet provided above.

[open-schnick]

Perfect thx again :)