Integration testing examples and documentation

[WillSquire]

I've been reading through the examples and docs but I can't find material on integration testing? Found a bit of information here regarding Connection::test_transaction. Is there material on this?

This is my code that contains the database connection pool:

use crate::error::Error;
use diesel::{pg::PgConnection, r2d2::ConnectionManager};
use r2d2::{Pool, PooledConnection};

pub type Connection = PooledConnection<ConnectionManager<PgConnection>>;
type ConnectionPool = Pool<ConnectionManager<PgConnection>>;

pub struct Db {
  connection_pool: ConnectionPool,
}

impl Db {
  pub fn new(
    db_user: &str,
    db_password: &str,
    db_name: &str,
    db_server: &str,
  ) -> Result<Db, Error> {
    Ok(Db {
      connection_pool: Pool::builder().max_size(15).build(
        ConnectionManager::<PgConnection>::new(format!(
          "postgres://{}:{}@{}/{}",
          db_user, db_password, db_server, db_name
        )),
      )?,
    })
  }

  pub fn connect(&self) -> Result<Connection, Error> {
    Ok(self.connection_pool.clone().get()?)
  }
}

For brevity the actual usage can be found here, which I might get away with passing a test connection if it exists.

Noticed the r2d2 feature uses TestConnection from test_helpers::*. Is the the recommended way?

[weiznich]

The following code will call begin_test_transaction for each connection in a given pool:

struct TestTransaction;

impl CustomizeConnection<DbConnection, ::diesel::r2d2::Error> for TestTransaction {
    fn on_acquire(
        &self,
        conn: &mut DbConnection,
    ) -> ::std::result::Result<(), ::diesel::r2d2::Error> {
        conn.begin_test_transaction().unwrap();
        Ok(())
    }
}

let manager = ConnectionManager::<DbConnection>::new(db_url);
    let pool = Pool::builder()
        .connection_customizer(Box::new(TestTransaction))
        .build(manager)
        .expect("Failed to init pool")

[WillSquire]

Thanks @weiznich, I've tried implementing what you've put above but I'm getting no method named 'begin_test_transaction' found for type '&mut diesel::PgConnection' in the current scope. Is this implemented for postgres or am I using the wrong connection type?

[weiznich]

Just to add the solution also to this issue:
You need to import the Connection trait into the current scope, otherwise begin_test_transaction is not found.

[Mastermindaxe]

I think a guide on testing would be very helpful.
Is there any work done on this since posting this issue? I guess this is also related to issue #1549 as it seems there is documentation on testing overall missing. Thanks in advance

[WillSquire]

@Mastermindaxe I'm not sure about documentation, but I did implement it and have an example of the path I took here: https://github.com/WillSquire/Graphy/blob/master/api/src/db/mod.rs . Not worked on it for perhaps a year though.

[weiznich]

Closed as this seems to be a duplicate of #777