kpostgres_fixture

This provides two main functions: - with_temporary_postgres: Creates a temporary postgres instance using docker. - with_temporary_database: Creates a temporary DATABASE inside an existing postgres instance.

They both pass the parameters and TlsMode so that you can create a connection however you want.

This is useful for things like running migrations in a test database in an isolated environment.

The best example of usage is taken directly from my tests:

```rust

[cfg(test)]

mod tests { use super::*;

use std::sync::{Once, ONCE_INIT};

static INIT: Once = ONCE_INIT;

#[cfg(feature = "docker")]
#[test]
fn temp_pg() {
    INIT.call_once(|| {
        env_logger::init();
    });

    let result = with_temporary_postgres("postgres:11", |params, tls_mode, _| -> Result<()> {
        with_temporary_database(params, tls_mode, |params, tls_mode| -> Result<()> {
            let conn = Connection::connect(params, tls_mode)?;
            conn.batch_execute("CREATE TABLE test()")?;
            conn.execute("TABLE test", &[])?;
            Ok(())
        })?
    })
    .expect("Failed to create temporary database");
    println!("{:#?}", result);
    result.expect("Inner result failed");
}

#[test]
fn temp_db() {
    INIT.call_once(|| {
        env_logger::init();
    });

    let connect_params = ConnectParams::builder()
        .port(5432)
        .user("postgres", None)
        .database("postgres")
        .build(params::Host::Tcp("localhost".to_owned()));
    let result = with_temporary_database(
        connect_params,
        TlsMode::None,
        |params, tls_mode| -> Result<()> {
            let conn = Connection::connect(params, tls_mode)?;
            conn.batch_execute("CREATE TABLE test()")?;
            conn.execute("TABLE test", &[])?;
            Ok(())
        },
    )
    .expect("Failed to create temporary database");
    println!("{:#?}", result);
    result.expect("Inner result failed");
}

} ```