How to conditionally apply migrations?

[raif-s-naffah]

hi there,

i recently added a new feature to my (Rocket) web app which uses sqlx 0.8.3.

the web app now can run in 2 different modes. which one is used, incl. when running tests, is selected on the command line through an environment variable. so to run the tests in mode B i do:

MODE=b cargo t

i also have a migrations folder at the top of the project's tree where 3 migration .sql files already exist.

to test one of the modes, i need to run a migration that inserts few rows in a table. i added that migration in a new sub-directory under migrations and now i have the following tree structure:

migrations
    +-- test 
    |     +-- M4.sql
    +-- M1.sql
    +-- M2.sql
    +-- M3.sql

i also have a mock DB that i inject when running the tests. during the initialization of the server, the mock DB constructor has code like this...

conn = PgConnection::connect(&db_url).await?;
let m = Migrator::new(Path::new("./migrations")).await?;
m.run(&mut conn).await?;

i thought if i added an if w/ a similar block to the above using ./migrations/test as the source i would have a way of conditionally migrating the mock DB based on the mode but i'm getting an error like this:

thread '<unnamed>' panicked at src/db/mockdb.rs:79:26:
Failed applying test migrations to mock DB: VersionMissing(20240503004907)
thread 'db::statement::tests::test_insert_complex' panicked at src/db/mockdb.rs:84:10:
Failed setting up mock DB: Any { .. }

the number referenced in VersionMissing is in fact the integer part of M1 migration sql file, which looks like a timestamp —btw. all migrations were "added" using the default sqlx migrate add xxx form.

would appreciate it if you can tell me if it's possible to selectively and conditionally apply a set of migrations from different folders w/o duplicating common .sql migration files? if yes, how?

thanks in anticipation + cheers;
rsn