Cannot clear database inside a transaction

[varanauskas]

Issue Description

queryRunner.clearDatabase() fails if trying to run inside a transaction.

Expected Behavior

It clears the database inside the transaction, then operations can be performed inside the transaction on a temporarily empty database, and that transaction can later be reverted

Actual Behavior

It throws TransactionAlreadyStartedError when trying to clearDatabase inside a transaction

// TransactionAlreadyStartedError: Transaction already started for the given connection, commit current transaction before starting a new one.

Steps to Reproduce

1. Connect to a databsae
2. Start Transaction
3. clearDatabase
4. It throws TransactionAlreadyStartedError

const connection = await createConnection();
const queryRunner = connection.createQueryRunner();
await queryRunner.startTransaction();
await queryRunner.clearDatabase();
// ^ This fails with `TransactionAlreadyStartedError`

My Environment

Dependency	Version
Operating System	macOS
Node.js version	16.13.1
Typescript version	4.5.4
TypeORM version	0.2.41

Additional Context

I want to clearDatabase inside a transaction, so I could get a temporary blank slate database, and then run migrations inside the same transaction, so I can determine what tables are missing after running all migrations regardless of, and without modifying the initial state of the database

Relevant Database Driver(s)

DB Type	Reproducible
aurora-data-api	no
aurora-data-api-pg	no
better-sqlite3	no
cockroachdb	no
cordova	no
expo	no
mongodb	no
mysql	no
nativescript	no
oracle	no
postgres	yes
react-native	no
sap	no
sqlite	no
sqlite-abstract	no
sqljs	no
sqlserver	no

Are you willing to resolve this issue by submitting a Pull Request?

• ✅ Yes, I have the time, and I know how to start.
• ✖️ Yes, I have the time, but I don't know how to start. I would need guidance.
• ✖️ No, I don’t have the time, but I can support (using donations) development.
• ✖️ No, I don’t have the time and I’m okay to wait for the community / maintainers to resolve this issue.

[varanauskas]

I suggest either:

• Checking if a transaction is in progress inside clearDatabase, if so, reverting a transaction that is being cleared
• Adding an options = { startTransaction: true } argument to clearDatabase where a user could override the transaction starting