feat(Migrator): allow passing transactions to Migrator.

src/migration/migrator.ts

@@ -526,7 +526,16 @@ export class Migrator {
       }
     }
 
-    if (adapter.supportsTransactionalDdl && !this.#props.disableTransactions) {
+    if (this.#props.db.isTransaction) {
+      if (!adapter.supportsTransactionalDdl) {
+        throw new Error('Transactional DDL is not supported in this dialect. Passing a transaction to this migrator would result in failure or unexpected behavior.')
+      }
+
+      return run(this.#props.db)
+    } else if (
+      adapter.supportsTransactionalDdl &&
+      !this.#props.disableTransactions
+    ) {
       return this.#props.db.transaction().execute(run)
     } else {
       return this.#props.db.connection().execute(run)

test/node/src/migration.test.ts

@@ -825,6 +825,43 @@
           expect(transactionSpy.called).to.be.false
         }
       })
+
+      it('should run migrations using a provided transaction', async () => {
+        const migrationName = 'trx_connection_method_fail_case'
+        const executedUpMethodsForThisTest: string[] = []
+
+        const testSpecificProvider: MigrationProvider = {
+          getMigrations: async () => ({
+            [migrationName]: {
+              async up(_db: Kysely<any>): Promise<void> {
+                executedUpMethodsForThisTest.push(migrationName)
+              },
+              async down(_db: Kysely<any>): Promise<void> {},
+            },
+          }),
+        }
+
+        const trx = await db.startTransaction().execute()
+
+        const migratorInTransaction = new Migrator({
+          db: trx,
+          provider: testSpecificProvider,
+        })
+
+        const { results, error } = await migratorInTransaction.migrateUp()
+
+        await trx.rollback().execute().catch(() => {})
+
+        expect(error).to.be.undefined
+        expect(results).to.eql([
+          { migrationName, direction: 'Up', status: 'Success' },
+        ])
+
+        expect(executedUpMethodsForThisTest).to.eql(
+          [migrationName],
+          "The migration's 'up' method should have been executed.",
+        )
+      })
     })
 
     describe('migrateDown', () => {