Made automations test database more reliable (TryGhost#28520)

ref https://github.com/TryGhost/Ghost/actions/runs/27375153163/

This database will soon be removed, but let's make it a little more
reliable in the meantime because CI is flaky. Let's ensure there's just
one connection at a time.

Author: EvanHahn

ghost/core/core/server/services/automations/automations-api.ts

@@ -71,13 +71,13 @@ const editAutomationDataSchema = z.object({
     edges: z.array(edgeSchema)
 }).strict();
 
-let testDatabase: Knex | null = null;
+let testDatabasePromise: Promise<Knex> | null = null;
 
 const repository = createFakeDatabaseAutomationsRepository({
     getDatabase: async () => {
         if (process.env.NODE_ENV?.startsWith('testing')) {
-            testDatabase ??= await temporaryFakeAutomationsDatabase.createTemporaryFakeAutomationsDatabase();
-            return testDatabase;
+            testDatabasePromise ??= temporaryFakeAutomationsDatabase.createTemporaryFakeAutomationsDatabase();
+            return await testDatabasePromise;
         }
         return await temporaryFakeAutomationsDatabase.getTemporaryFakeAutomationsDatabase();
     }
@@ -320,6 +320,6 @@ export async function retryStep(...args: Parameters<AutomationsRepository['retry
 
 export function _resetTestDatabase() {
     if (process.env.NODE_ENV?.startsWith('testing')) {
-        testDatabase = null;
+        testDatabasePromise = null;
     }
 }

ghost/core/core/server/services/automations/temporary-fake-database.ts

@@ -20,6 +20,10 @@ export async function createTemporaryFakeAutomationsDatabase(): Promise<Knex> {
         connection: {
             filename: ':memory:'
         },
+        pool: {
+            min: 1,
+            max: 1
+        },
         useNullAsDefault: true
     });