feature: remove expired items for postgres adapter #20 (#21)

Co-authored-by: nwittstruck <nwittstruck@users.noreply.github.com>

test/helpers/postgres_helper.ts

@@ -0,0 +1,40 @@
+import { Logger } from '@nestjs/common';
+import { Client } from 'pg';
+const logger = new Logger();
+
+// This is a very simple helper to make sure that the tests do not overwrite the local development database.
+export const createTestDatabaseSetup = async () => {
+  const uri: string = process.env[`STORAGE_URI`];
+
+  // This is all very specific to the docker-compose.yml. We should refactor this later. This will break when query parameters are added:
+  const parts = uri.split('/');
+  if (parts.length < 1) {
+    logger.error('No database match found');
+    return;
+  }
+  const databaseSuffix = '-test';
+  const database = parts[parts.length - 1] + databaseSuffix;
+  process.env['STORAGE_URI'] = process.env['STORAGE_URI'] + databaseSuffix;
+
+  // Set up client with uri:
+  const client = new Client({ connectionString: uri });
+  client.connect();
+
+  return client
+    .query(`CREATE DATABASE "${database}"`)
+    .catch((e) => logger.debug('Error executing query:', e)) // this will happen after the first run, so we'll discard it
+    .then(() => client.end());
+};
+
+// This helper is required for testing the postgres ttl service. It is designed specificially to clean up after each postgres spec.
+// Therefore, we don't want to include it in other specs.
+export const clearDatabase = async () => {
+  const uri: string = process.env[`STORAGE_URI`];
+  // Set up client with uri:
+  const client = new Client({ connectionString: uri });
+  client.connect();
+  return client
+    .query('DELETE FROM keyv;')
+    .catch((e) => console.error(e.stack))
+    .then(() => client.end());
+};