Issue #450: Create Drush command to delete tables left over from runn…

…ing tests

drush/Commands/bc_dc/BcDcTestCleanupDrushCommands.php

@@ -0,0 +1,59 @@
+<?php
+
+namespace Drush\Commands\bc_dc;
+
+use Drush\Commands\DrushCommands;
+use Drush\Sql\SqlBase;
+
+/**
+ * Drush command file.
+ */
+class BcDcTestCleanupDrushCommands extends DrushCommands {
+
+  /**
+   * Drush command to delete tables left over from running tests.
+   *
+   * @param string $db_url
+   *   The URL of the database, for example, "pgsql://user:pass@localhost/db".
+   *
+   * @command bcdc:clean-test-tables
+   *
+   * @usage bcdc:clean-test-tables pgsql://user:pass@localhost/db
+   *
+   * @todo It ought to be possible for Drush to get the DB URL from the site
+   * config instead of requiring it as param.
+   */
+  public function deleteTestTables(string $db_url): void {
+    $msg = dt('Deleting tables left over from running tests...');
+    $this->output()->writeln($msg);
+
+    $database = SqlBase::create(['db-url' => $db_url]);
+
+    $query = 'DO
+    $do$
+    BEGIN
+      EXECUTE (
+        SELECT \'DROP TABLE \' || string_agg(format(\'%I.%I\', schemaname, tablename), \', \')
+        FROM (
+          SELECT *
+          FROM pg_catalog.pg_tables t
+          WHERE schemaname NOT LIKE \'pg\_%\' -- Exclude system schemas.
+            AND tablename LIKE \'test%\' -- Prefix of tables to remove.
+          LIMIT 500 -- Limit to avoid running out of memory.
+        ) sub
+      );
+    END
+    $do$;';
+
+    $success = $database->query($query);
+
+    if ($success) {
+      $msg = dt('Done.');
+      $this->output()->writeln($msg);
+    }
+    else {
+      throw new \Exception(dt('Query failed.'));
+    }
+  }
+
+}