Silly.

Author: peterwilsoncc

tools/local-env/scripts/install.js

@@ -42,7 +42,7 @@ writeFileSync( 'wp-tests-config.php', testConfig );
 wait_on( {
 	resources: [
 		`tcp:localhost:${process.env.LOCAL_PORT}`
-		`tcp:localhost:3306`
+		`tcp:mysql:3306`
 	],
 	timeout: 3000,
 } )