Add linting rule for cypress tests to reject .only calls

client/.eslintrc.js

@@ -103,5 +103,12 @@ module.exports = {
         caughtErrorsIgnorePattern: '^_',
       },
     ],
+    'no-restricted-syntax': [
+      'error',
+      {
+        selector: "CallExpression[callee.object.name=/^(describe|it|test)$/][callee.property.name='only']",
+        message: 'Found .only in test. Please remove it before committing.',
+      },
+    ],
   },
 };