Require valid expect

Reviewed By: cpojer

Differential Revision: D6671552

fbshipit-source-id: e254d3a308fac0802084b8d328bd3ee38c7bc8ce

.eslintrc

@@ -252,5 +252,7 @@
   // The following rules are made available via `eslint-plugin-jest`.
     "jest/no-disabled-tests": 1,
     "jest/no-focused-tests": 1,
+    "jest/no-identical-title": 1,
+    "jest/valid-expect": 1,
   }
 }