Configure eslint for the new eslint packages

Author: julienw

tests/.eslintrc.yml

@@ -1,6 +1,17 @@
 ---
-    env:
-        jest: true
-    rules:
-        prefer-arrow-callback: 0
-        no-mixed-requires: 0
+plugins:
+  - jest
+  - jest-dom
+  - testing-library
+extends:
+  - plugin:jest/recommended
+  - plugin:jest-dom/recommended
+  - plugin:testing-library/react
+env:
+  jest: true
+rules:
+  prefer-arrow-callback: 0
+  no-mixed-requires: 0
+  # This disallows using direct Node properties (eg: firstChild), but we have
+  # legitimate uses:
+  testing-library/no-node-access: 0