feat: add dont-cleanup-after-each.js (#435)

This is just a simple file that sets the RTL_SKIP_AUTO_CLEANUP environment variable so that RTL doesn't setup automatic cleanup. This makes it easier for folks who don't want to write their tests in an isolated way. It's totally not recommended, but it will hopefully reduce pain while people migrate from one testing style to another.

Author: Kent C. Dodds

dont-cleanup-after-each.js

@@ -0,0 +1 @@
+process.env.RTL_SKIP_AUTO_CLEANUP = true

package.json

@@ -25,6 +25,7 @@
     "dist",
     "typings",
     "cleanup-after-each.js",
+    "dont-cleanup-after-each.js",
     "pure.js"
   ],
   "keywords": [