Make production tests always run against dist/ (attempt 2) (#2942)

* Make production tests always run against dist/

* Try to mock process.stdin instead of get-stream

* fix: mock `get-stream` from `index.js`

* refactor: remove unnecessary variable

* Try `transform: {}` in jest.config.js

* Add comment explaining the unusual get-stream mocking

jest.config.js

@@ -13,5 +13,6 @@ module.exports = {
     "<rootDir>/src/doc-debug.js",
     "<rootDir>/src/clean-ast.js",
     "<rootDir>/src/deprecated.js"
-  ]
+  ],
+  transform: {}
 };