... that depending on the code samples you write in tests, the RuleTester parser property must be set accordingly (this can be done on a test-by-test basis). The default JavaScript parser must be replaced because Vue.js single file components are not plain JavaScript, but a custom file format. vue-eslint-parser is a replacement parser that generates an enhanced AST with nodes that represent specific parts of the template syntax, as well as the contents of the script tag.