classTest{publicneedsToBeDefined?:number;privatenotReadonlyFoo?:number;privatenotReadonlyBar?:number;publictestMethodFoo(){if(!this.classPropertyGuard()){return;}this.notReadonlyFoo=1;}publictestMethodBar(){if(!this.normalTypeGuard(this.needsToBeDefined)){return;}this.notReadonlyBar=2;}privateclassPropertyGuard():this is this&{needsToBeDefined:number}{returnthis.needsToBeDefined!==undefined;}privatenormalTypeGuard(value:number|undefined):value isnumber{returnvalue!==undefined;}}

module.exports={parser:"@typescript-eslint/parser",rules:{"@typescript-eslint/prefer-readonly":"error"},};

Member 'notReadonlyFoo' is never reassigned; mark it as `readonly`. 4:3 - 4:35