tests/cases/compiler/optionalPropertiesInClasses.ts(10,7): error TS2420: Class 'C2' incorrectly implements interface 'ifoo'.
  Property 'y' is missing in type 'C2'.


==== tests/cases/compiler/optionalPropertiesInClasses.ts (1 errors) ====
    interface ifoo {
    	x?:number;
    	y:number;
    }
    
    class C1 implements ifoo {
    	public y:number;
    }
    
    class C2 implements ifoo { // ERROR - still need 'y'
          ~~
!!! error TS2420: Class 'C2' incorrectly implements interface 'ifoo'.
!!! error TS2420:   Property 'y' is missing in type 'C2'.
    	public x:number;
    }
    
    class C3 implements ifoo {
    	public x:number;
    	public y:number;
    }