"Implement #isNil for Point to test isNil overwrite" ! Point methodsFor: #testing ! isNil " Responds true if the receiver is partially undefined. " ^x isNil or: [ y isNil ]! ! TestCase subclass: #TestNilOverride instanceVariableNames: '' category: 'sunit-s8'! ! TestNilOverride methodsFor: 'test'! test self assert: (Point new isNil)! !