class foo {} class bar extends foo {} class baz {} // Set class SetTest { Null foo() { Int n = 1; bar b = new bar(); s = 2; // 1/3 failure of clause 1 (nonexistent variable) n = new foo(); // 2/3 failure of clauses 2 and 3 (subtype mismatch) b = new foo(); // 3/3 failure of clauses 2 and 3 (inverted sub- and supertypes) b = new bar(); // success } } 1