-(test-eqv 2 (length (find col '((a . 1)))))
-(test-eqv 1 (length (find col '((a . 1) (b . 2)))))
-(test-eqv 0 (length (find col '((a . "test")))))
+(test-eqv 3 (length (find col)))
+(test-eqv 2 (length (find col ($eq 'a 1))))
+(test-eqv 1 (length (find col ($eq 'a 1) ($eq 'b 2))))
+(test-eqv 0 (length (find col ($eq 'a "test"))))
+
+(test-eqv 2 (length (find col ($exists 'b))))
+(test-eqv 2 (length (find col ($not ($exists 'c)))))