Add some tests for assertf

Author: sogaiu

test/suite-boot.janet

@@ -986,4 +986,14 @@
 (assert (deep= (get (dyn 'a) :source-form) source))
 (setdyn *debug* nil)
 
+# issue #1516
+(assert (assertf true) "assertf 1 argument")
+(assert (assertf true "fun message") "assertf 2 arguments")
+(assert (assertf true "%s message" "mystery") "assertf 3 arguments")
+(assert (assertf (not nil) "%s message" "ordinary") "assertf not nil")
+(assert-error "assertf error 1" (assertf false))
+(assert-error "assertf error 2" (assertf false "fun message"))
+(assert-error "assertf error 3" (assertf false "%s message" "mystery"))
+(assert-error "assertf error 4" (assertf nil "%s %s" "alice" "bob"))
+
 (end-suite)