add minimal ?@, ?? tests to racket-test-core

pkgs/racket-test-core/tests/racket/stx.rktl

@@ -2622,6 +2622,30 @@
           [(_ () (_app cons one . _))
            (equal? (syntax-line #'cons) (syntax-line #'one))])))
 
+;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Minimal tests for syntax and ?@, ??
+;; More tests in pkgs/racket-test/tests/stxparse/test-syntax.rkt
+
+(test '(a 1 b 2 c 3)
+      'syntax
+      (with-syntax ([(x ...) #'(a b c)] [(y ...) #'(1 2 3)])
+        (syntax->datum #'((?@ x y) ...))))
+
+(test '(1 2 3 4)
+      'syntax
+      (with-syntax ([xs #'(2 3)])
+        (syntax->datum #'(1 (?@ . xs) 4))))
+
+(test '(1 2 3)
+      'syntax
+      (with-syntax ([x #'(1 2 3)])
+        (syntax->datum #'(?? x "missing"))))
+
+(test '(4 5 6)
+      'syntax
+      (with-syntax ([(x ...) #'(4 5 6)])
+        (syntax->datum #'((?? x) ...))))
+
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (report-errs)