[test] Add syntax and scoping tests for type rec (#1944)

Author: rossberg

test/core/type-rec.wast

@@ -1,3 +1,39 @@
+;; Syntax and Scoping
+
+(module
+  (type (func (param (ref 0)) (result (ref 0))))
+  (rec
+    (type (func (param (ref 2))))
+    (type (func (result (ref 1))))
+  )
+
+  (rec)
+  (rec (type (func)))
+  (rec (type $t (func)))
+  (rec (type $t1 (func)) (type (func)) (type $t2 (func)))
+  (rec (type $g (func (param (ref $g)) (result (ref $g)))))
+  (rec
+    (type $h (func (param (ref $k))))
+    (type $k (func (result (ref $h))))
+  )
+)
+
+(assert_invalid
+  (module
+    (type (func (param (ref 1))))
+    (type (func))
+  )
+  "unknown type"
+)
+(assert_invalid
+  (module
+    (rec (type (func (param (ref 1)))))
+    (rec (type (func)))
+  )
+  "unknown type"
+)
+
+
 ;; Static matching of recursive types
 
 (module