Add more forall test cases.

builtin/core.wren

@@ -17,7 +17,7 @@ class Sequence {
 
   forall(f) {
     for (element in this) {
-      if (f.call(element) != true) return false
+      if (!f.call(element)) return false
     }
     return true
   }

src/wren_core.c

@@ -60,7 +60,7 @@ static const char* libSource =
 "\n"
 "  forall(f) {\n"
 "    for (element in this) {\n"
-"      if (f.call(element) != true) return false\n"
+"      if (!f.call(element)) return false\n"
 "    }\n"
 "    return true\n"
 "  }\n"

test/list/forall.wren

@@ -2,8 +2,8 @@ var a = [1, 2, 3]
 var b = a.forall {|x| x > 1 }
 IO.print(b) // expect: false
 
-var c = a.forall {|x| x.toString }
-IO.print(c) // expect: false
-
 var d = a.forall {|x| x > 0 }
 IO.print(d) // expect: true
+
+var e = [].forall {|x| false }
+IO.print(e) // expect: true

test/list/forall_non_bool_returning_fn.wren

@@ -0,0 +1 @@
+[1, 2, 3].forall {|x| "string" } // expect runtime error: String does not implement method '!' with 0 arguments.

test/list/forall_non_function_arg.wren

@@ -0,0 +1 @@
+[1, 2, 3].forall("string") // expect runtime error: String does not implement method 'call' with 1 argument.