List.addAll().

test/list/add.wren

@@ -1,6 +1,4 @@
-var a = []
-a.add(1)
-IO.print(a) // expect: [1]
+var a = [1]
 a.add(2)
 IO.print(a) // expect: [1, 2]
 a.add(3)

test/list/add_all.wren

@@ -0,0 +1,11 @@
+var a = [1]
+a.addAll([2, 3])
+IO.print(a) // expect: [1, 2, 3]
+a.addAll([])
+IO.print(a) // expect: [1, 2, 3]
+a.addAll(4..6)
+IO.print(a) // expect: [1, 2, 3, 4, 5, 6]
+
+// Returns argument.
+var range = 7..9
+IO.print(a.addAll(range) == range) // expect: true