Update.

test/await/await_fn_class_instance.wren

@@ -0,0 +1,50 @@
+// retoor <retoor@molodetz.nl>
+
+import "scheduler" for Scheduler, Future
+
+class Counter {
+    construct new(start) {
+        _value = start
+    }
+
+    value { _value }
+
+    add(n) {
+        var op = async { |x|
+            _value = _value + x
+            return _value
+        }
+        return await op(n)
+    }
+
+    subtract(n) {
+        var op = async { |x|
+            _value = _value - x
+            return _value
+        }
+        return await op(n)
+    }
+
+    reset() {
+        var op = async {
+            _value = 0
+            return _value
+        }
+        return await op()
+    }
+}
+
+var counter = Counter.new(10)
+System.print(counter.value) // expect: 10
+
+System.print(counter.add(5)) // expect: 15
+System.print(counter.value) // expect: 15
+
+System.print(counter.subtract(3)) // expect: 12
+System.print(counter.value) // expect: 12
+
+System.print(counter.reset()) // expect: 0
+System.print(counter.value) // expect: 0
+
+System.print(counter.add(10)) // expect: 10
+System.print(counter.subtract(3)) // expect: 7