Update.

test/await/await_fn_class_service.wren

@@ -0,0 +1,65 @@
+// retoor <retoor@molodetz.nl>
+
+import "scheduler" for Scheduler, Future
+import "timer" for Timer
+
+class CacheService {
+    construct new() {
+        _cache = {}
+    }
+
+    get(key) {
+        var op = async { |k|
+            Timer.sleep(1)
+            return _cache.containsKey(k) ? _cache[k] : null
+        }
+        return await op(key)
+    }
+
+    set(key, value) {
+        var op = async { |k, v|
+            Timer.sleep(1)
+            _cache[k] = v
+            return true
+        }
+        return await op(key, value)
+    }
+
+    has(key) {
+        var op = async { |k|
+            return _cache.containsKey(k)
+        }
+        return await op(key)
+    }
+
+    clear() {
+        var op = async {
+            _cache = {}
+            return true
+        }
+        return await op()
+    }
+
+    getOrSet(key, defaultValue) {
+        if (this.has(key)) {
+            return this.get(key)
+        }
+        this.set(key, defaultValue)
+        return defaultValue
+    }
+}
+
+var cache = CacheService.new()
+
+System.print(cache.has("foo")) // expect: false
+System.print(cache.get("foo")) // expect: null
+
+System.print(cache.set("foo", "bar")) // expect: true
+System.print(cache.has("foo")) // expect: true
+System.print(cache.get("foo")) // expect: bar
+
+System.print(cache.clear()) // expect: true
+System.print(cache.has("foo")) // expect: false
+
+System.print(cache.getOrSet("baz", "default")) // expect: default
+System.print(cache.get("baz")) // expect: default