feat: (experimental feature) applyAspect to join advice together in a…

… single declaration
k1r0s · Dec 13, 2017 · 074a022 · 074a022
1 parent f93ba88
commit 074a022
Show file tree

Hide file tree

Showing 5 changed files with 98 additions and 1 deletion.
diff --git a/src/apply-aspect.ts b/src/apply-aspect.ts
@@ -0,0 +1,14 @@
+export function applyAspect(advicePool: any) {
+  return function(target) {
+    for (let key in advicePool) {
+      if(key === "constructor") {
+        advicePool[key].forEach(advice => target = advice(target))
+      } else {
+        advicePool[key].forEach(advice => {
+          Object.defineProperty(target.prototype, key, advice(target, key, Object.getOwnPropertyDescriptor(target.prototype, key)))
+        })
+      }
+    }
+    return target
+  }
+}
diff --git a/src/index.ts b/src/index.ts
@@ -1,3 +1,4 @@
 export { afterMethod, beforeMethod, afterInstance, beforeInstance } from "./decorators"
 export { AdviceRef, ClassSignature, Metadata, MethodSignature } from "./interfaces"
-export { onException } from "./onException"
+export { onException } from "./on-exception"
+export { applyAspect } from "./apply-aspect"
diff --git a/src/interfaces.ts b/src/interfaces.ts
@@ -24,3 +24,12 @@ export interface MethodSignature<B, K> {
 export interface ClassSignature<B> {
   (target: B)
 }
+
+export interface AspectBuilder {
+  (definition: AspectDefinition)
+}
+
+export interface AspectDefinition {
+  decorateClass: Function,
+  decorateMethod: Function,
+}
diff --git a/src/onException.ts → src/on-exception.ts b/src/onException.ts → src/on-exception.ts
diff --git a/test/aspect.spec.ts b/test/aspect.spec.ts
@@ -0,0 +1,73 @@
+import { applyAspect, beforeMethod, afterMethod } from "../src"
+
+const methodSpy = jest.fn()
+
+const Delay = secs => meta => setTimeout(meta.commit, secs)
+
+const Cache = (_ => {
+  const CACHE_KEY = "#CACHE"
+  return {
+    read: meta => {
+      if (!meta.scope[CACHE_KEY]) meta.scope[CACHE_KEY] = {}
+
+      if (meta.scope[CACHE_KEY][meta.key]) {
+        meta.result = meta.scope[CACHE_KEY][meta.key]
+        meta.prevent()
+      }
+    },
+    write: meta => {
+      meta.scope[CACHE_KEY][meta.key] = meta.result
+    }
+  }
+})()
+
+@applyAspect({
+  "_veryHeavyCalculation": [beforeMethod(Cache.read), afterMethod(Cache.write)],
+  "doSomething": [beforeMethod(Delay(300))]
+})
+class Person {
+  name
+  age
+  constructor (name, yearBorn) {
+    this.name = name
+    this.age = new Date(yearBorn, 1, 1)
+  }
+
+  _veryHeavyCalculation () {
+    methodSpy()
+    const today = new Date()
+    return today.getFullYear() - this.age.getFullYear()
+  }
+
+  sayHello () {
+    return `hello, I'm ${this.name}, and I'm ${this._veryHeavyCalculation()} years old`
+  }
+
+  doSomething (cbk) {
+    cbk()
+  }
+}
+
+let personInstance
+
+describe("advance reflect.advice specs", () => {
+  beforeAll(() => {
+    personInstance = new Person("Manuelo", 1998)
+  })
+
+  it("cache advices should avoid '_veryHeavyCalculation' to be called more than once", () => {
+    personInstance.sayHello()
+    personInstance.sayHello()
+    personInstance.sayHello()
+    expect(methodSpy).toHaveBeenCalledTimes(1)
+
+  })
+
+  it("Delay advice should stop the execution for at least one segond", done => {
+    const time = Date.now()
+    personInstance.doSomething(() => {
+      expect(Date.now() - time).toBeGreaterThan(280)
+      done()
+    })
+  })
+})