Merge branch 'master' of https://github.com/sdgluck/mewt

sdgluck · Mar 29, 2017 · 2529eb4 · 2529eb4
2 parents 8def3e9 + 874c5e4
commit 2529eb4
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Showing 3 changed files with 38 additions and 7 deletions.
diff --git a/index.js b/index.js
@@ -3,10 +3,15 @@ function mewt(target) {
   const multiRet = 'push pop shift unshift'
   const mutArrMethods = 'reverse sort splice fill copyWithin'
   const nonMutArrMethods = 'filter map concat slice'
-
+  const mutationTraps = ['setPrototypeOf', 'defineProperty', 'deleteProperty']
+
   const isA = Array.isArray(target)
   const clone = isA ? v => [...v] : v => Object.assign({}, v)
 
+  const mutationTrapError = (isA) => {
+    throw new Error(`${isA ? 'array' : 'object'} is immutable`)
+  }
+
   const override = prop => (...args) => {
     const mutMethod = mutArrMethods.includes(prop)
     const nonMutMethod = nonMutArrMethods.includes(prop)
@@ -35,14 +40,17 @@ function mewt(target) {
     throw new Error('mewt accepts array or object')
   }
 
-  return new Proxy(target, {
-    set () {
-      throw new Error(`${isA ? 'array' : 'object'} is immutable`)
-    },
-    get (_, prop) {
+  let proxyHandler = {
+    get: (_, prop) => {
       return api[prop] || target[prop] && ({}.hasOwnProperty.call(target, prop) ? target[prop] : override(prop))
     }
+  }
+
+  mutationTraps.forEach((key) => {
+    proxyHandler[key] = mutationTrapError
   })
+
+  return new Proxy(target, proxyHandler)
 }
 
 module.exports = mewt
diff --git a/lib/index.js b/lib/index.js
diff --git a/test.js b/test.js
@@ -205,6 +205,29 @@ describe('mewt', () => {
       expect(() => o.track = 'The Promise').toThrowError(/immutable/)
     })
 
+    it('should throw on Object.defineProperty', () => {
+      const o = mewt({})
+      expect(() => {
+        Object.defineProperty(o, 'foo', {
+          value: 'bar'
+        })
+      }).toThrowError(/immutable/)
+    })
+
+    it('should throw on delete', () => {
+      const o = mewt({})
+      expect(() => {
+        delete o.foo
+      }).toThrowError(/immutable/)
+    })
+
+    it('should throw on setPrototypeOf', () => {
+      const o = mewt({})
+      expect(() => {
+        Object.setPrototypeOf(o, {bar: 'baz'})
+      }).toThrowError(/immutable/)
+    })    
+
     it('should have $set & $unset', () => {
       const o = mewt({})
       assertMewt(o)