fix: conserve fn.length and fn.name (#79)

packages/hooks/src/hooks.ts

@@ -2,7 +2,7 @@ import { compose, Middleware } from './compose';
 import {
   HookContext, setManager, HookContextData, HookOptions, convertOptions, setMiddleware
 } from './base';
-import { copyProperties } from './utils';
+import { copyFnProperties, copyProperties } from './utils';
 
 export function getOriginal (fn: any): any {
   return typeof fn.original === 'function' ? getOriginal(fn.original) : fn;
@@ -51,6 +51,7 @@ export function functionHooks <F> (fn: F, managerOrMiddleware: HookOptions) {
     return compose(hookChain).call(this, context);
   };
 
+  copyFnProperties(wrapper, fn);
   copyProperties(wrapper, fn);
   setManager(wrapper, manager);
 

packages/hooks/src/utils.ts

@@ -45,3 +45,19 @@ export function copyProperties <F> (target: F, ...originals: any[]) {
 
   return target;
 }
+
+export function copyFnProperties <F> (target: F, original : any) {
+  const internalProps = ['name', 'length'];
+
+  try {
+    for (const prop of internalProps) {
+      const value = original[prop];
+
+      Object.defineProperty(target, prop, { value });
+    }
+  } catch (e) {
+    // Avoid IE error
+  }
+
+  return target;
+}

packages/hooks/test/function.test.ts

@@ -28,6 +28,13 @@ describe('functionHooks', () => {
     assert.ok(getManager(fn) !== null);
   });
 
+  it('conserve name and length properties', () => {
+    const fn = hooks(hello, []);
+
+    assert.strictEqual(fn.length, hello.length);
+    assert.strictEqual(fn.name, hello.name);
+  });
+
   it('throws an error with non function', () => {
     assert.throws(() => functionHooks({}, middleware([])));
   })