fix: spy statistics is not reset after restore (#55)

index.d.ts

@@ -38,6 +38,11 @@ declare namespace mm {
    */
   function empty(mod: any, method: string, timeout?: number): MockMate;
 
+  /**
+   * spy a function
+   */
+  function spy(mod: any, method: string): void;
+
   /**
    * mock return callback(null, data1, data2).
    */

lib/mm.js

@@ -224,7 +224,11 @@ exports.empty = function(mod, method, timeout) {
  */
 exports.spy = function(mod, method) {
   if (typeof mod[method] !== 'function') throw new Error(`spy target ${method} is not a function`);
-  mock(mod, method, mod[method]);
+  const originalFn = mod[method];
+  const wrap = function proxy() {
+    return originalFn.apply(this, arguments);
+  };
+  mock(mod, method, wrap);
 };
 
 /**

test/mm.test.js

@@ -1125,8 +1125,24 @@ describe('test/mm.test.js', () => {
       target.add.calledArguments.should.eql([[ 1, 1 ], [ 2, 2 ]]);
       target.add.lastCalledArguments.should.eql([ 2, 2 ]);
     });
-  });
 
+    it('should reset spy statistics after restore', () => {
+      const target = {
+        add(a, b) {
+          return a + b;
+        },
+      };
+      mm.spy(target, 'add');
+      target.add(1, 1);
+      target.add.called.should.equal(1);
+      target.add.calledArguments.should.eql([[ 1, 1 ]]);
+      target.add.lastCalledArguments.should.eql([ 1, 1 ]);
+      mm.restore();
+      assert.strictEqual(target.add.called, undefined);
+      assert.strictEqual(target.add.calledArguments, undefined);
+      assert.strictEqual(target.add.lastCalledArguments, undefined);
+    });
+  });
 });
 
 const enable = require('enable');