Use mocha to check for global leaks

package.json

@@ -33,7 +33,7 @@
     "mocha": "^2.1.0"
   },
   "scripts": {
-    "test": "node node_modules/mocha/bin/mocha -R spec",
+    "test": "mocha -R spec --check-leaks",
     "coverage": "istanbul cover ./node_modules/mocha/bin/_mocha"
   }
 }

test/rewire.test.js

@@ -16,14 +16,6 @@ describe("rewire", function () {
             fs.renameSync(fakeNodeModules, path.resolve(__dirname, "testModules/node_modules"));
         }
     });
-    it("should keep not leak globals", function () {
-        // This test should run first, as the global space may be already polluted if 
-        //   require("../") is run before this test.
-        var originalGlobalKeys = Object.keys(global),
-            rewire = require("../"),
-            emptyModule = rewire("./testModules/emptyModule.js");
-        expect(Object.keys(global)).to.eql(originalGlobalKeys);
-    });
     it("should pass all shared test cases", function () {
         require("./testModules/sharedTestCases.js");
     });

test/testModules/sharedTestCases.js

@@ -256,6 +256,9 @@ describe("rewire " + (typeof testEnv === "undefined"? "(node)": "(" + testEnv +
         // setting implicit global vars will change them globally instead of locally.
         // that's a shortcoming of the current implementation which can't be solved easily.
         //expect(implicitGlobal).to.be.a("string");
+
+        // Cleaning up...
+        delete global.implicitGlobal;
     });
 
     it("should throw a TypeError if the path is not a string", function () {