Should not try to attach to modules that export primitives

lib/getDefinePropertySrc.js

@@ -11,9 +11,10 @@ var srcs = {
 };
 
 function getDefinePropertySrc() {
-    var src;
+    var src = "if (typeof(module.exports) === 'function' || \n" +
+            "(typeof(module.exports) === 'object' && module.exports !== null && Object.isExtensible(module.exports))) {\n";
 
-    src = Object.keys(srcs).reduce(function forEachSrc(preValue, value) {
+    src += Object.keys(srcs).reduce(function forEachSrc(preValue, value) {
         return preValue += "Object.defineProperty(module.exports, '" +
             value +
             "', {enumerable: false, value: " +
@@ -22,6 +23,8 @@ function getDefinePropertySrc() {
             "writable: true}); ";
     }, "");
 
+    src += "\n}";
+
     return src;
 }
 

testLib/boolean.js

@@ -0,0 +1 @@
+module.exports = true;

testLib/null.js

@@ -0,0 +1 @@
+module.exports = null;

testLib/sealedObject.js

@@ -0,0 +1,4 @@
+var obj = {};
+Object.seal(obj);
+
+module.exports = obj;

testLib/sharedTestCases.js

@@ -220,6 +220,24 @@ describe("rewire " + (typeof testEnv === "undefined"? "(node)": "(" + testEnv +
         expect(rewired.__get__("someVar")).to.be("hello");
     });
 
+    it("should not be a problem to have a module that exports a boolean", function() {
+        expect(function() {
+            var rewired = rewire("./boolean.js");
+        }).to.not.throwException();
+    });
+
+    it("should not be a problem to have a module that exports null", function() {
+        expect(function() {
+            var rewired = rewire("./null.js");
+        }).to.not.throwException();
+    });
+
+    it("should not be a problem to have a module that exports a sealed object", function() {
+        expect(function() {
+            var rewired = rewire("./sealedObject.js");
+        }).to.not.throwException();
+    });
+
     it("should not influence the original require if nothing has been required within the rewired module", function () {
         rewire("./emptyModule.js"); // nothing happens here because emptyModule doesn't require anything
         expect(require("./moduleA.js").__set__).to.be(undefined); // if restoring the original node require didn't worked, the module would have a setter