Add possibility to mock undefined, implicit globals

Fixes jhnns#35

Author: jhnns

lib/__set__.js

@@ -25,15 +25,27 @@ function __set__() {
             if (arguments.env.hasOwnProperty(arguments.varName)) {
                 arguments.varValue = arguments.env[arguments.varName];
                 arguments.src += arguments.varName + " = arguments.env[" + JSON.stringify(arguments.varName) + "]; ";
-                arguments.revertArgs[0][arguments.varName] = eval(arguments.varName);
+                try {
+                    // Allow tests to mock implicit globals
+                    // @see https://github.com/jhnns/rewire/issues/35
+                    arguments.revertArgs[0][arguments.varName] = eval(arguments.varName);
+                } catch (err) {
+                    arguments.revertArgs[0][arguments.varName] = undefined;
+                }
             }
         }
     } else if (typeof arguments.varName === "string" && arguments.length === 2) {
         if (!arguments.varName) {
             throw new TypeError("__set__ expects a non-empty string as a variable name");
         }
         arguments.src = arguments.varName + " = arguments.varValue;";
-        arguments.revertArgs = [arguments.varName, eval(arguments.varName)];
+        try {
+            // Allow tests to mock implicit globals
+            // @see https://github.com/jhnns/rewire/issues/35
+            arguments.revertArgs = [arguments.varName, eval(arguments.varName)];
+        } catch (err) {
+            arguments.revertArgs = [arguments.varName, undefined];
+        }
     } else {
         throw new TypeError("__set__ expects an environment object or a non-empty string as a variable name");
     }

test/testModules/implicitGlobal.js

@@ -1,2 +1,6 @@
 implicitGlobal = "this is an implicit global var ..." +
-    "yes, it's bad coding style but there are still some libs out there";
+    "yes, it's bad coding style but there are still some libs out there";
+
+module.exports = function () {
+    return undefinedImplicitGlobal;
+};

test/testModules/sharedTestCases.js

@@ -249,16 +249,28 @@ describe("rewire " + (typeof testEnv === "undefined"? "(node)": "(" + testEnv +
     });
 
     it("should be possible to set implicit globals", function () {
-        var implicitGlobalModule = rewire("./implicitGlobal.js");
+        var implicitGlobalModule,
+            err;
 
-        implicitGlobalModule.__set__("implicitGlobal", true);
-        expect(implicitGlobalModule.__get__("implicitGlobal")).to.be(true);
-        // 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");
+        try {
+            implicitGlobalModule = rewire("./implicitGlobal.js");
+
+            implicitGlobalModule.__set__("implicitGlobal", true);
+            expect(implicitGlobalModule.__get__("implicitGlobal")).to.be(true);
+            // 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");
+        } catch (e) {
+            err = e;
+        } finally {
+            // Cleaning up...
+            delete global.implicitGlobal;
+            delete global.undefinedImplicitGlobal;
+        }
 
-        // Cleaning up...
-        delete global.implicitGlobal;
+        if (err) {
+            throw err;
+        }
     });
 
     it("should throw a TypeError if the path is not a string", function () {
@@ -298,4 +310,31 @@ describe("rewire " + (typeof testEnv === "undefined"? "(node)": "(" + testEnv +
 
     });
 
+    it("should be possible to mock undefined, implicit globals", function () {
+        var implicitGlobalModule,
+            err;
+
+        try {
+            implicitGlobalModule = rewire("./implicitGlobal.js");
+            implicitGlobalModule.__set__("undefinedImplicitGlobal", "yoo!");
+            expect(implicitGlobalModule.__get__("undefinedImplicitGlobal")).to.equal("yoo!");
+
+            implicitGlobalModule = rewire("./implicitGlobal.js");
+            implicitGlobalModule.__set__({
+                undefinedImplicitGlobal: "bro!"
+            });
+            expect(implicitGlobalModule.__get__("undefinedImplicitGlobal")).to.equal("bro!");
+        } catch (e) {
+            err = e;
+        } finally {
+            // Cleaning up...
+            delete global.implicitGlobal;
+            delete global.undefinedImplicitGlobal;
+        }
+
+        if (err) {
+            throw err;
+        }
+    });
+
 });