sharedTestCases.js

// Don't run code in ES5 strict mode.
// In case this module was in strict mode, all other modules called by this would also be strict.
// But when testing if the strict mode is preserved, we must ensure that this module is NOT strict.

// These shared test cases are used to check if the provided implementation of rewire is compatible
// with the original rewire. Since you can use rewire with client-side bundlers like webpack we need
// to test the implementation there again.
// @see https://github.com/jhnns/rewire-webpack

var expect = require("expect.js"),
    rewire = require("rewire"),
    __set__Src = require("../lib/__set__.js").toString(),
    __get__Src = require("../lib/__get__.js").toString(),
    __with__Src = require("../lib/__with__.js").toString();

var supportsObjectSpread = (function () {
    try {
        eval("({...{}})");
        return true;
    } catch (err) {
        return false;
    }
})();
var supportsObjectRest = (function () {
    try {
        eval("const {...a} = {}");
        return true;
    } catch (err) {
        return false;
    }
})();

function checkForTypeError(err) {
    expect(err.constructor).to.be(TypeError);
}

module.exports = function () {

    it("should work like require()", function () {
        rewire("./moduleA.js").getFilename();
        require("./moduleA.js").getFilename();
        expect(rewire("./moduleA.js").getFilename()).to.eql(require("./moduleA.js").getFilename());
        expect(rewire("../testLib/someOtherModule.js").filename).to.eql(require("../testLib/someOtherModule.js").filename);
    });

    it("should return a fresh instance of the module", function () {
        var someOtherModule = require("./someOtherModule.js"),
            rewiredSomeOtherModule;

        someOtherModule.fs = "This has been modified";
        rewiredSomeOtherModule = rewire("./someOtherModule.js");
        expect(rewiredSomeOtherModule.fs).not.to.be("This has been modified");
    });

    it("should not cache the rewired module", function () {
        var rewired,
            someOtherModule = require("./someOtherModule.js");

        someOtherModule.fs = "This has been changed";

        rewired = rewire("./someOtherModule.js");
        expect(someOtherModule).not.to.be(rewired);
        expect(require("./moduleA.js").someOtherModule).not.to.be(rewired);
        expect(require("./moduleA.js").someOtherModule).to.be(someOtherModule);
        expect(require("./moduleA.js").someOtherModule.fs).to.be("This has been changed");
    });

    // By comparing the src we can ensure that the provided __set__ function is our tested implementation
    it("should modify the module so it provides the __set__ - function", function () {
        expect(rewire("./moduleA.js").__set__.toString()).to.be(__set__Src);
        expect(rewire("./moduleB.js").__set__.toString()).to.be(__set__Src);
    });

    // By comparing the src we can ensure that the provided __set__ function is our tested implementation
    it("should modify the module so it provides the __get__ - function", function () {
        expect(rewire("./moduleA.js").__get__.toString()).to.be(__get__Src);
        expect(rewire("./moduleB.js").__get__.toString()).to.be(__get__Src);
    });

    // By comparing the src we can ensure that the provided __set__ function is our tested implementation
    it("should modify the module so it provides the __with__ - function", function () {
        expect(rewire("./moduleA.js").__with__.toString()).to.be(__with__Src);
        expect(rewire("./moduleB.js").__with__.toString()).to.be(__with__Src);
    });


    ["__get__", "__set__", "__with__"].forEach(function(funcName) {
        it("should provide " + funcName + " as a non-enumerable property", function () {
            expect(Object.keys(rewire("./moduleA.js")).indexOf(funcName)).to.be(-1);
        });

        it("should provide " + funcName + " as a writable property", function () {
            var obj = rewire("./moduleA.js");
            var desc = Object.getOwnPropertyDescriptor(obj, funcName);
            expect(desc.writable).to.be(true);
        });
    });

    it("should not influence other modules", function () {
        rewire("./moduleA.js");

        expect(require("./someOtherModule.js").__set__).to.be(undefined);
        expect(require("./someOtherModule.js").__get__).to.be(undefined);
        expect(require("./someOtherModule.js").__with__).to.be(undefined);
    });

    it("should not override/influence global objects by default", function () {
        // This should throw no exception
        rewire("./moduleA.js").checkSomeGlobals();
        rewire("./moduleB.js").checkSomeGlobals();
    });

    // This is just an integration test for the __set__ method
    // You can find a full test for __set__ under /test/__set__.test.js
    it("should provide a working __set__ method", function () {
        var rewiredModuleA = rewire("./moduleA.js"),
            newObj = {};

        expect(rewiredModuleA.getMyNumber()).to.be(0);
        rewiredModuleA.__set__("myNumber", 2);
        expect(rewiredModuleA.getMyNumber()).to.be(2);
        rewiredModuleA.__set__("myObj", newObj);
        expect(rewiredModuleA.getMyObj()).to.be(newObj);
        rewiredModuleA.__set__("env", "ENVENV");
    });

    // This is just an integration test for the __get__ method
    // You can find a full test for __get__ under /test/__get__.test.js
    it("should provide a working __get__ method", function () {
        var rewiredModuleA = rewire("./moduleA.js");

        expect(rewiredModuleA.__get__("myNumber")).to.be(rewiredModuleA.getMyNumber());
        expect(rewiredModuleA.__get__("myObj")).to.be(rewiredModuleA.getMyObj());
    });

    // This is just an integration test for the __with__ method
    // You can find a full test for __with__ under /test/__with__.test.js
    it("should provide a working __with__ method", function () {
        var rewiredModuleA = rewire("./moduleA.js"),
            newObj = {};

        expect(rewiredModuleA.getMyNumber()).to.be(0);
        expect(rewiredModuleA.getMyObj()).to.not.be(newObj);

        rewiredModuleA.__with__({
            myNumber: 2,
            myObj: newObj
        })(function () {
            expect(rewiredModuleA.getMyNumber()).to.be(2);
            expect(rewiredModuleA.getMyObj()).to.be(newObj);
        });

        expect(rewiredModuleA.getMyNumber()).to.be(0);
        expect(rewiredModuleA.getMyObj()).to.not.be(newObj);
    });

    it("should provide the ability to inject mocks", function (done) {
        var rewiredModuleA = rewire("./moduleA.js"),
            mockedFs = {
                readFileSync: function (file) {
                    expect(file).to.be("bla.txt");
                    done();
                }
            };

        rewiredModuleA.__set__("fs", mockedFs);
        rewiredModuleA.readFileSync();
    });

    it("should not influence other modules when injecting mocks", function () {
        var rewiredModuleA = rewire("./moduleA.js"),
            someOtherModule,
            mockedFs = {};

        rewiredModuleA.__set__("fs", mockedFs);
        someOtherModule = require("./someOtherModule.js");
        expect(someOtherModule.fs).not.to.be(mockedFs);
    });

    it("should provide the ability to mock global objects just within the module", function () {
        var rewiredModuleA = rewire("./moduleA.js"),
            rewiredModuleB = rewire("./moduleB.js"),
            consoleMock = {},
            bufferMock = {},
            documentMock = {},
            newFilename = "myFile.js";

        rewiredModuleA.__set__({
            console: consoleMock,
            __filename: newFilename
        });
        expect(rewiredModuleA.getConsole()).to.be(consoleMock);
        expect(rewiredModuleB.getConsole()).not.to.be(consoleMock);
        expect(console).not.to.be(consoleMock);
        expect(rewiredModuleA.getFilename()).to.be(newFilename);
        expect(rewiredModuleB.getFilename()).not.to.be(newFilename);
        expect(console).not.to.be(newFilename);
        if (typeof window === "undefined") {
            rewiredModuleA.__set__("Buffer", bufferMock);
            expect(rewiredModuleA.getBuffer()).to.be(bufferMock);
            expect(rewiredModuleB.getBuffer()).not.to.be(bufferMock);
            expect(Buffer).not.to.be(bufferMock);
        } else {
            rewiredModuleA.__set__("document", documentMock);
            expect(rewiredModuleA.getDocument()).to.be(documentMock);
            expect(rewiredModuleB.getDocument() === documentMock).to.be(false);
            expect(document === documentMock).to.be(false);
        }
    });

    it("should be possible to mock global objects that are added on runtime", function () {
        var rewiredModule;

        if (typeof window === "undefined") {
            global.someGlobalVar = "test";
            rewiredModule = rewire("./moduleA.js");
            rewiredModule.__set__("someGlobalVar", "other value");
            expect(global.someGlobalVar).to.be("test");
            expect(rewiredModule.__get__("someGlobalVar")).to.be("other value");
            delete global.someGlobalVar;
        } else {
            window.someGlobalVar = "test";
            rewiredModule = rewire("./moduleA.js");
            rewiredModule.__set__("someGlobalVar", "other value");
            expect(window.someGlobalVar).to.be("test");
            expect(rewiredModule.__get__("someGlobalVar")).to.be("other value");
            if (typeof navigator !== "undefined" && /MSIE [6-8]\.[0-9]/g.test(navigator.userAgent) === false) {
                delete window.someGlobalVar;
            }
        }
    });

    it("should not be a problem to have a comment on file end", function () {
        var rewired = rewire("./emptyModule.js");

        rewired.__set__("someVar", "hello");
        expect(rewired.__get__("someVar")).to.be("hello");
    });

    it("should not be a problem to have a module that exports a boolean", function( ) {
        rewire("./boolean.js"); // should not throw
    });

    it("should not be a problem to have a module that exports null", function () {
        rewire("./null.js"); // should not throw
    });

    it("should not be a problem to have a module that exports a sealed object", function () {
        rewire("./sealedObject.js"); // should not throw
    });

    (supportsObjectSpread ? it : it.skip)("should not be a problem to have a module that uses object spread operator", function () {
        rewire("./objectSpreadOperator.js"); // should not throw
    });

    (supportsObjectRest ? it : it.skip)("should not be a problem to have a module that uses object rest operator", function () {
        rewire("./objectRestOperator.js"); // should not throw
    });

    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
    });

    it("subsequent calls of rewire should always return a new instance", function () {
        expect(rewire("./moduleA.js")).not.to.be(rewire("./moduleA.js"));
    });

    it("should preserve the strict mode", function () {
        var strictModule = rewire("./strictModule.js");

        expect(function () {
            strictModule.doSomethingUnstrict();
        }).to.throwException(checkForTypeError);
    });

    it("should not modify line numbers in stack traces", function () {
        var throwError = rewire("./throwError.js");

        try {
            throwError();
        } catch (err) {
            expect(err.stack.split("\n")[1]).to.match(/:6:26/);
        }
    });

    it("should be possible to set implicit globals", function () {
        var implicitGlobalModule,
            err;

        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;
        }

        if (err) {
            throw err;
        }
    });

    it("should throw a TypeError if the path is not a string", function () {
        expect(function () {
            rewire(null);
        }).to.throwException(checkForTypeError);
    });

    it("should also revert nested changes (with dot notation)", function () {
        var rewiredModuleA = rewire("./moduleA.js"),
            revert;

        revert = rewiredModuleA.__set__("myObj.test", true);
        expect(rewiredModuleA.getMyObj()).to.eql({
            test: true
        });
        revert();
        // This test also demonstrates a known drawback of the current implementation
        // If the value doesn't exist at the time it is about to be set, it will be
        // reverted to undefined instead deleting it from the object
        // However, this is probably not a real world use-case because why would you
        // want to mock something when it is not set.
        expect(rewiredModuleA.getMyObj()).to.eql({
            test: undefined
        });

        revert = rewiredModuleA.__set__({
            "myObj.test": true
        });
        expect(rewiredModuleA.getMyObj()).to.eql({
            test: true
        });
        revert();
        expect(rewiredModuleA.getMyObj()).to.eql({
            test: undefined
        });

    });

    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;
        }
    });

    it("should be possible to mock and revert JSON.parse (see #40)", function () {
        var moduleA = rewire("./moduleA.js"),
            revert;

        revert = moduleA.__set__({
            JSON: {
                parse: function () { return true; }
            }
        });

        revert();
    });

    it("should be possible to set a const variable", function () {
        var constModule = rewire("./constModule");

        "abcdefghij".split("").forEach(letter => {
            constModule.__set__(letter, "this has been changed"); // should not throw
            expect(constModule[letter]()).to.equal("this has been changed");
        });
    });

    it("should fail with a helpful TypeError when const is re-assigned", function () {
        expect(function () {
            rewire("./wrongConstModule");
        }).to.throwException(/^Assignment to constant variable at .+?wrongConstModule\.js:4:1$/);
    });

};