Callback Module

app.js

var express = require('express'),
    app = express(),
    port = process.env.PORT || 3030,
    myModule = require('./myModule')
;

app.use(express.static(__dirname + '/public'));

app.get('/', function(request, response, next) {
    myModule("Hello World", function(error, result) {
        if (error) {
            response.status(400).json(error);
        } else {
            response.json(result);
        }
    });
});

app.listen(port, function(){
  console.log('Listening on port ' + port);
});

module.exports = app;

myModule.js

module.exports = function(options, callback) {
    if (!options) {
        options = {
            text: "It Works"
        };
    }
    setTimeout(function() {
        try {
            var thisString = options.text || options;
            if (typeof thisString == "string") {
                callback(undefined, thisString);
            } else {
                callback(new Error("value is not a string"), undefined);
            }
        } catch (error) {
            callback(error, undefined);
        }
    }, getRandomInt(50,800));
}

function getRandomInt(min, max) {
  return Math.floor(Math.random() * (max - min)) + min;
}

test.js

var request = require('supertest'),
    app = require('./app'),
    myModule = require('./myModule'),
    defaultString = "It Works",
    testString = "This is my Test String"
;

describe("the Server", function() {
    it("starts", function(done) {
        request(app)
            .get("/")
            .expect(200)
            .end(done)
        ;
    });
});

describe("middleware", function() {
    it("returns the default string", function(done) {
        myModule(null, function callback(error, result) {
            if (error) {
                throw error;
            }
            if (result != defaultString) {
                throw new Error("Expected String to Be ["+defaultString+"], Got ["+result+"]");
            }
            done();
        });
    });

    it("returns the test string", function(done) {
        myModule(testString, function callback(error, result) {
            if (error) {
                throw error;
            }
            if (result != testString) {
                throw new Error("Expected String to Be ["+testString+"], Got ["+result+"]");
            }
            done();
        });
    });

    it("returns the test string in dot notation", function(done) {
        myModule({text: testString}, function callback(error, result) {
            if (error) {
                throw error;
            }
            if (result != testString) {
                throw new Error("Expected String to Be ["+testString+"], Got ["+result+"]");
            }
            done();
        });
    });

    it ("errors when an array is passed", function(done) {
        myModule([1,2,3,4,5], function callback(error, result) {
            if (!error) {
                throw new Error("Expect an error");
            }
            done();
        });
    });

    it ("errors when an array is passed in dot notation", function(done) {
        myModule({text: [1,2,3,4,5]}, function callback(error, result) {
            if (!error) {
                throw new Error("Expect an error");
            }
            done();
        });
    });
});