Using Sinon+Rewire for Unit Testing with Private Methods
How many times have you tried to follow good programming practices by creating well-defined, single-purposed methods and only exposing the necessary public methods outside of your library and become frustrated with attempting to write unit tests for your code? You then begin to question your decisions about which method(s) should be `public` and which methods should be `private`. Additionally, you start to wonder if 100% code coverage is truly necessary. I mean, 75% of code coverage isn't really that bad, is it? It's better than 10%, right?
If you scour the web for suggestions, there's a number of less-than-optimal solutions for this problem. First, I'd like to cover some of these solutions and why they are less than ideal. Second, I'll provide some production code that contains a private method along with how to successfully achieve 100% coverage with unit tests. The examples provided are in Node.js.
IoT Asset Management Starter Kit
First demonstrated at Microsoft's 2016 Ignite Conference in Atlanta, GA, the IoT Asset Management Starter Kit is a boiler plate project comprised of Node.js and Angular 2 that facilitates the quick development of an IoT project for Asset Management. The project brings all the necessary components - Azure IoT Hub, Stream Analytics, Heroku, MongoDB and Raspberry Pi 3 - together to build a working end-to-end IoT solution.
Karma + Jasmine + Visual Studio (including Visual Studio Code)
I've been developing a LOT of Angular applications lately. Some of them are hybrid projects (Angular w/ MVC); some of my projects have been completely separated (Angular for client-side, with a separate project for an API). Regardless, I always want to ensure that my code has been thoroughly tested with unit tests and acceptance (E2E) tests. When developing hybrid projects, my preferred IDE is Visual Studio. When developing a pure, client-side project, my preferred IDE is Visual Studio Code as it has a lot less remnants/artifacts tied to a solution (.vs, .xproj, .csproj, etc.) eliminating the need for a ridiculously large .gitignore file. Additionally, I will use WebStorm depending on the need.
Jasmine is a great framework for providing both unit testing and end-to-end, acceptance testing. Coupled with Karma, Jasmine can monitor file changes to our client-side code and execute tests on every file change in order to ensure that all tests are always passing. In this blog post, I will demonstrate how to set up and use Karma and Jasmine in both development environments.
'Hello World' with Node.js and Visual Studio Code
As I've shared in other posts, I like trying new things. One new thing I've been working with over the past couple of weeks is Visual Studio Code (VSC) - a lightweight editor from Microsoft that recognizes and offers IntelliSense for many different file formats. Unlike the commercial or even community editions of Visual Studio, VSC is not solution- or project-based. Instead, VSC is based on directory structures.
For those of you interested in building native JavaScript applications using Node.js, I wanted to provide a demo in how to accomplish this using Visual Studio Code. While full versions of Visual Studio do support Node.js applications, it can sometimes be overkill, especially if you're not needing pre-compiled libraries based on the .NET Framework (VSC does support referencing external libraries and compilation with MSBuild, but then we get into the discussion of should we use VSC vs. Visual Studio, which is not the point of this blog post). Again, the demonstration below is to assist you as you look to build native JavaScript applications.
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