All of the code used in this example is located in the /chapter-09-node/testing-example folder. The code and corresponding tests are very simple and are not representative of real-world applications, but they're intended to demonstrate how to use Jest for testing. The following code represents the file structure of the /testing-example folder:

├── /src
|    ├── /__tests__
|    │    └── main.test.js
|    └── main.c
├── package.json
└── package-lock.json

The contents of the C file that we'll test, /src/main.c, is shown as follows:

int addTwoNumbers(int leftValue, int rightValue) {
    return leftValue + rightValue;
}

float divideTwoNumbers(float leftValue, float rightValue) {
    return leftValue / rightValue;
}

double findFactorial(float value) {
    int i;
    double factorial = 1;
    
    for (i = 1; i <= value; i++) {
        factorial = factorial * i;
    }
    return factorial;
}

All three functions in the file are performing simple mathematical operations. The package.json file includes a script to compile the C file to a Wasm file for testing. Run the following command to compile the C file:

npm run build

There should be a file named main.wasm in the /src directory. Let's move on to describing the testing configuration step.