walkthrough.md

Setup & debugging walkthrough

This procedure uses the VS Code Functions extension to create Azure Functions.

To set up your environment, initialize a new Node.js app in an empty folder by running npm init.

npm init -y

Next, install Mocha by running the following command:

npm i mocha chai sinon

Now update package.json to replace the existing test command with the following command:

"scripts": {
    "test": "mocha --recursive '**/tests/*'"
}

Create test modules

With the project initialized, you can create the modules used to run the automated tests.

Begin by creating a new function using the VS Code Functions extension to create a new JavaScript HTTP Function and name it HttpTrigger. Create new folders named testing and test to hold the support modules & test cases.

In the testing folder add a new file, name it defaultContext.js, and add the following code:

var sinon = require('sinon');
module.exports = {
    log: sinon.stub()
};

This module mocks the log function to represent the default execution context.

In the tests folder create a new file named index.test.js and add the following code:

let chai = require('chai');
const httpFunction = require('./index');
const context = require('../testing/defaultContext')
let expect = chai.expect;

it('Http trigger should return known text', async () => {

    const request = {
        query: { name: 'Bill' }
    };

    await httpFunction(context, request);

    expect(context.log.callCount).to.equal(1);
    expect(context.res.body).toEqual('Hello Bill');
});

The HTTP function from the template returns a string of "Hello" concatenated with the name provided in the query string. This test creates a fake instance of a request and passes it to the HTTP function. The test checks that the log method is called once and the returned text equals "Hello Bill".

Next, use the VS Code Functions extension to create a new JavaScript Timer function and name it TimerTrigger. Once the function is created, add new folders testing and tests.

In the testing folder add 2 new files named defaultContext.js and defaultTimer.js.

In defaultContext.js add the following code:

var sinon = require('sinon');
module.exports = {
    log: sinon.stub()
};

and in defaultTimer.js add the following code:

module.exports = {
    IsPastDue: false
};

This module implements the IsPastDue property to stand is as a fake timer instance. Timer configurations like NCRONTAB expressions are not required here as the test harness is simply calling the function directly to test the outcome.

Now create a new file in the tests folder named index.test.js, and add the following code:

let chai = require('chai');
const timerFunction = require('./index');
const context = require('../testing/defaultContext');
const timer = require('../testing/defaultTimer');
let expect = chai.expect;
it('Timer trigger should log message', () => {
    timerFunction(context, timer);
    expect(context.log.callCount).to.equal(1);
});

The timer function from the template logs a message at the end of the body of the function. This test ensures the log function is called once.

Run tests

To run the tests, press **CTRL + ~** to open the command window, and run npm test:

npm test

Debug tests

To debug your tests, add the following configuration to your launch.json file:

{
    "type": "node",
    "request": "launch",
    "name": "Mocha Tests",
    "program": "${workspaceFolder}/node_modules/mocha/bin/_mocha",
    "args": 
    [
        "--timeout",
        "999999",
        "--colors",
        "'${workspaceFolder}/{,!(node_modules)/}*/*.test.js'"
    ],
  "internalConsoleOptions": "openOnSessionStart"
}

Next, set a breakpoint in your test and press F5.