stub-azure-function-context

stub-azure-function-context

Aims to implement the context object as described on the Azure Functions JavaScript Developer Guide.

By default the behaviour assumes a req HTTP trigger and a res HTTP output, but if you have more exotic config, then you can set that up!

NB: if you follow the "ordered argument" pattern then you'll need to define the triggers/outputs in the same order as in your function.json.

If your function under test does not call context.done, then your test will time out. This is intended functionality so that you can find cases where you don't return back to the Function Runtime.

stubContext resolves with an object containing:

{
    context: context, // the actual stubbed context object after your function manipulates it
    err: null|Error,  // any error you passed to context.done, like: context.done(new Error("Oops"))
    propertyBag: {},  // an object of any overrides you want to make on your outputs
}

Logging goes out to console. Only the methods defined in the developer guide are mentioned:

• error
• warn
• info
• verbose

None of that silly stuff ;-)

Usage examples:

const { stubContext } = require('stub-azure-function-context');

const functionToTest = require('../function-under-test');

describe('app code', () => {
	it('returns 200', async () => {
	    const { context, err, propertyBag, } = await stubContext(functionToTest);
	    expect(context).to.have.nested.property('res.status', 200);
	});
	it('returns 200 in promise/a+ style', (done) => {
		stubContext(functionToTest)
			.then(({ context, err, propertyBag }) => {
				expect(context).to.have.nested.property('res.status', 200);
				done();
			})
			.catch(done);
	});
	it('change trigger values before calling your function under test', async () => {
		const { context } = await stubContext((context, req, ...otherTriggers) => {
		    req.body = { 'helpful': 'test object' };
		    return functionToTest(context, req, ...otherTriggers);
		});
		expect(context).to.have.nested.property('res.body.helpful', 'test object');
	});
});