Aurelia unit testing access component's viewModel - unit-testing

Question

I am unit testing one of my components in an Aurelia project. I'd like to access my component's viewModel in my unit test but haven't had any luck so far.
I followed the example available at https://aurelia.io/docs/testing/components#manually-handling-lifecycle but I keep getting component.viewModel is undefined.
Here is the unit test:
describe.only('some basic tests', function() {
let component, user;
before(() => {
user = new User({ id: 100, first_name: "Bob", last_name: "Schmoe", email: 'joe#schmoe.com'});
user.save();
});
beforeEach( () => {
component = StageComponent
.withResources('modules/users/user')
.inView('<user></user>')
.boundTo( user );
});
it('check for ', () => {
return component.create(bootstrap)
.then(() => {
expect(2).to.equal(2);
return component.viewModel.activate({user: user});
});
});
it('can manually handle lifecycle', () => {
return component.manuallyHandleLifecycle().create(bootstrap)
.then(() => component.bind({user: user}))
.then(() => component.attached())
.then(() => component.unbind() )
.then(() => {
expect(component.viewModel.name).toBe(null);
return Promise.resolve(true);
});
});
afterEach( () => {
component.dispose();
});
});
Here is the error I get:
1) my aurelia tests
can manually handle lifecycle:
TypeError: Cannot read property 'name' of undefined
Here is the the line that defines the viewModel on the component object but only if aurelia.root.controllers.length is set. I am not sure how to set controllers in my aurelia code or if I need to do so at all.
I guess my question is:
How do I get access to a component's viewModel in my unit tests?

Answer 1

Edit #2:
I'd also like to point out that your own answer is essentially the same solution as the one I first proposed in the comments. It is the equivalent of directly instantiating your view model and not verifying whether the component is actually working.
Edit:
I tried this locally with a karma+webpack+mocha setup (as webpack is the popular choice nowadays) and there were a few caveats with getting this to work well. I'm not sure what the rest of your setup is, so I cannot tell you precisely where the error was (I could probably point this out if you told me more about your setup).
In any case, here's a working setup with karma+webpack+mocha that properly verifies the binding and rendering:
https://github.com/fkleuver/aurelia-karma-webpack-testing
The test code:
import './setup';
import { Greeter } from './../src/greeter';
import { bootstrap } from 'aurelia-bootstrapper';
import { StageComponent, ComponentTester } from 'aurelia-testing';
import { PLATFORM } from 'aurelia-framework';
import { assert } from 'chai';
describe('Greeter', () => {
let el: HTMLElement;
let tester: ComponentTester;
let sut: Greeter;
beforeEach(async () => {
tester = StageComponent
.withResources(PLATFORM.moduleName('greeter'))
.inView(`<greeter name.bind="name"></greeter>`)
.manuallyHandleLifecycle();
await tester.create(bootstrap);
el = <HTMLElement>tester.element;
sut = tester.viewModel;
});
it('binds correctly', async () => {
await tester.bind({ name: 'Bob' });
assert.equal(sut.name, 'Bob');
});
it('renders correctly', async () => {
await tester.bind({ name: 'Bob' });
await tester.attached();
assert.equal(el.innerText.trim(), 'Hello, Bob!');
});
});
greeter.html
<template>
Hello, ${name}!
</template>
greeter.ts
import { bindable } from 'aurelia-framework';
export class Greeter {
#bindable()
public name: string;
}
setup.ts
import 'aurelia-polyfills';
import 'aurelia-loader-webpack';
import { initialize } from 'aurelia-pal-browser';
initialize();
karma.conf.js
const { AureliaPlugin } = require('aurelia-webpack-plugin');
const { resolve } = require('path');
module.exports = function configure(config) {
const options = {
frameworks: ['source-map-support', 'mocha'],
files: ['test/**/*.ts'],
preprocessors: { ['test/**/*.ts']: ['webpack', 'sourcemap'] },
webpack: {
mode: 'development',
entry: { setup: './test/setup.ts' },
resolve: {
extensions: ['.ts', '.js'],
modules: [
resolve(__dirname, 'src'),
resolve(__dirname, 'node_modules')
]
},
devtool: 'inline-source-map',
module: {
rules: [{
test: /\.html$/i,
loader: 'html-loader'
}, {
test: /\.ts$/i,
loader: 'ts-loader',
exclude: /node_modules/
}]
},
plugins: [new AureliaPlugin()]
},
singleRun: false,
colors: true,
logLevel: config.browsers && config.browsers[0] === 'ChromeDebugging' ? config.LOG_DEBUG : config.LOG_INFO, // for troubleshooting mode
mime: { 'text/x-typescript': ['ts'] },
webpackMiddleware: { stats: 'errors-only' },
reporters: ['mocha'],
browsers: config.browsers || ['ChromeHeadless'],
customLaunchers: {
ChromeDebugging: {
base: 'Chrome',
flags: [ '--remote-debugging-port=9333' ]
}
}
};
config.set(options);
};
tsconfig.json
{
"compilerOptions": {
"experimentalDecorators": true,
"emitDecoratorMetadata": true,
"importHelpers": true,
"lib": ["es2018", "dom"],
"module": "esnext",
"moduleResolution": "node",
"sourceMap": true,
"target": "es2018"
},
"include": ["src"]
}
package.json
{
"scripts": {
"test": "karma start --browsers=ChromeHeadless"
},
"dependencies": {
"aurelia-bootstrapper": "^2.3.0",
"aurelia-loader-webpack": "^2.2.1"
},
"devDependencies": {
"#types/chai": "^4.1.6",
"#types/mocha": "^5.2.5",
"#types/node": "^10.12.0",
"aurelia-testing": "^1.0.0",
"aurelia-webpack-plugin": "^3.0.0",
"chai": "^4.2.0",
"html-loader": "^0.5.5",
"karma": "^3.1.1",
"karma-chrome-launcher": "^2.2.0",
"karma-mocha": "^1.3.0",
"karma-mocha-reporter": "^2.2.5",
"karma-source-map-support": "^1.3.0",
"karma-sourcemap-loader": "^0.3.7",
"karma-webpack": "^3.0.5",
"mocha": "^5.2.0",
"path": "^0.12.7",
"ts-loader": "^5.2.2",
"typescript": "^3.1.3",
"webpack": "^4.23.1",
"webpack-dev-server": "^3.1.10"
}
}
Original answer
If you're manually doing the lifecycle, you need to pass in a ViewModel yourself that it can bind to :)
I don't remember exactly what's strictly speaking needed so I'm quite sure there's some redundancy (e.g. one of the two bindingContexts passed in shouldn't be necessary). But this is the general idea:
const view = "<div>${msg}</div>";
const bindingContext = { msg: "foo" };
StageComponent
.withResources(resources/*optional*/)
.inView(view)
.boundTo(bindingContext)
.manuallyHandleLifecycle()
.create(bootstrap)
.then(component => {
component.bind(bindingContext);
}
.then(component => {
component.attached();
}
.then(component => {
expect(component.host.textContent).toEqual("foo");
}
.then(component => {
bindingContext.msg = "bar";
}
.then(component => {
expect(component.host.textContent).toEqual("bar");
};
Needless to say, since you create the view model yourself (the variable bindingContext in this example), you can simply access the variable you declared.

Answer 2

In order to get it to work, I had to use Container:
import { UserCard } from '../../src/modules/users/user-card';
import { Container } from 'aurelia-dependency-injection';
describe.only('some basic tests', function() {
let component, user;
before(() => {
user = new User({ id: 100, first_name: "Bob", last_name: "Schmoe", email: 'joe#schmoe.com'});
user.save();
});
beforeEach(() => {
container = new Container();
userCard = container.get( UserCard );
component = StageComponent
.withResources('modules/users/user-card')
.inView('<user-card></user-card>')
.boundTo( user );
});
it('check for ', () => {
return component.create(bootstrap)
.then(() => {
expect(2).to.equal(2);
return userCard.activate({user: user});
});
});
});