Unit Testing

Alsatian

Alsatian is a unit testing framework written in TypeScript. It allows for usage of Test Cases, and outputs TAP-compliant markup.

To use it, install it from npm:

npm install alsatian --save-dev

Then set up a test file:

import { Expect, Test, TestCase } from "alsatian";
import { SomeModule } from "../src/some-module";    

export SomeModuleTests {

    @Test()
    public statusShouldBeTrueByDefault() {
        let instance = new SomeModule();
        
        Expect(instance.status).toBe(true);
    }
    
    @Test("Name should be null by default")
    public nameShouldBeNullByDefault() {
        let instance = new SomeModule();
        
        Expect(instance.name).toBe(null);
    }
    
    @TestCase("first name")
    @TestCase("apples")
    public shouldSetNameCorrectly(name: string) {
        let instance = new SomeModule();
        
        instance.setName(name);
        
        Expect(instance.name).toBe(name);
    }
    
}

For a full documentation, see alsatian’s GitHub repo.

chai-immutable plugin

Install from npm chai, chai-immutable, and ts-node

npm install --save-dev chai chai-immutable ts-node

Install types for mocha and chai

npm install --save-dev @types/mocha @types/chai

Write simple test file:

  import {List, Set} from 'immutable';
  import * as chai from 'chai';
  import * as chaiImmutable from 'chai-immutable';

  chai.use(chaiImmutable);

  describe('chai immutable example', () => {
    it('example', () => {
      expect(Set.of(1,2,3)).to.not.be.empty;

      expect(Set.of(1,2,3)).to.include(2);
      expect(Set.of(1,2,3)).to.include(5);
    })
  })

Run it in the console:

mocha --compilers ts:ts-node/register,tsx:ts-node/register 'test/**/*.spec.@(ts|tsx)'

tape

tape is minimalistic JavaScript testing framework, it outputs TAP-compliant markup.

To install tape using npm run command

npm install --save-dev tape @types/tape

To use tape with Typescript you need to install ts-node as global package, to do this run command

npm install -g ts-node

Now you are ready to write your first test

//math.test.ts
import * as test from "tape";

test("Math test", (t) => {
    t.equal(4, 2 + 2);
    t.true(5 > 2 + 2);

    t.end();
});

To execute test run command

ts-node node_modules/tape/bin/tape math.test.ts

In output you should see

TAP version 13
# Math test
ok 1 should be equal
ok 2 should be truthy

1..2
# tests 2
# pass  2

# ok

Good job, you just ran your TypeScript test.

Run multiple test files

You can run multiple test files at once using path wildcards. To execute all Typescript tests in tests directory run command

ts-node node_modules/tape/bin/tape tests/**/*.ts

jest (ts-jest)

jest is painless JavaScript testing framework by Facebook, with ts-jest can be used to test TypeScript code.

To install jest using npm run command

npm install --save-dev jest @types/jest ts-jest typescript

For ease of use install jest as global package

npm install -g jest

To make jest work with TypeScript you need to add configuration to package.json

//package.json
{
...
"jest": {
    "transform": {
      ".(ts|tsx)": "<rootDir>/node_modules/ts-jest/preprocessor.js"
    },
    "testRegex": "(/__tests__/.*|\\.(test|spec))\\.(ts|tsx|js)$",
    "moduleFileExtensions": ["ts", "tsx", "js"]
  }
}

Now jest is ready. Assume we have sample fizz buz to test

//fizzBuzz.ts
export function fizzBuzz(n: number): string {
    let output = "";
    for (let i = 1; i <= n; i++) {
        if (i % 5 && i % 3) {
            output += i + ' ';
        }
        if (i % 3 === 0) {
            output += 'Fizz ';
        }
        if (i % 5 === 0) {
            output += 'Buzz ';
        }
    }
    return output;
}

Example test could look like

//FizzBuzz.test.ts
/// <reference types="jest" />

import {fizzBuzz} from "./fizzBuzz";
test("FizzBuzz test", () =>{
    expect(fizzBuzz(2)).toBe("1 2 ");
    expect(fizzBuzz(3)).toBe("1 2 Fizz ");
});

To execute test run

jest

In output you should see

 PASS  ./fizzBuzz.test.ts
  ✓ FizzBuzz test (3ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        1.46s, estimated 2s
Ran all test suites.

Code coverage

jest supports generation of code coverage reports.

To use code coverage with TypeScript you need to add another configuration line to package.json.

{
...
  "jest": {
  ...
    "testResultsProcessor": "<rootDir>/node_modules/ts-jest/coverageprocessor.js"
  }
}

To run tests with generation of coverage report run

jest --coverage

If used with our sample fizz buzz you should see

 PASS  ./fizzBuzz.test.ts
  ✓ FizzBuzz test (3ms)

-------------|----------|----------|----------|----------|----------------|
File         |  % Stmts | % Branch |  % Funcs |  % Lines |Uncovered Lines |
-------------|----------|----------|----------|----------|----------------|
All files    |    92.31 |     87.5 |      100 |    91.67 |                |
 fizzBuzz.ts |    92.31 |     87.5 |      100 |    91.67 |             13 |
-------------|----------|----------|----------|----------|----------------|
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        1.857s
Ran all test suites.

jest also created folder coverage which contains coverage report in various formats, including user friendly html report in coverage/lcov-report/index.html