Communicating with Code

Tests That Don't Suck

I'm Chris


A Little About Me

  • I dig #CodingJoy
  • I believe #CodeIsForHumans
  • I make tools:
    • JS Refactor
    • Dject
    • Mochadoc
    • Signet
    • Stubcontractor
    • And more...


Four great musicians brought together in harmony


Many great tools brought together in harmony

Legacy Code ...

... is any code without tests.

— Michael Feathers

WidgeTest9000 is Legacy Code:

widgeTest9000 source code

Let's write a test!

The Setup:

Completed test setup - where we are going

As you build your test

Follow the errors, then fake it 'til you make it!

(Or stub it, or spy it, or mock it...)

The Meat of the Test

The Three-A Approach:

  • Arrange
  • Act
  • Assert

The Arrangement and Action:

Play Video

The Assertion:

Play Video

Why Do We Say We Test?

  • To verify correct behavior
  • To capture information about bugs
  • To meet code coverage
  • We were told to

Tests Get No Respect

Are There Better Reasons To Test?

  • Communication
  • Communication
  • Communication

We Exercised The Code, But...

  • Description text should declare intent
  • Named variables expose meaning better
  • Complicated objects can be extracted away
  • Domain knowledge can be built in

Tests That Communicate

  • Inform other developers of original intent
  • Exemplify API use
  • Deepen understanding of the business domain
  • Expose criteria for correct behavior

Writing Great Code Is Like Writing A Great Story

It Never Happens In A Single Pass

Where Do We Start?

Sometimes choosing the right place to start is the hardest thing you'll do all day

Here's What I'll Do

  1. Update description
  2. Extract variables
  3. Build factory for setup data

Why Go That Way?

  1. A good description provides a goal
  2. Extracting variables is fast and easy
  3. Data factories improve signal to noise
  4. But first...

Model Your Domain

Use types as a domain specific language for your expectations

Off-The-Shelf to Bespoke Domain Types

Play Video

A Well-Described Test

Choice Words Make All The Difference

Choosing a test name

  • What does it do?
  • Why does it do that?
  • How does it align with the domain?

Everything is in a Name

Play Video

Extract Variable

Part of This Healthy Refactoring

Let's Extract!

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Automate Your Refactorings

Hot Take: If your editor doesn't support automated refactorings, ditch it.

Don't @ me.

Factories For Fun and Profit

Declarative Test Data with DataMother

Moving Our Spec to DataMother

Play Video

Happy Extractions, Everywhere!

Isolating Code Under Test

The more logic you touch, the more complicated your tests become

Generating Test Doubles At the Seam

Play Video

Touch Integration

Humans make mistakes; automatically generate all of the test doubles you can

Fix That Broken Test!

Play Video

Capture Side Effects in a New Test

Play Video

Dodging Double Duty

When the tests are clear and clean, you can leave the documentation work to the machine!

Generate API Docs

Play Video

The Takeaway

  • Tests should do more than exercise code
  • All good tests should facilitate communication
  • Tests + documentation is doubling your effort
  • The right tools can ease testing turmoil

The Source Code:

The Tools

  • VS Code
  • JS Refactor

The Libraries

  • Approvals
  • Dject
  • Chai
  • Datamother
  • Eslint
  • Mocha
  • Mochadoc
  • Signet
  • Sinon
  • Stubcontractor

The Slides

Thank You!