This is basically an integration test for reducers. We are testing multiple layers of features, understanding how they interact with each other, and making assertions that they play nicely together. This is pretty huge! Again this is only a toy app, but in a large application you would be able to test that lots of tiny, reusable components continue working properly when they are plugged together. This is already powerful, and we haven’t even discussed effects yet.
Previous episode
Testable State Management: Effects
Introduction
Testing effects
Recap: the environment
Controlling the favorite primes save effect
Controlling the favorite primes load effect
Testing the favorite primes save effect
Testing the favorite primes load effect
Controlling the counter effect
Testing the counter effects
Next time: test ergonomics
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References
Dependency Injection Made Easy
Brandon Williams & Stephen Celis • May 21, 2018We first introduced the
Environmentconcept for controlling dependencies in this episode.Note Today we’re going to control the world! Well, dependencies to the outside world, at least. We’ll define the “dependency injection” problem and show a lightweight solution that can be implemented in your code base with little work and no third party library.
Dependency Injection Made Comfortable
Brandon Williams & Stephen Celis • Jun 4, 2018Our second episode on the
Environmentintroduces some patterns around building test data and builds intuitions around identifying the side effects that sneak into our applications.Note Let’s have some fun with the “environment” form of dependency injection we previously explored. We’re going to extract out a few more dependencies, strengthen our mocks, and use our Overture library to make manipulating the environment friendlier.
How to Control the World
Stephen Celis • Sep 24, 2018Stephen gave a talk on our
Environment-based approach to dependency injection at NSSpain 2018. He starts with the basics and slowly builds up to controlling more and more complex dependencies.Structure and Interpretation of Swift Programs
Colin Barrett • Dec 15, 2015Colin Barrett discussed the problems of dependency injection, the upsides of singletons, and introduced the
Environmentconstruct at Functional Swift 2015. This was the talk that first inspired us to test this construct at Kickstarter and refine it over the years and many other code bases.Elm: A delightful language for reliable webapps
Elm is both a pure functional language and framework for creating web applications in a declarative fashion. It was instrumental in pushing functional programming ideas into the mainstream, and demonstrating how an application could be represented by a simple pure function from state and actions to state.
Redux: A predictable state container for JavaScript apps.
The idea of modeling an application’s architecture on simple reducer functions was popularized by Redux, a state management library for React, which in turn took a lot of inspiration from Elm.
Composable Reducers
Brandon Williams • Oct 10, 2017A talk that Brandon gave at the 2017 Functional Swift conference in Berlin. The talk contains a brief account of many of the ideas covered in our series of episodes on “Composable State Management”.
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