Episode #220: Modern SwiftUI: Dependencies & Testing, Part 2

We can make all of this much better if we finally take control over our dependency on the file system. In particular, the saving and loading of data to the file system.

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Our Dependencies library does not come with such a client immediately available to us, but it is quite easy to create. This will give us a chance to show off how one registers a new dependency with the library so that it is immediately available everywhere via the @Dependency property wrapper.

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Exercises

Use @Dependency(\.speechClient.authorizationStatus) in the standup detail view to show
alert when authorization has been denied.

Further, add an alert button action that uses @Dependency(\.openURL) to go to the
application notification settings.
Use @Dependency(\.date) and @Dependency(\.uuid) to take control of all instances of
Date() and UUID() in the application.
Write a test for the record screen that confirms that the timer pauses when the end meeting
alert is presented. Use a test clock to show that when the alert is up, the elapsedSeconds
state does not change when the clock is advanced. Dismiss the alert, advance the clock, and
assert that the timer continues.
Write a test for the deletion flow of a standup. Start the test off in a state with at least
one standup, and simulate drilling down to the detail, tapping the delete button, assert
that an alert was shown, simulate tapping the confirm deletion button, and then assert that
the screen popped back to the root and the standup was removed from the collection.
Let’s beef up the static DataManager.mock method to support accessing data from more than
one URL in a test. Instead of wrapping a mutable blob of Data, wrap a [URL: Data]
dictionary instead.
Let’s further beef up the DataManager dependency. Define a static testValue that calls
XCTFail by default. Then, define override methods that bypasses failure on a per-URL
basis.

References

Getting started with Scrumdinger

Apple

Learn the essentials of iOS app development by building a fully functional app using SwiftUI.

https://developer.apple.com/tutorials/app-dev-training/getting-started-with-scrumdinger

Standups App

Brandon Williams & Stephen Celis

A rebuild of Apple’s “Scrumdinger” application that demosntrates how to build a complex, real world application that deals with many forms of navigation (e.g., sheets, drill-downs, alerts), many side effects (timers, speech recognizer, data persistence), and do so in a way that is testable and modular.

https://github.com/pointfreeco/standups

CasePaths

Brandon Williams & Stephen Celis • Monday Aug 23, 2021

Custom Dump is one of our open source projects. It provides a collection of tools for debugging, diffing, and testing your application’s data structures.

https://github.com/pointfreeco/swift-custom-dump

SwiftUI Navigation

Brandon Williams & Stephen Celis • Tuesday Sep 7, 2021

A library we open sourced. Tools for making SwiftUI navigation simpler, more ergonomic and more precise.

https://github.com/pointfreeco/swiftui-navigation

combine-schedulers

Brandon Williams & Stephen Celis • Sunday Jun 14, 2020

An open source library that provides schedulers for making Combine more testable and more versatile.

http://github.com/pointfreeco/combine-schedulers

CasePaths

Brandon Williams & Stephen Celis

CasePaths is one of our open source projects for bringing the power and ergonomics of key paths to enums.

https://github.com/pointfreeco/swift-case-paths

Clocks

Brandon Williams & Stephen Celis • Wednesday Jun 29, 2022

An open source library of ours. A few clocks that make working with Swift concurrency more testable and more versatile.

https://github.com/pointfreeco/swift-clocks

Dependencies

Brandon Williams & Stephen Celis • Sunday Jan 9, 2022

An open source library of ours. A dependency management library inspired by SwiftUI’s “environment.”

https://github.com/pointfreeco/swift-dependencies

Identified Collections

Brandon Williams & Stephen Celis • Sunday Jul 11, 2021

Identified Collections is our open source library that provides an ergonomic, performant way to manage collections of identifiable data, and fits in perfectly with SwiftUI.

https://github.com/pointfreeco/swift-identified-collections