Modern SwiftUI: Dependencies & Testing, Part 2

Episode #220 • Jan 16, 2023 • Subscriber-Only

We conclude the series by taking control of the last two dependencies: persistence and speech recognition. We’ll make use of even more features of our new Dependencies library and we’ll write tests for our features that would have been impossible before.

Dependencies & Testing, Part 2
Introduction
00:05
Data manager dependency
00:35
Speech client dependency
25:30
Conclusion
39:11

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Introduction

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.

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

  1. 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.

  2. Use @Dependency(\.date) and @Dependency(\.uuid) to take control of all instances of
    Date() and UUID() in the application.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

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

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XCTest Dynamic Overlay

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XCTest Dynamic Overlay is a library we wrote that lets you write test helpers directly in your application and library code.

Packages authored by Point-Free

Swift Package Index

These packages are available as a package collection, usable in Xcode 13 or the Swift Package Manager 5.5.

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