Unit tests are a vital tool for writing quality code. They also happen to be the best kind of documentation for your software, the kind that never gets out of date.
Test-Driven Development is an excellent way of writing code but many people push back against it. To convince your team to adopt it, lead by example. Don't preach. Let the quality of the code your wrote with TDD talk for itself and only suggest TDD when people ask about it.
Each XCTNSPredicateExpectation requires a timeout of at least 1.1 seconds. That's will unnecessarily slow down your test suite. You can use Nimble's toEventually instead and make your tests as fast as possible.
Swift @Published properties come with an associated Combine Publisher that emits values over time. This free XCTest tutorial explains when to write a unit test that accesses the property directly and when it's instead necessary to subscribe to it using the sink operator.
I published a YouTube video with a tutorial on implementing the FizzBuzz algorithm using Test-Driven Development. While recording, I made a couple of thinking or coding mistakes, and, sure enough, the tests immediately pointed them out.
To test SwiftUI applications, don't test SwiftUI code. The SwiftUI framework doesn't lend itself to writing unit tests so don't try to shoehorn views in your test harness. Instead, split layout declaration form content generation logic.
A roundup of the testing-related new features announced at WWDC 2021. Including Xcode Cloud, how to test code using async/await, the new XCTExpectFailure and addTearDownBlock APIs, and the new Test Repetition configuration in Test Plans.
Swift 5.5 and Xcode 13 introduce the async/await pattern for concurrent code. This tutorial post shows how to write unit tests for asynchronous code in Swift using the XCTest framework.
Testing Swift date comparison code with XCTest can result in indeterministic tests because of the passage of time. To make tests robust and deterministic, decouple them from the system clock by injecting the reference date.
When writing unit tests in Swift for complex objects, you may need to write a lot of setup boilerplate code in the arrange phase. Scenario Builders are a pattern that extracts and encapsulated all that logic in a single component with an English-like API. This tutorial shows how to build a Scenario Builder in Swift and looks at its pros and cons.
Snippets to test the behavior of Combine Publishers in XCTest ready to copy and paste into Xcode
The "You Don't Need It Yet" technique to ship software on a schedule results in fast real-world feeback. The same mindset can be applied with Test-Driven Development to move between the Red, Green, and Refactor stages faster.
The XCTest Swift testing framework has a limited offer of assertions. There's only so much you can do with XCTAssertTrue and XCTAssertEqual. This XCTest tutorial shows how to create custom assertions to make your unit tests and UI tests shorter and clearer.
Result is one of the most useful types in the Swift language. Learn how to write better unit tests using Result in this XCTest tutorial.
Scientist can learn a lot from failed experiments. To do so, they must be methodical and collect all sorts of information. Softwar developers can learn a lot from failures, too. What are the practicies that can make learning easier?
How to make the unit tests of your SwiftUI app safer and faster by preventing them from running the program startup flow. This will avoid all of the launch operations like network requests or reads from the local storage that would affect the global state.
When the output value of a function changes often but the logic to pick it doesn't, adding a separation layer will make unit tests easier to maintain.
A collection of ways to run a single test or a subset of tests using Xcode.
The answer to "How can I test that a view controller presents another view controller when something happens?" is as simple as defining a delegate.
When testing delegates, we are asserting rigid implementation details. Here's a way to make those tests more flexible.
But you should track it anyways.
An overview of the different kind of doubles we can use in our tests, and how to write them in Swift.
There is a subtle way to overload software components, by making them both take decision and act on them. We can simplify these bloated components by separating the responsibility of taking decisions from the one action on them. This will result in leaner and easier to maintain software, and is made simple by the Swift type system.
Some code ends up requiring a lot of duplication to be tested. You can remove it by using helper functions encapsulating the shared assertion logic.
Keeping tests short and focused is important for the health of the test suite. A fixture method to generate instances with default values in the tests helps keeping the setup code short, focused, and readable
Using protocols describing a single capability or action that can be performed is a way to enhance local reasoning and facilitate testability
A look at the benefits of writing unit tests before production code, in other words TDD.
A look at how beforeSuite and afterSuite behave in the Quick testing framework, and the dangers of using them
A look at how nested beforeEach and afterEach behave in the Quick testing framework.
The Nimble matchers framework provides two ways assert expectations on asynchronous code, this post explores when to use one or the other.
Testing async code is not simple, but XCTest provides us with all the required tool. This post shows how to wait for an expectation to be fulfilled based on a Swift closure.
In Swift it is possible to pass a reference to a type itself, not just to an instance of it. This post shows how to use this capability to test legacy code.
Third party code can be hard to test, but you can use Swift's protocols to abstract its details and improve testability
Good unit tests are fast and deterministic. Testing code that hits the network could undermine this goal, but using OHHTTPStubs we can take back control of our tests. This post explores the advantages of stubbing the network, and provide a guide on how to do it with OHHTTPStubs.
In this post we are going to look at why hitting the network from your unit tests is a bad thing, and introduce some way to solve the problem.
A look at how to write tests for async code when using the Quick and Nimble Swift frameworks. This post is part of the Practical Testing in Swift series.
In this second post of the Practical Testing in Swift we a look at strategies to test how objects call their delegate methods or set property on them.
How to prevent the unit test target from loading the AppDelegate and have faster tests execution.
Unit and acceptance test are powerful tools that can be used to identify and fix bugs. Let's see how using a bugged Swift app as an example.
I attended /dev/world/2015 in Melbourne this week. It has been a great conference, full of very friendly and smart people. Being a test and automation fanboy I attended as many talks related to that topic as I could. These are my notes.
A look at how to write classes and structs that expose their dependencies as initialization arguments in Swift.
Sometimes the idea we get when reading a class interface is different from what is actually going on inside its implementation, for example there could be several hidden dependencies. Making a class dependency explicit in its interface is a useful technique to make the code simpler to understand, and easier to test.
Realm is a mobile database that, unlike CoreData, is easy to test. In this post we will discuss some ideas on how to test an app using Realm as its database.
An interesting and powerful, yet not at all documented feature of Spetca are global beforeEach and afterEach hooks. In this post we'll see how to configure them, and how to blacklist classes from running them. Updated for version 0.5
Writing unit tests for our iOS and OS X projects not only is important, but should be always part of the development cycle. As such the way we write the tests is as important, and having the option to write tests that easily explain their purpose can drastically increase the quality of the suite. Specta and Expecta are two libraries that provide a different way to writing tests than XCTest, let's see what we can gain by using such approach.
Keyboard shortcuts are easies way to start increasing your productivity. Let's look at how to run tests in Xcode without ever touching the mouse.
In this post we'll look at the main tools and libraries available to write unit and acceptance tests for iOS and OS X applications, as well as the solutions to host Continuous Integration for our projects.
An interesting and powerful, yet not at all documented feature of Spetca are global beforeEach and afterEach hooks. In this post we'll see how to configure them, and how to blacklist classes from running them.
How to invoke xcodebuild to run the tests from the command line and how to format its output using xcbeautify or xcpretty