Holly Borla:
Swift 6.1 enables custom Swift Testing traits to perform logic before or after tests run in order to share set-up or tear-down logic. If you write a custom trait type which conforms to the new TestScoping protocol, you can implement a method to customize the scope in which each test or suite the trait is applied to will execute. For example, you could implement a trait which binds a task local value to a mocked resource:
struct MockAPICredentialsTrait: TestTrait, TestScoping {
func provideScope(for test: Test, testCase: Test.Case?, performing function: @Sendable () async throws -> Void) async throws {
let mockCredentials = APICredentials(apiKey: "fake")
try await APICredentials.$current.withValue(mockCredentials) {
try await function()
}
}
}
extension Trait where Self == MockAPICredentialsTrait {
static var mockAPICredentials: Self { Self() }
}
@Test(.mockAPICredentials)
func example() {
// Validate API usage, referencing `APICredentials.current`...
}
Because task locals cannot be separated into set-up and tear-down portions, they were previously only usable in Swift Testing if you repeated them within each test function. TestScoping gets rid of the indentation that entails and can also be applied at the suite level, so you don’t have to repeat it for each test. It’s great to have this functionality, though I think the implementation via traits feels a bit convoluted compared with XCTest’s invokeTest().
ST-0007:
Some test authors have expressed interest in allowing custom traits to access
the instance of a suite type for @Test instance methods, so the trait could
inspect or mutate the instance. Currently, only instance-level members of a
suite type (including init, deinit, and the test function itself) can access
self, so this would grant traits applied to an instance test method access to
the instance as well. This is certainly interesting, but poses several technical
challenges that puts it out of scope of this proposal.
It seems like a major limitation that any code factored out in this way can’t access properties or helper functions in the type that contains the test.
Some reviewers of this proposal pointed out that the hypothetical usage example shown earlier involving setting a task local value while a test is executing will likely become a common use of these APIs. To streamline that pattern, it would be very natural to add a built-in trait type which facilitates this. I have prototyped this idea and plan to add it once this new trait functionality lands.
Previously:
Update (2025-04-02): Christian Tietze:
I really like how Swift Testing Traits turns into how Emacs Lisp implements function advising.
You basically decorate a function call with a macro.
Unlike (Emacs) Lisp, you can't fiddle with the context of the called function and pass data along.
Programming Swift Concurrency Swift Programming Language Testing
Apple (security, downloads):
Clang now defines TARGET_OS_* conditionals as built-in macros based on the provided target triple.
[…]
Searching in the documentation viewer may start an indexing process which makes no progress. This may result in missing search results and increased CPU usage.
[…]
Fixed: Foundation encoders/decoders user info dictionaries now require Sendable values. This may cause build errors even in the Swift 5 language mode in small edge cases where the userInfo property is set to a value like init(myCustomInitializer:) where the initializer is defined in an extension on Dictionary with a Value == Any constraint.
[…]
Instruments 16.3 includes a new Processor Trace Instrument which uses hardware-supported, low-overhead CPU execution tracing to accurately reconstruct execution of the program.
[…]
In Xcode when you are in a test context you are now able to query for your test plan name and scheme name in the environment with the keys XCODE_TEST_PLAN_NAME and XCODE_SCHEME_NAME.
[…]
xcodebuild supports constraining the tests run through tests actions by tags. Use -only-testing-tags to include tests identified by a tags and -skip-testing-tags to omit tests identified by tags.
There are also lots of C++ and Swift/C++ improvements. It does not look like the issues with linking to certain frameworks on older versions of macOS (FB14667312) or calling async functions bridged from Objective-C (134442168) have been fixed yet.
Xcode Releases:
It is identical to RC2 that came out a couple of days ago.
Matt Massicotte (via Christian Tietze):
No, dynamic isolation is not bad.
But, I think we can also agree that static isolation is preferable. If you find yourself using dynamic isolation solely because it is a familiar pattern, that’s something to think about more deeply. Static isolation is a safer, clearer way to express what you need. That doesn’t mean you can always or even should start with it. Adopting concurrency will be a long process. Dynamic isolation is a very handy tool for getting there, I just don’t think it should typically be an end-state.
Rob Napier:
I’m wondering if there are changes to how DynamicActorIsolation works in Xcode 16.3. I’m seeing crashes due to running on a background thread that I don’t have with 16.2. The closure in question isn’t intended to be MainActor even though it’s defined in a View. With DynamicActorIsolation turned on, it seems to be getting MainActor assertions added, even if I mark it Sendable.
Paul Hudson:
If you upgraded to Xcode 16.3, be warned: there appears to be a simulator bug that causes network access to fail regularly. It doesn’t affect devices, just the simulator. You can work around it by using URLSession(configuration: .ephemeral) rather than URLSession.shared.
Previously:
Update (2025-04-02): Sean Heber:
Xcode 16.3 is seemingly refusing to remember the width of the canvas panel where SwiftUI previews live between tab switches and it is driving me bonkers and I’ve only had this version of Xcode a few hours.
C++ Programming Language Instruments Mac macOS 15 Sequoia Programming Swift Concurrency Swift Programming Language Testing Xcode
SpamSieve 3.1.2 improves the filtering accuracy of my Mac e-mail spam filter, amongst other enhancements and fixes.
Some interesting issues were:
I made some more table view improvements enabled by the lazy Core Data collections mentioned in the previous release. Since it no longer loads the whole selection into RAM, it’s now possible to operate on any size of selection in the Log window. The collection also adjusts the fetch batch size and the relationship prefetching based on what type of work is being done. For example, if you’re just scrolling the window it fetches less data than before until you actually select something to view. If you’re copying to the clipboard or it’s exporting the log for a diagnostic report, it fetches more rows and more relationships to reduce the number of trips to the database.
SpamSieve’s launch agent detects when Mail or Outlook launches, and then it launches the main SpamSieve app in response so that it can start filtering. This has worked without issue until recently, but now it seems that sometimes, if the user has set an app like Mail or Outlook as a login item, it will get launched before background launch agents. The fix is for the launch agent to look at which apps are already running when it launches, rather than only observing subsequent launches and quits.
Apple Mail’s scripting interface can get confused if there are multiple accounts with the same name. What I learned this month is that an account that doesn’t even show up in Mail ‣ Settings ‣ Accounts, e.g. it’s only in System Settings ‣ Internet Accounts, can also cause conflicts.
In mapping characters to key codes, I’ve found that the common advice to build up a table is problematic because sometimes there’s more than one key that corresponds to a given character. For example, '0' could map to either kVK_ANSI_0 or kVK_ANSI_Keypad0. In some cases, maybe the app should be aware of this and handle both options. For now, I’m building up the table in reverse order so that the lower numbered key codes (e.g. not on the numeric keypad) have precedence.
I got a new Mac, but the Migration Assistant did not preserve the notarization credentials in the keychain. notarytool started failing, which was detectable from looking at the logged output, but at first I didn’t realize it because part of my build script didn’t use set -e and so it kept running after commands had that failed. The script now checks for errors, and I also made some tune-ups to my automated notarization checks (e.g. using the newer syspolicy_check).
Previously:
Core Data Mac macOS 15 Sequoia Migration Assistant Notarization Optimization Programming SpamSieve Swift Programming Language
Elon Musk (Hacker News):
@xAI
has acquired
@X
in an all-stock transaction. The combination values xAI at $80 billion and X at $33 billion ($45B less $12B debt).
Since its founding two years ago, xAI has rapidly become one of the leading AI labs in the world, building models and data centers at unprecedented speed and scale.
X is the digital town square where more than 600M active users go to find the real-time source of ground truth and, in the last two years, has been transformed into one of the most efficient companies in the world, positioning it to deliver scalable future growth.
xAI and X’s futures are intertwined. Today, we officially take the step to combine the data, models, compute, distribution and talent. This combination will unlock immense potential by blending xAI’s advanced AI capability and expertise with X’s massive reach.
CNBC:
Musk launched xAI less than two years ago with a stated goal to “understand the true nature of the universe.” The startup has been trying to compete directly with OpenAI, the richly valued AI startup that Musk co-founded in 2015 as a non-profit research lab. He later left OpenAI and has recently been involved in a public relations and legal spat with the company and CEO Sam Altman over the direction that it’s taken.
[…]
X and xAI have already been intertwined, with xAI’s Grok chatbot available to users of the social media app.
It’s not clear to me whether this is essentially just a clever refinancing or whether something material has changed. On paper, Twitter is now profitable, and the business was sold for more than the original acquisition price. But the investors haven’t actually made a profit yet. They just own untradeable shares in a different private company. xAI, which seemed to come out of nowhere, is propped up by even more capital that it raised on the back of the AI boom, probably at more favorable terms. The ownership is now different, and perhaps the corporate structure and control are, too.
Richard Speed:
Looking into the future requires speculation. More Grok is likely, although Musk had already been heavily promoting xAI’s chatbot on X. As such, the service would have been further integrated regardless of the acquisition.
The main beneficiaries of the acquisition are X investors, who have endured years of turbulence since Musk acquired the platform. Owning shares in a growing AI startup is far more appealing than shares in a declining – though still significant – social media platform.
According to Gartner, worldwide generative AI spending is set to hit $644 billion in 2025, up 76.4 percent from 2024.
Previously:
Acquisition Artificial Intelligence Business Elon Musk Twitter Web
