DeallocTests 4.0 (1/5): groundwork – cleanup, CI, Dependency Injection as a package trait

[DanielCech]

Part 1 of 5. DeallocTests 4.0 series (merge in order): #25 groundwork → #26 expectDeallocation → #27 tracking, hints, DI → #28 configuration → #29 remove legacy, docs. Why 4.0, the breaking changes and the alternatives we looked at: see #25.

DeallocTests 4.0 in 5 PRs

DeallocTests checks that objects (screens, view models, coordinators, services) go away after use, so retain cycles fail a unit test instead of shipping. The idea is unchanged and still good. The implementation from 2019 is not: some checks give wrong answers, it can't be used from Swift Testing, and its failures don't say where the leak is. 4.0 keeps the idea and replaces the implementation.

This is a series of 5 stacked PRs from master to 4.0.0, one per theme. Each one builds, passes its tests (macOS with and without the Dependency Injection trait, and the iOS Simulator for the UI parts) and can be reviewed in one sitting. The last one ends at the reference branch dc/feat/v4-grace-period (ca911ab) plus the fixes from reviewing this series.

Why change it

3.0.1 has bugs that affect projects using it today:

• On macOS a test never finishes and waits out its whole timeout.
• If objectCreation returns nil (easy with [weak self]), the test crashes; a non-DeallocTestable object hangs it.
• Leaks are matched by class: if one FooViewController is freed and another leaks, the test passes.
• Only the root object is watched; its view model, store or child coordinator can leak unnoticed.
• The Dependency Injection dependency uses an SSH URL, so the package doesn't resolve on machines (and CI runners) without SSH access to GitHub.
• DeallocTestsDIFree is a symlinked copy of the target that switches DI on with canImport, which depends on whatever else is in the build.

And it doesn't fit how we write tests now:

• XCTest only; new projects use Swift Testing.
• Every tested class needs extension X: @retroactive DeallocTestable {}; every test subclasses DeallocTester and waits for an expectation.
• Failures point at a line inside the library, not at the test.
• Fixed sleeps make tests slow and still flaky on a loaded CI.
• The library has no tests of its own and no working CI.

What 4.0 looks like

// 3.x
extension ProfileViewController: @retroactive DeallocTestable {}

final class ProfileDeallocTester: DeallocTester {
    @MainActor
    func test_profile() async {
        let expectation = expectation(description: "dealloc test")
        await performDeallocTest(
            deallocTests: [DeallocTest(objectCreation: { _ in coordinator.makeProfileViewController() })],
            expectation: expectation
        )
        await fulfillment(of: [expectation], timeout: 60)
    }
}

// 4.0, Swift Testing or XCTest
await expectDeallocation(.present) { coordinator.makeProfileViewController() }

A leak fails on that line and says where to look:

LeakTests.swift:12: MyApp.ProfileViewController was not deallocated within 2 sec. It was watched for another 3 sec after that. Possible causes:
  • `onUpdate` is a closure. Make sure it captures self weakly
  • Or something outside still holds it: a parent's list of children, a cache or a singleton

• Any class, no conformances: the check holds a weak reference. The app target still needs no code at all.
• Real lifecycles: .loadView, .present, .push, .hosting (SwiftUI), .custom. Many leaks only appear on screen.
• Owned objects: trackForDeallocation checks a screen's view model together with the screen, and the system under test of any unit test.
• Dependency Injection: expectDeallocation(of: APIManaging.self, resolvedFrom: container).
• Configuration per test, suite or XCTest class: timeout, leaks as warnings while adopting, and a grace period that tells "released late" from "leaked".

Why the breaking changes

4.0 is a major version, and it uses that:

• DeallocTester, DeallocTestable and friends are removed, not deprecated. Everything they did is covered by expectDeallocation, and keeping them means two ways to write the same test plus a buggy code path to maintain.
• DeallocTestsDIFree is replaced by a package trait. Projects with STRV Dependency Injection change nothing; others turn the trait off.
• Swift 6.1 (Xcode 16.3) is required, for package traits.
• DefaultInitializable is removed; it wasn't related to dealloc testing.

Migration is mechanical: each DeallocTest becomes one expectDeallocation call and the conformance file is deleted (mapping table in the README). Projects that can't migrate yet stay on 3.x, which keeps working.

Proof on a real app: the JustFlip branch dc/feat/dealloc-tests-v4 has about 130 dealloc tests on 4.0: repositories, services, managers, every store in its SwiftUI view, every coordinator flow and the screens it opens. They run in about 45 s and found a real bug: ten store types shared one state object between all their instances.

Alternatives we looked at

Option	Why not instead
The 5-line trackForMemoryLeaks idiom (XCTest teardown block)	Fine for a view model in XCTest. No lifecycles, no Swift Testing (no teardown blocks there), no hints. 4.0's trackForDeallocation is this idiom for both frameworks.
XCTAssertNoLeak, SpecLeaks, MemoryLeakTestKit	Same category, dormant or dead since 2018–2022, no Swift Testing or SwiftUI.
LifetimeTracker, MLeaksFinder, FBRetainCycleDetector	Detect leaks while the app runs. Useful in debug builds, but they complement unit tests rather than replace them.
Point-Free	No leak-testing library. Its swift-issue-reporting solves failure reporting, which 4.0 needs only a 60-line slice of.
Apple	Nothing for leaks in XCTest or Swift Testing; Instruments and the Memory Graph debugger diagnose a leak once a test finds it.

No maintained library does unit-test leak checks with screen lifecycles, Swift Testing and SwiftUI support.

The PRs

#	PR	What	Source / tests	Breaking
1	#25	Remove dead tooling, DI over https, CI, DependencyInjection package trait replaces DeallocTestsDIFree	+7 −42 / −17	Yes
2	#26	expectDeallocation with .custom, .loadView, .present, .push, .hosting; both test frameworks	+574 / +425	No
3	#27	trackForDeallocation and .checksDeallocation, leak hints, expectDeallocation(of:resolvedFrom:)	+398 / +327	No
4	#28	Timeout, warning severity, grace period; traits and XCTest configuration	+221 / +245	No
5	#29	Remove DeallocTester & co., migrate the sample apps, README, migration guide, CHANGELOG	−420 + docs	Yes

Each PR targets the previous one. 2–4 only add API next to the old one, so the library works at every step; 5 removes the old API once the new one is complete. Each PR description has a "How to review" order, so the larger ones (2 and 3) can be read file by file.

Not in scope

• A runtime leak watcher for debug builds of the app. The app target stays free of DeallocTests code.
• DocC documentation; a follow-up after 4.0.0.

---

This PR: groundwork

Groundwork: remove tooling that no longer runs, make the package resolvable everywhere, get CI, and turn Dependency Injection into a package trait.

Why

• Dead tooling: Travis CI (Xcode 10.2), Danger, a Carthage bootstrap script, jazzy, .swift-version 5.0, .ruby-version, Objective-C umbrella headers and an empty source file. None of it runs.
• No tests: Tests/DeallocTestsSpec.swift imports Quick and Nimble, which the package doesn't declare, so the test target never compiled.
• SSH dependency URL: git@github.com:strvcom/ios-dependency-injection.git. SwiftPM resolves every dependency, so consumers without SSH access to GitHub, including many CI runners and DeallocTestsDIFree users, couldn't resolve the package.
• Fragile DIFree target: DeallocTestsDIFree compiled the same sources through a symlinked target and switched DI on with #if canImport(DependencyInjection), which depends on what else is in the build graph. Swift 6.1 package traits (SE-0450) do this properly.

What changes

• Dead files deleted; the broken test target removed (part 2 brings real tests).
• Package.swift: tools 6.1, https URL, a DependencyInjection trait on by default, STRV Dependency Injection 1.0.4 up to 2.x accepted (DeallocTests only uses API both have).
• DeallocTester checks #if DependencyInjection instead of canImport (7 one-word changes).
• Sample apps reference the package locally. The DIFree sample links DeallocTests with the trait off, and gets the @MainActor/await it needed to compile under Swift 6.
• CI builds the package with and without the trait, and for the iOS Simulator.

How to review

1. Package.swift and .github/workflows/ci.yml
2. DeallocTester.swift: canImport(DependencyInjection) → DependencyInjection
3. Sample apps: project.pbxproj switches only the package reference and product
4. The rest is deletions

Breaking change

• DeallocTestsDIFree is removed. Link DeallocTests, import DeallocTests, and disable the default traits:

  .package(url: "https://github.com/strvcom/DeallocTests.git", from: "4.0.0", traits: [])

  In an Xcode project, disable the package's default traits (Xcode 26.4+).
• Swift 6.1 / Xcode 16.3 is required.
• Projects using STRV Dependency Injection change nothing.

Testing

The package builds on macOS with and without the trait, and for the iOS Simulator. Both sample apps build for testing.

🤖 Generated with Claude Code

[Copilot]

Copilot review overview

🟢 Approval recommended

The package, sample, conditional-compilation, cleanup, and CI changes are internally consistent with the stated groundwork scope.

Review effort: Balanced
Findings: None

What changed in this PR

Modernizes package infrastructure by replacing the DIFree target with a package trait, adding CI, and removing obsolete tooling.

Changes:

• Adds conditional Dependency Injection support through a default package trait.
• Updates sample apps to use local package references.
• Replaces legacy tooling with GitHub Actions builds.

File	Description
.github/​workflows/​ci.yml	Adds macOS trait-matrix and iOS builds.
.jazzy.yml	Removes obsolete Jazzy configuration.
.ruby-version	Removes obsolete Ruby pin.
.swift-version	Removes obsolete Swift pin.
.travis.yml	Removes legacy Travis CI.
Dangerfile	Removes unused Danger checks.
Package.resolved	Uses HTTPS and updates the DI pin.
Package.swift	Adds the DI trait and removes DIFree.
SampleApps/​DeallocTestsAppDIFreeSPM/​DeallocTestsAppSPM.xcodeproj/​project.pbxproj	Migrates DIFree sample to the trait-disabled product.
SampleApps/​DeallocTestsAppDIFreeSPM/​DeallocTestsAppSPM.xcodeproj/​project.xcworkspace/​xcshareddata/​swiftpm/​Package.resolved	Removes obsolete sample dependency pins.
SampleApps/​DeallocTestsAppDIFreeSPM/​DeallocTestsAppSPMTests/​DeallocTestConformances.swift	Updates the module import.
SampleApps/​DeallocTestsAppDIFreeSPM/​DeallocTestsAppSPMTests/​MainCoordinatorDeallocTester.swift	Updates imports and actor isolation.
SampleApps/​DeallocTestsAppSPM/​DeallocTestsAppSPM.xcodeproj/​project.pbxproj	Adds a local package reference.
Sources/​DeallocTests.h	Removes an obsolete umbrella header.
Sources/​DeallocTests/​DeallocTests.h	Removes an obsolete umbrella header.
Sources/​DeallocTests/​DeallocTests.swift	Removes an empty placeholder source.
Sources/​DeallocTests/​DeallocTester.swift	Uses the package trait for conditional DI support.
Tests/​DeallocTestsSpec.swift	Removes the non-compiling empty test.
scripts/​bootstrap	Removes the obsolete Carthage bootstrap.

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