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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
import Testing
/// A base test case class for Swift Testing test suites that provides common testing utilities,
/// such as memory leak detection.
///
/// ## Usage
///
/// **IMPORTANT:** To ensure correct memory leak detection, `SwiftTestingHelper` must be declared
/// as the **first stored property** in your test struct and tracked objects are declared as a **local variable**.
/// This ensures that it deallocates last, after all tracked objects have been deallocated.
public final class SwiftTestingHelper {
private struct MemoryLeakCheck {
weak var object: AnyObject?
let location: SourceLocation
}
private var memoryLeakCheck: MemoryLeakCheck?
public init() {}
/// Tracks an object for memory leak detection.
///
/// Registers an object to be checked for memory leaks when the test completes. The object is
/// held with a weak reference, and during deinitialization, verifies the object was deallocated.
///
/// - Note: Only one object can be tracked per `SwiftTestingHelper` instance.
/// To track multiple objects, we will need to expand, but no use case for it currently so keeping it simple.
///
/// Example:
/// ```swift
/// @Suite
/// struct MyTests {
/// let helper = SwiftTestingHelper() // ✓ Declare FIRST
/// // Other properties here...
///
/// @Test
/// func testMyClass() {
/// let subject = helper.trackForMemoryLeaks(MyClass()) // ✓ Local variable
/// // test code
/// } // ← subject deallocates here, before helper
/// ```
@discardableResult
public final func trackForMemoryLeaks<T: AnyObject>(
_ instance: T,
fileID: String = #fileID,
filePath: String = #filePath,
line: Int = #line,
column: Int = #column
) -> T {
let location = SourceLocation(fileID: fileID, filePath: filePath, line: line, column: column)
memoryLeakCheck = MemoryLeakCheck(object: instance, location: location)
return instance
}
deinit {
guard let memoryLeakCheck else {
Issue.record("No objects to verify for memory leaks.")
return
}
#expect(memoryLeakCheck.object == nil, "Potential memory leak detected", sourceLocation: memoryLeakCheck.location)
}
}