Test that reusing or cancelling an image view interrupts the request

Tests/RequestDLInternalsTests/Sources/Client/Client Manager/InternalsClientManagerTests.swift

@@ -287,12 +287,15 @@ struct InternalsClientManagerTests {
                 sessionConfiguration: overflowing
             )
 
-            // Then: served straight away, the ceiling overshot rather than enforced, and nothing
-            // in flight was torn down to get there.
+            // Then: served without waiting for a busy client, the ceiling overshot rather than
+            // enforced, and nothing in flight was torn down to get there. The bound is not a
+            // speed claim: a caller that waited for a client to free up would wait for the 60 s
+            // request that holds it, or for ever, and a loaded runner takes a second or more
+            // over a call that does nothing but bookkeeping.
             #if canImport(Darwin)
-            #expect(DispatchTime.now().uptimeNanoseconds - start < 1_000_000_000)
+            #expect(DispatchTime.now().uptimeNanoseconds - start < 30_000_000_000)
             #else
-            #expect(ContinuousClock.now - start < .seconds(1))
+            #expect(ContinuousClock.now - start < .seconds(30))
             #endif
             #expect(manager.count == maximumCount + 1)
             #expect(busy.allSatisfy { $0.isRunning })

Tests/RequestDLTests/Image/AppKit/NSImageViewRequestDLTests.swift

@@ -7,6 +7,7 @@ import SwiftAsyncStream
 import Testing
 
 @_spi(Private) @testable import RequestDL
+@testable import RequestDLTestSupport
 
 #if canImport(AppKit) && !targetEnvironment(macCatalyst)
 import AppKit
@@ -107,6 +108,75 @@ struct NSImageViewRequestDLTests {
         // Then
         #expect(await !completed.value)
     }
+
+    /// The completion not firing is not the same as the request being stopped: a cell that is
+    /// reused has to free the connection of the image it no longer shows.
+    @Test
+    func reusingTheImageViewInterruptsTheRequestOfThePreviousLoad() async throws {
+        // Given
+        let imageView = NSImageView()
+        let started = Flag()
+        let interrupted = Flag()
+
+        imageView.rdl.setImage(
+            id: "interrupted-by-reuse-\(UUID())",
+            task: StubImageTask {
+                await started.set()
+
+                do {
+                    try await Task.sleep(nanoseconds: 60_000_000_000)
+                } catch {
+                    await interrupted.set()
+                    throw error
+                }
+
+                return .init(head: .stub, payload: .onePixelPNG)
+            }
+        )
+
+        try await eventually { await started.value }
+
+        // When
+        imageView.rdl.setImage(
+            id: "replacement-\(UUID())",
+            task: StubImageTask { .init(head: .stub, payload: .onePixelPNG) }
+        )
+
+        // Then
+        try await eventually { await interrupted.value }
+    }
+
+    @Test
+    func cancelInterruptsTheRequestOfThePendingLoad() async throws {
+        // Given
+        let imageView = NSImageView()
+        let started = Flag()
+        let interrupted = Flag()
+
+        imageView.rdl.setImage(
+            id: "interrupted-by-cancel-\(UUID())",
+            task: StubImageTask {
+                await started.set()
+
+                do {
+                    try await Task.sleep(nanoseconds: 60_000_000_000)
+                } catch {
+                    await interrupted.set()
+                    throw error
+                }
+
+                return .init(head: .stub, payload: .onePixelPNG)
+            }
+        )
+
+        try await eventually { await started.value }
+
+        // When
+        imageView.rdl.cancel()
+
+        // Then
+        try await eventually { await interrupted.value }
+    }
 }
 
 // MARK: - Test helpers

Tests/RequestDLTests/Image/UIKit/UIImageViewRequestDLTests.swift

@@ -7,6 +7,7 @@ import SwiftAsyncStream
 import Testing
 
 @_spi(Private) @testable import RequestDL
+@testable import RequestDLTestSupport
 
 #if canImport(UIKit) && !os(watchOS)
 import UIKit
@@ -107,6 +108,75 @@ struct UIImageViewRequestDLTests {
         // Then
         #expect(await !completed.value)
     }
+
+    /// The completion not firing is not the same as the request being stopped: a cell that is
+    /// reused has to free the connection of the image it no longer shows.
+    @Test
+    func reusingTheImageViewInterruptsTheRequestOfThePreviousLoad() async throws {
+        // Given
+        let imageView = UIImageView()
+        let started = Flag()
+        let interrupted = Flag()
+
+        imageView.rdl.setImage(
+            id: "interrupted-by-reuse-\(UUID())",
+            task: StubImageTask {
+                await started.set()
+
+                do {
+                    try await Task.sleep(nanoseconds: 60_000_000_000)
+                } catch {
+                    await interrupted.set()
+                    throw error
+                }
+
+                return .init(head: .stub, payload: .onePixelPNG)
+            }
+        )
+
+        try await eventually { await started.value }
+
+        // When
+        imageView.rdl.setImage(
+            id: "replacement-\(UUID())",
+            task: StubImageTask { .init(head: .stub, payload: .onePixelPNG) }
+        )
+
+        // Then
+        try await eventually { await interrupted.value }
+    }
+
+    @Test
+    func cancelInterruptsTheRequestOfThePendingLoad() async throws {
+        // Given
+        let imageView = UIImageView()
+        let started = Flag()
+        let interrupted = Flag()
+
+        imageView.rdl.setImage(
+            id: "interrupted-by-cancel-\(UUID())",
+            task: StubImageTask {
+                await started.set()
+
+                do {
+                    try await Task.sleep(nanoseconds: 60_000_000_000)
+                } catch {
+                    await interrupted.set()
+                    throw error
+                }
+
+                return .init(head: .stub, payload: .onePixelPNG)
+            }
+        )
+
+        try await eventually { await started.value }
+
+        // When
+        imageView.rdl.cancel()
+
+        // Then
+        try await eventually { await interrupted.value }
+    }
 }
 
 // MARK: - Test helpers