Fix frozen download progress after a retry

Xcodes.xcodeproj/project.pbxproj

@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		AF29174092FE4E0F921AB001 /* InstallationProgressViewTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = AF29174092FE4E0F921AB002 /* InstallationProgressViewTests.swift */; };
 		14d2f5a1273f6c350cad4406 /* NewVersionNotificationTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 884f01aed2f43048ab4d3323 /* NewVersionNotificationTests.swift */; };
 		1596C2913043765600178C86 /* FileOperations.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1596C2903043765600178C86 /* FileOperations.swift */; };
 		1596C2923043765600178C86 /* FileOperations.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1596C2903043765600178C86 /* FileOperations.swift */; };
@@ -188,6 +189,7 @@
 /* End PBXCopyFilesBuildPhase section */
 
 /* Begin PBXFileReference section */
+		AF29174092FE4E0F921AB002 /* InstallationProgressViewTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = InstallationProgressViewTests.swift; sourceTree = "<group>"; };
 		1596C2903043765600178C86 /* FileOperations.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FileOperations.swift; sourceTree = "<group>"; };
 		15F5B88F2CCF09B900705E2F /* CryptoKit.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = CryptoKit.framework; path = System/Library/Frameworks/CryptoKit.framework; sourceTree = SDKROOT; };
 		3328073E2CA5E2C80036F691 /* SignInSecurityKeyPinView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SignInSecurityKeyPinView.swift; sourceTree = "<group>"; };
@@ -598,6 +600,7 @@
 			isa = PBXGroup;
 			children = (
 				CA452BBD259FDDBF0072DFA4 /* Fixtures */,
+				AF29174092FE4E0F921AB002 /* InstallationProgressViewTests.swift */,
 				CAC281E1259FA44600B8AB0B /* Bundle+XcodesTests.swift */,
 				CAC281E6259FA45A00B8AB0B /* Environment+Mock.swift */,
 				CAD2E7B72449575100113D76 /* AppStateTests.swift */,
@@ -980,6 +983,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				CAC281E7259FA45A00B8AB0B /* Environment+Mock.swift in Sources */,
+				AF29174092FE4E0F921AB001 /* InstallationProgressViewTests.swift in Sources */,
 				CAC281E2259FA44600B8AB0B /* Bundle+XcodesTests.swift in Sources */,
 				CA2518EC25A7FF2B00F08414 /* AppStateUpdateTests.swift in Sources */,
 				14d2f5a1273f6c350cad4406 /* NewVersionNotificationTests.swift in Sources */,

Xcodes/Frontend/InfoPane/InstallationStepDetailView.swift

@@ -16,6 +16,7 @@ struct InstallationStepDetailView: View {
                         style: .bar,
                         showsAdditionalDescription: true
                     )
+                    .id(ObjectIdentifier(progress))
 
                 case .authenticating, .unarchiving, .moving, .trashingArchive, .checkingSecurity, .finishing:
                     ProgressView()

Xcodes/Frontend/InfoPane/RuntimeInstallationStepDetailView.swift

@@ -24,6 +24,7 @@ struct RuntimeInstallationStepDetailView: View {
                     style: .bar,
                     showsAdditionalDescription: true
                 )
+                .id(ObjectIdentifier(progress))
 
             case .installing, .trashingArchive:
                 ObservingProgressIndicator(

Xcodes/Frontend/XcodeList/InstallationStepRowView.swift

@@ -18,6 +18,7 @@ struct InstallationStepRowView: View {
                     controlSize: .small,
                     style: .spinning
                 )
+                .id(ObjectIdentifier(progress))
             case .authenticating, .unarchiving, .moving, .trashingArchive, .checkingSecurity, .finishing:
                 ProgressView()
                     .scaleEffect(0.5)

XcodesTests/InstallationProgressViewTests.swift

@@ -0,0 +1,58 @@
+import Cocoa
+import SwiftUI
+import XCTest
+
+@testable import Xcodes
+
+@MainActor
+final class InstallationProgressViewTests: XCTestCase {
+    func testXcodeDetailUsesReplacementDownloadProgress() {
+        assertUsesReplacementProgress { progress in
+            InstallationStepDetailView(installationStep: .downloading(progress: progress))
+        }
+    }
+
+    func testXcodeRowUsesReplacementDownloadProgress() {
+        assertUsesReplacementProgress { progress in
+            InstallationStepRowView(
+                installationStep: .downloading(progress: progress),
+                highlighted: false,
+                cancel: {}
+            )
+        }
+    }
+
+    func testRuntimeDetailUsesReplacementDownloadProgress() {
+        assertUsesReplacementProgress { progress in
+            RuntimeInstallationStepDetailView(installationStep: .downloading(progress: progress))
+        }
+    }
+
+    private func assertUsesReplacementProgress<Content: View>(
+        @ViewBuilder content: (Progress) -> Content,
+        file: StaticString = #filePath,
+        line: UInt = #line
+    ) {
+        let original = Progress(totalUnitCount: 100)
+        original.completedUnitCount = 6
+        let hostingView = NSHostingView(rootView: content(original))
+        hostingView.frame = NSRect(x: 0, y: 0, width: 420, height: 180)
+        hostingView.layoutSubtreeIfNeeded()
+        XCTAssertEqual(progressIndicator(in: hostingView)?.doubleValue, 0.06, file: file, line: line)
+
+        // A resumed download supplies a new Progress while remaining in the downloading stage.
+        let replacement = Progress(totalUnitCount: 100)
+        replacement.completedUnitCount = 75
+        hostingView.rootView = content(replacement)
+        hostingView.layoutSubtreeIfNeeded()
+
+        XCTAssertEqual(progressIndicator(in: hostingView)?.doubleValue, 0.75, file: file, line: line)
+    }
+
+    private func progressIndicator(in view: NSView) -> NSProgressIndicator? {
+        if let indicator = view as? NSProgressIndicator {
+            return indicator
+        }
+        return view.subviews.lazy.compactMap { self.progressIndicator(in: $0) }.first
+    }
+}