Add test coverage of corrupt realm creating backup

osu.Game.Tests/Collections/IO/ImportCollectionsTest.cs

@@ -138,7 +138,7 @@ public async Task TestSaveAndReload()
         {
             string firstRunName;
 
-            using (var host = new CleanRunHeadlessGameHost(bypassCleanup: true))
+            using (var host = new CleanRunHeadlessGameHost(bypassCleanupOnDispose: true))
             {
                 firstRunName = host.Name;
 

osu.Game.Tests/NonVisual/CustomDataDirectoryTest.cs

@@ -315,6 +315,26 @@ public void TestMigrationToSeeminglyNestedTarget()
             }
         }
 
+        [Test]
+        public void TestBackupCreatedOnCorruptRealm()
+        {
+            using (var host = new CustomTestHeadlessGameHost())
+            {
+                try
+                {
+                    File.WriteAllText(host.InitialStorage.GetFullPath(OsuGameBase.CLIENT_DATABASE_FILENAME, true), "i am definitely not a realm file");
+
+                    LoadOsuIntoHost(host);
+
+                    Assert.That(host.InitialStorage.GetFiles(string.Empty, "*_corrupt.realm"), Has.One.Items);
+                }
+                finally
+                {
+                    host.Exit();
+                }
+            }
+        }
+
         private static string getDefaultLocationFor(CustomTestHeadlessGameHost host)
         {
             string path = Path.Combine(TestRunHeadlessGameHost.TemporaryTestDirectory, host.Name);
@@ -347,7 +367,7 @@ public class CustomTestHeadlessGameHost : CleanRunHeadlessGameHost
             public Storage InitialStorage { get; }
 
             public CustomTestHeadlessGameHost([CallerMemberName] string callingMethodName = @"")
-                : base(callingMethodName: callingMethodName)
+                : base(callingMethodName: callingMethodName, bypassCleanupOnSetup: true)
             {
                 string defaultStorageLocation = getDefaultLocationFor(this);
 

osu.Game/Tests/CleanRunHeadlessGameHost.cs

@@ -15,30 +15,38 @@ namespace osu.Game.Tests
     /// </summary>
     public class CleanRunHeadlessGameHost : TestRunHeadlessGameHost
     {
+        private readonly bool bypassCleanupOnSetup;
+
         /// <summary>
         /// Create a new instance.
         /// </summary>
         /// <param name="bindIPC">Whether to bind IPC channels.</param>
         /// <param name="realtime">Whether the host should be forced to run in realtime, rather than accelerated test time.</param>
-        /// <param name="bypassCleanup">Whether to bypass directory cleanup on host disposal. Should be used only if a subsequent test relies on the files still existing.</param>
+        /// <param name="bypassCleanupOnSetup">Whether to bypass directory cleanup on <see cref="SetupForRun"/>.</param>
+        /// <param name="bypassCleanupOnDispose">Whether to bypass directory cleanup on host disposal. Should be used only if a subsequent test relies on the files still existing.</param>
         /// <param name="callingMethodName">The name of the calling method, used for test file isolation and clean-up.</param>
-        public CleanRunHeadlessGameHost(bool bindIPC = false, bool realtime = true, bool bypassCleanup = false, [CallerMemberName] string callingMethodName = @"")
+        public CleanRunHeadlessGameHost(bool bindIPC = false, bool realtime = true, bool bypassCleanupOnSetup = false, bool bypassCleanupOnDispose = false,
+                                        [CallerMemberName] string callingMethodName = @"")
             : base($"{callingMethodName}-{Guid.NewGuid()}", new HostOptions
             {
                 BindIPC = bindIPC,
-            }, bypassCleanup: bypassCleanup, realtime: realtime)
+            }, bypassCleanup: bypassCleanupOnDispose, realtime: realtime)
         {
+            this.bypassCleanupOnSetup = bypassCleanupOnSetup;
         }
 
         protected override void SetupForRun()
         {
-            try
+            if (!bypassCleanupOnSetup)
             {
-                Storage.DeleteDirectory(string.Empty);
-            }
-            catch
-            {
-                // May fail if a logging target has already been set via OsuStorage.ChangeTargetStorage.
+                try
+                {
+                    Storage.DeleteDirectory(string.Empty);
+                }
+                catch
+                {
+                    // May fail if a logging target has already been set via OsuStorage.ChangeTargetStorage.
+                }
             }
 
             // base call needs to be run *after* storage is emptied, as it updates the (static) logger's storage and may start writing