ppy/osu · error · InvalidOperationException

Using the {nameof(OsuTestScene)} dummy API is not supported

Error message

Using the {nameof(OsuTestScene)} dummy API is not supported when {nameof(UseOnlineAPI)} is true

What it means

OsuTestScene.API is a convenience accessor for the in-process DummyAPIAccess. When a test scene overrides UseOnlineAPI => true, no DummyAPIAccess is created (the real OsuGameBase IAPIProvider is used instead), so reading the dummy-backed API property is invalid and throws.

Source

Thrown at osu.Game/Tests/Visual/OsuTestScene.cs:61

        [Cached]
        protected Bindable<WorkingBeatmap> Beatmap { get; } = new Bindable<WorkingBeatmap>();

        [Cached]
        protected Bindable<RulesetInfo> Ruleset { get; } = new Bindable<RulesetInfo>();

        [Cached]
        protected Bindable<IReadOnlyList<Mod>> SelectedMods { get; } = new Bindable<IReadOnlyList<Mod>>(Array.Empty<Mod>());

        protected new DependencyContainer Dependencies { get; private set; }

        protected IResourceStore<byte[]> Resources;

        protected IAPIProvider API
        {
            get
            {
                if (UseOnlineAPI)
                    throw new InvalidOperationException($"Using the {nameof(OsuTestScene)} dummy API is not supported when {nameof(UseOnlineAPI)} is true");

                return dummyAPI;
            }
        }

        private DummyAPIAccess dummyAPI;

        /// <summary>
        /// Whether this test scene requires real-world API access.
        /// If true, this will bypass the local <see cref="DummyAPIAccess"/> and use the <see cref="OsuGameBase"/> provided one.
        /// </summary>
        protected virtual bool UseOnlineAPI => false;

        /// <summary>
        /// A database context factory to be used by test runs. Can be isolated and reset by setting <see cref="UseFreshStoragePerRun"/> to <c>true</c>.
        /// </summary>
        /// <remarks>
        /// In interactive runs (ie. VisualTests) this will use the user's database if <see cref="UseFreshStoragePerRun"/> is not set to <c>true</c>.

View on GitHub (pinned to d9c73e12ad)

Solutions

Do not read OsuTestScene.API when UseOnlineAPI is true; resolve IAPIProvider from dependencies via [Resolved].
Keep UseOnlineAPI => false if the test genuinely needs the DummyAPIAccess.
Gate any dummy-specific access behind `if (!UseOnlineAPI)`.

Example fix

// before
protected override bool UseOnlineAPI => true;
var api = API; // throws

// after
protected override bool UseOnlineAPI => true;
[Resolved]
private IAPIProvider api { get; set; }

Defensive patterns

Strategy: validation

Validate before calling

IAPIProvider api = UseOnlineAPI
    ? Dependencies.Get<IAPIProvider>()   // real OsuGameBase API
    : API;                                // DummyAPIAccess
// use `api`, never read OsuTestScene.API when UseOnlineAPI is true

Prevention

When flipping UseOnlineAPI => true, audit every read of the inherited API property.
Prefer [Resolved] IAPIProvider over OsuTestScene.API in test scenes.
Gate dummy-API-specific helpers behind if (!UseOnlineAPI).

When it happens

Trigger: A test scene sets UseOnlineAPI => true and then reads the inherited `API` property (or otherwise relies on the dummy API).

Common situations: Opting a test into real online-API access while legacy code paths still read OsuTestScene.API; copying a dummy-API-based test and flipping UseOnlineAPI.

Related errors

AI-assisted analysis of ppy/osu@d9c73e12ad (2026-08-13). Data as JSON: /api/errors/a19d12e0c737f063. Report an issue: GitHub.