---
uid: input-system-write-tests
---

# Write tests

When writing a test, use [`InputSystem.AddDevice<T>()`](xref:UnityEngine.InputSystem.InputSystem) to add new Devices.

```CSharp
    [Test]
    public void PlayerInput_CanInstantiatePlayer_WithSpecificControlScheme()
    {
        InputSystem.AddDevice<Gamepad>();
        var keyboard = InputSystem.AddDevice<Keyboard>();
        var mouse = InputSystem.AddDevice<Mouse>();

        var prefab = new GameObject();
        prefab.SetActive(false);
        var prefabPlayerInput = prefab.AddComponent<PlayerInput>();
        prefabPlayerInput.actions = InputActionAsset.FromJson(kActions);

        var player = PlayerInput.Instantiate(prefab, controlScheme: "Keyboard&Mouse");

        Assert.That(player.devices, Is.EquivalentTo(new InputDevice[] { keyboard, mouse }));
        Assert.That(player.controlScheme, Is.EqualTo("Keyboard&Mouse"));
    }
```

To feed input, the easiest way is to use the [`Press(button)`](xref:UnityEngine.InputSystem.InputTestFixture), [`Release(button)`](xref:UnityEngine.InputSystem.InputTestFixture), [`PressAndRelease(button)`](xref:UnityEngine.InputSystem.InputTestFixture), `Set(control,value)`, and [`Trigger(action)`](xref:UnityEngine.InputSystem.InputTestFixture) helper methods provided by [`InputTestFixture`](xref:UnityEngine.InputSystem.InputTestFixture).

```CSharp
    [Test]
    public void Actions_WhenDisabled_CancelAllStartedInteractions()
    {
        var gamepad = InputSystem.AddDevice<Gamepad>();

        var action1 = new InputAction("action1", binding: "<Gamepad>/buttonSouth", interactions: "Hold");
        var action2 = new InputAction("action2", binding: "<Gamepad>/leftStick");

        action1.Enable();
        action2.Enable();

        Press(gamepad.buttonSouth);
        Set(gamepad.leftStick, new Vector2(0.123f, 0.234f));

        using (var trace = new InputActionTrace())
        {
            trace.SubscribeTo(action1);
            trace.SubscribeTo(action2);

            runtime.currentTime = 0.234f;
            runtime.advanceTimeEachDynamicUpdate = 0;

            action1.Disable();
            action2.Disable();

            var actions = trace.ToArray();

            Assert.That(actions.Length, Is.EqualTo(2));
            //...
        }
    }
```

Alternatively, you can use code to feed arbitrary input events into the system, and run arbitrary input updates:

```CSharp
    [Test]
    public void PlayerInput_JoiningPlayerThroughButtonPress_WillFailIfDeviceIsNotUsableWithPlayerActions()
    {
        var playerPrefab = new GameObject();
        playerPrefab.SetActive(false);
        playerPrefab.AddComponent<PlayerInput>();
        playerPrefab.GetComponent<PlayerInput>().actions = InputActionAsset.FromJson(kActions);

        var manager = new GameObject();
        var listener = manager.AddComponent<MessageListener>();
        var managerComponent = manager.AddComponent<PlayerInputManager>();
        managerComponent.joinBehavior = PlayerJoinBehavior.JoinPlayersWhenButtonIsPressed;
        managerComponent.playerPrefab = playerPrefab;

        // Create a Device based on the HID layout with a single button control.
        const string kLayout = @"
            {
                ""name"" : ""TestDevice"",
                ""extend"" : ""HID"",
                ""controls"" : [
                    { ""name"" : ""button"", ""layout"" : ""Button"" }
                ]
            }
        ";

        InputSystem.RegisterLayout(kLayout);
        var device = InputSystem.AddDevice("TestDevice");

        using (StateEvent.From(device, out var eventPtr))
        {
            ((ButtonControl)device["button"]).WriteValueIntoEvent(1f, eventPtr);
            InputSystem.QueueEvent(eventPtr);
            InputSystem.Update();
        }

        Assert.That(listener.messages, Is.Empty);
        Assert.That(PlayerInput.all, Is.Empty);
    }
```

> [!NOTE]
> For reference, you can find the tests for the Input System itself in its [GitHub repository](https://github.com/Unity-Technologies/InputSystem/tree/stable/Assets/Tests/InputSystem).