Writing Unit Tests with NSubstitute (Unity)

References

• About Unity Test Framework
• What Is NUnit
• Assert.Greater
• NSubstitute
• Managed plug-ins
• NSubstitute NuGet

Table of Content

• References
• Table of Content
• Install the Unity Test Framework
• Assembly Definitions
• Tests Files
• Add NSubstitute
• Tests Examples

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Install the Unity Test Framework

• Make sure the Test Framework package is installed in the project and updated.

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Assembly Definitions

• Create two Assembly Definitions, one for the Edit Mode tests and another for the Play Mode tests.
• Edit Mode tests only run in the Unity Editor and have access to the Editor code in addition to the game code.

• Make sure to add a reference to the Assembly Definition with the code for your game, so you can tests its classes.

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Tests Files

• Create test files using the template or write your own from scratch.

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Add NSubstitute

• You will need to obtain the .dll from the NuGet registry manually, and add it to the Unity project as a Managed Plug-in (Which is a .NET assembly).
• Go to the NuGet package for NSubstitue and download the .nupkg

• Change the extension to .zip to be able to extract its contents.

• Copy over the .dll corresponding to the Api Compatibility Level set in the Player Settings of your project. (Most likely .NET Standard 2.1)
• Repeat the process for any dependency of the library.

• Reference the Assembly in the Assembly Definition of your tests, to be able to use NSubstitute.

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Tests Examples

• [UnityTest] tests allow you to skip a frame in the simulation by doing yield return null, or skip many doing yield return new WaitForSeconds().
• [Test] tests don't run the simulation of the game, you can't skip frames.

1[UnityTest]
2public IEnumerator test__on_trigger_enter__invokes_gun_reclaim_bullet()
3{
4    var gun = Substitute.For<IGun>();
5
6    var bullet = CreateBullet();
7    bullet.gun = gun;
8    bullet.speed = 20.0f;
9
10    var limits = CreateProjectilesLimit();
11
12    yield return new WaitForSeconds(0.05f);
13
14    gun.Received().ReclaimBullet(bullet);
15
16    GameObject.Destroy(bullet.gameObject);
17    GameObject.Destroy(limits.gameObject);
18}
19
20public static Bullet CreateBullet()
21{
22    var obj = new GameObject("Bullet");
23    obj.layer = LAYER_PLAYER_PROJECTILES;
24
25    var rigidbody = obj.AddComponent<Rigidbody>();
26    rigidbody.useGravity = false;
27
28    var collider = obj.AddComponent<BoxCollider>();
29    collider.size = new Vector3(1.0f, 1.0f, 1.0f);
30    collider.isTrigger = true;
31
32    var bullet = obj.AddComponent<Bullet>();
33
34    return bullet;
35}
36
37private BoxCollider CreateProjectilesLimit()
38{
39    var obj = new GameObject("ProjectilesLimit");
40    obj.layer = Utils.LAYER_PROJECTILES_LIMITS;
41
42    obj.transform.position = new Vector3(0.0f, 0.0f, 1.1f);
43
44    var collider = obj.AddComponent<BoxCollider>();
45    collider.size = new Vector3(5.0f, 5.0f, 1.0f);
46    collider.isTrigger = true;
47
48    return collider;
49}