public void CollisionSurfaceTangent_ReturnsComponent()
{
// arrange
// 45 degree angle (down and to right) impacts
// the XZ horizontal plane
Vector3 impactDirection = new Vector3(1, -1, 0).normalized;
Vector3 surfaceNormal = Vector3.up;
Vector3 expected = Vector3.right;
// act
Vector3 tangent = PMath.CollisionSurfaceTangent(impactDirection, surfaceNormal);
// assert
Assert.AreEqual(expected, tangent, TestHelper.ShowVariables(expected, tangent));
}