Unit tests - entity framework - unit-testing

Question

I use NUnitAdapter. I have unit test for my update method:
[Test]
public void UpdateBuisness()
{
var buis = new Buisness()
{
Name = "a",
Id = 4,
Enabled = true
};
_buisnessRepository.Insert(buis);
buis.Name = "b";
_buisnessRepository.Update(buis);
Assert.AreEqual(buis.Name, _buisnesses.Last().Name);
}
Update method:
public void Update(Buisness entity)
{
_context.Entry(entity).State = EntityState.Modified;
}
And I get error:
This is weird, because for my co-workers all works.
My mock:
var mockBuisnessesDbSet = new Mock<DbSet<Buisness>>();
mockBuisnessesDbSet.As<IQueryable<Buisness>>().Setup(m => m.Provider)
.Returns(new TestDbAsyncQueryProvider<Buisness>(_buisnesses.Provider));
mockBuisnessesDbSet.As<IQueryable<Buisness>>().Setup(m => m.Expression).Returns(_buisnesses.Expression);
mockBuisnessesDbSet.As<IQueryable<Buisness>>().Setup(m => m.ElementType).Returns(_buisnesses.ElementType);
mockBuisnessesDbSet.As<IDbAsyncEnumerable<Buisness>>()
.Setup(m => m.GetAsyncEnumerator())
.Returns(new TestDbAsyncEnumerator<Buisness>(_buisnesses.GetEnumerator()));
mockBuisnessesDbSet.As<IQueryable<Buisness>>().Setup(m => m.GetEnumerator()).Returns(_buisnesses.GetEnumerator());
mockBuisnessesDbSet.Setup(x => x.Add(It.IsAny<Buisness>()))
.Callback((Buisness bis) => _buisnesses = _buisnesses.Concat(new[] { bis }));
mockBuisnessesDbSet.Setup(x => x.Remove(It.IsAny<Buisness>()))
.Callback((Buisness bis) => _buisnesses = _buisnesses.Where(x => x.Id != bis.Id));
_mockContex = new Mock<ApplicationDbContext>() { CallBase = true };
_mockContex.Setup(x => x.Buisnesses).Returns(mockBuisnessesDbSet.Object);
_buisnessRepository = new BuisnessRepository(_mockContex.Object);
I have no idea what is causing this.