public async Task CanCreateUser()
{
var result = await userStore.CreateAsync(testUser, default(CancellationToken));
Assert.Equal(IdentityResult.Success, result);
var storedUser = (await usersCollection.FindAsync(u => u.Id == testUser.Id)).Single();
Assert.NotNull(storedUser);
Assert.True(testUser.PropertiesEqual(storedUser));
}