ApplicationUsersControllerGetApplicationUser.cs

[Fact]
public async Task DoesReturnOk_GivenUserExists()
{
    // Arrange
    var user = new ApplicationUser
    {
        Id = "123",
        Email = "test@test.com"
    };

    _context.Users.Add(user);
    _context.SaveChanges();

    // Act
    var response = await _client.GetAsync($"/api/ApplicationUsers/{user.Id}");

    // Assert
    Assert.Equal(HttpStatusCode.OK, response.StatusCode);
    string jsonResult = await response.Content.ReadAsStringAsync();
    ApplicationUser userFromJson = JsonConvert.DeserializeObject<ApplicationUser>(jsonResult);
    Assert.Equal(user.Id, userFromJson.Id);
    Assert.Equal(user.Email, userFromJson.Email);
}