public async Task TotalSupplementsCountAsync_WithManufacturerId_ShouldReturnValidSum()
{
// Arrange
FitStoreDbContext database = this.Database;
DatabaseHelper.SeedData(database);
IManufacturerService manufacturerService = new ManufacturerService(database);
// Act
int result = await manufacturerService.TotalSupplementsCountAsync(firstManufacturerId);
// Assert
result.Should().Be(2);
}