🔧 Writing XUnit Tests without Object Arrays

public enum FoodType { Fruit, Fast }

public interface IFoodService
{
    public IEnumerable<string> GetByType(FoodType type);
}

public class FoodService : IFoodService
{
    public IEnumerable<string> GetByType(FoodType type) => type switch
    {
        FoodType.Fruit => ["Apple", "Banana"],
        FoodType.Fast => ["Pizza", "Burger"],
        _ => throw new NotImplementedException()
    };
}

public class FoodTests
{
    // override ToString method allow us to specify name for individual tests in TheoryData<T>
    public record FoodTestData(FoodType Type, IEnumerable<string> Expected, string TestName)
    {
        public override string ToString() => TestName;
    }

    // this method has the input parameters and expected values. we can scale this method with more tests without changes the test itself.
    public static TheoryData<FoodTestData> GetFoodTestData() => [
        new(Type: FoodType.Fruit, Expected: ["Apple","Banana"], TestName: "Test should return expected fruits"),
        new(Type: FoodType.Fast, Expected: ["Pizza","Burger"], TestName: "Test should return expected fast food")
    ];

    [Theory]
    [MemberData(nameof(GetFoodTestData))]
    public void ShouldReturnExpectedFood(FoodTestData foodTestData)
    {
        // Arrange
        var mockFoodService = new Mock<IFoodService>();
        mockFoodService
            .Setup(x => x.GetByType(FoodType.Fruit))
            .Returns(["Apple", "Banana"]);

        // Act
        var food = new FoodService().GetByType(foodTestData.Type);

        // Assert
        Assert.Equal(foodTestData.Expected, food);
    }
}