better-unit-test-in-c#-article-FillBoxTest.cs

better-unit-test-in-c#-article-FillBoxTest.cs

public static class FillBoxTest
{
  public sealed record Args
  {
    public IBox Box { get; init; } = null!;
    public Dictionary<string, Thing> LabelsAndThings { get; init; } = new();
    public WriteLog WriteLog { get; init; } = null!;
  }

  sealed class TestCases : IEnumerable<object[]>
  {
    public IEnumerator<object[]> GetEnumerator()
    {
      yield return BoxAndLabelsAndThings_OpenBoxThenPutThingInsideThenCloseBoxAndWriteLogs_ThingsWithLabelEndedWithIgnoreExpected_1();
    }

    static object[] BoxAndLabelsAndThings_OpenBoxThenPutThingInsideThenCloseBoxAndWriteLogs_ThingsWithLabelEndedWithIgnoreExpected_1()
    {
      var writeLogMock = new Mock<WriteLog>(MockBehavior.Strict);
      var boxMock = new Mock<IBox>(MockBehavior.Strict);

      var mockSequence = new MockSequence();

      boxMock.InSequence(mockSequence).Setup(box => box.Open());
      writeLogMock.InSequence(mockSequence).Setup(writeLog => writeLog("The box is opened."));
      boxMock.InSequence(mockSequence).Setup(box => box.PutInside(new Thing { Size = 1 }, "Label 1")).Returns(true);
      boxMock.InSequence(mockSequence).Setup(box => box.PutInside(new Thing { Size = 2 }, "Label 2 Ignore")).Returns(false);
      boxMock.InSequence(mockSequence).Setup(box => box.PutInside(new Thing { Size = 3 }, "Label 3")).Returns(true);
      boxMock.InSequence(mockSequence).Setup(box => box.Close());
      writeLogMock.InSequence(mockSequence).Setup(writeLog => writeLog("The box is closed."));

      var args = new Args
      {
          Box = boxMock.Object,
          LabelsAndThings = new Dictionary<string, Thing>
          {
              { "Label 1", new Thing { Size = 1 } },
              { "Label 2 Ignore", new Thing { Size = 2 } },
              { "Label 3", new Thing { Size = 3 } },
          },
          WriteLog = writeLogMock.Object
      };

      var expected = new Dictionary<string, Thing>
      {
          { "Label 2 Ignore", new Thing { Size = 2 } },
      };

      return new object[] { args, expected };
    }

    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
  }

  [Theory]
  [ClassData(typeof(TestCases))]
  public static void Test(
    Args args,
    Dictionary<string, Thing> expected)
  {
    var actual = Operations.FillBox(args.Box, args.LabelsAndThings, args.WriteLog);
    Assert.Equal(expected, actual);
  }
}