unit-testing.md

title	description	lead	draft	menu	weight	toc
Unit testing	This example shows how unit tests could be constructed for data flow.	This recipe demonstrate how unit tests could be written to test data flows. The described approach here is very basic and should only be considered as a starting point - there are a lot of different possibilities to write unit tests for ETLBox - as the library is written in .NET, all test framework and other test packages are fully supported.	false	recipes parent other	2311	true

Simple unit tests with xunit

namespace ETLBoxTests.DataFlowTests
{
    [Collection("DataFlow")]
    public class UnitTestsSimpleExample
    {

        [Fact]
        public void RowTransformerTest() {
            //Arrange
            RowTransformer transformer = new RowTransformer();
            DataTransferObject testInput = new DataTransferObject() {
                Id = 1,
                Value = "Test"
            };

            //Act
            var result = transformer.ChangeRow(testInput);

            //Assert
            Assert.Equal(1, result.Id);
            Assert.Equal("Adjusted Row (Test)", result.Value);
        }

        [Fact]
        public void NetworkRunnerTest() {
            //Arrange
            NetworkRunner runner = new NetworkRunner();
            var testData = new List<DataTransferObject>() {
                    new DataTransferObject { Id = 1, Value = "TestDataRow 1" },
                    new DataTransferObject { Id = 2, Value = "TestDataRow 2" }
                };

            //Act
            runner.ExecuteFlow(testData);

            //Assert
            Assert.Collection(runner.Result,
                row => { Assert.Equal(1, row.Id); Assert.Equal("Adjusted Row (TestDataRow 1)", row.Value); },
                row => { Assert.Equal(2, row.Id); Assert.Equal("Adjusted Row (TestDataRow 2)", row.Value); }
            );
            Assert.Equal(System.Threading.Tasks.TaskStatus.RanToCompletion, runner.Flow.Destinations.First().Completion.Status);
        }
    }
}

namespace ETLBox.DataFlowTests.Demo
{
    public class DataTransferObject
    {
        public int Id { get; set; }
        public string Value { get; set; }
    }

    public class NetworkRunner
    {
        public ICollection<DataTransferObject> SourceData { get; private set; }
        public ICollection<DataTransferObject> Result => Destination?.Data;
        public Network Flow { get; set; }

        MemorySource<DataTransferObject> Source = new MemorySource<DataTransferObject>();
        MemoryDestination<DataTransferObject> Destination = new MemoryDestination<DataTransferObject>();
        RowTransformation<DataTransferObject> Transformation = new RowTransformation<DataTransferObject>();
        RowTransformer Transformer = new RowTransformer();

        private Network CreateDataflow() {
            Source.Data = SourceData;
            Transformation.TransformationFunc = Transformer.ChangeRow;
            Source.LinkTo(Transformation).LinkTo(Destination);

            return new Network(Source);
        }

        public void ExecuteFlow(ICollection<DataTransferObject> sourceData) {
            SourceData = sourceData;
            Flow = CreateDataflow();
            Flow.Execute();
        }
    }

    public class RowTransformer
    {
        public DataTransferObject ChangeRow(DataTransferObject dto) {
            dto.Value = "Adjusted Row (" + dto.Value + ")";
            return dto;
        }
    }

    public static class App
    {
        public static int Start(string[] args) {
            NetworkRunner runner = new NetworkRunner();
            var prodData = new List<DataTransferObject>() {
                    new DataTransferObject { Id = 1, Value = "ProductionDataRow 1" },
                    new DataTransferObject { Id = 2, Value = "ProductionDataRow 2" }
                };
            runner.ExecuteFlow(prodData);
            return runner.Result.Count > 0 ? 1 : 0;
        }
    }
}

Recommended supporting libraries

• {{< link-ext url="https://github.com/moq/moq4" text="moq - The most popular and friendly mocking library for .NET" >}}. All dataflow compoments implement different interface which can be used for mocking objects.
• {{< link-ext url="https://fluentassertions.com/" text="Fluent assertions" >}}. A very extensive set of extension methods that allow you to more naturally specify the expected outcome of a TDD or BDD-style unit tests.
• {{< link-ext url="https://github.com/WireMock-Net/WireMock.Net" text="Wiremock.NET" >}}. A C# .NET version based on mock4net which mimics the functionality from the Java based Wiremock.org