Creating Inline Data Driven Tests in xUnit

xUnit.net allows the creation of data-driven tests. These kind of tests get their test data from outside the test method code via parameters added to the test method signature.

Say we had to test a Calculator class and check it’s add method returned the correct results for six different test cases. Without data-driven tests we’d either have to write six separates tests (with almost identical code) or some loop inside our test method containing an assert.

Regular xUnit.net test methods are identified by applying the [Fact] attribute. Data-driven tests instead use the [Theory] attribute.

To get data-driven features and the [Theory] attribute, install the xUnit.net Extensions NuGet package in addition to the standard xUnit.net package.

Creating Inline Data-Driven Tests

The [InlineData] attribute allows us to specify test data that gets passed to the parameters of test method.

So for our Calculator add test we’d start by defining the test method:

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New Pluralsight Course: The xUnit.net Testing Framework

My latest Pluralsight course on the xUnit.net testing framework has just been released.

Course Description

Learn the latest in unit testing technology for C#, VB.NET (and other .NET languages) created by the original inventor of NUnit.

xUnit.net is a free, extensible, open source framework designed for programmers that aligns more closely with the .NET platform.

 

You can check it out now on Pluralsight.com.

Asserting the Results of Tests in xUnit.net

The below is an excerpt from the latest chapter “An Introduction to Unit Testing With xUnit.net” from my book Keeping Software Soft.

 

xUnit.net provides a number of ways for checking (asserting) results are as expected.


The following explanatory tests shown the different types of assertions that xUnit.net supports:

using System;
using System.Collections.Generic;
using Xunit;

namespace KeepingSoftwareSoftSamples.XUnitTestingDemo
{
    public class XUnitAssertExamples
    {
        [Fact]
        public void SimpleAssertsThatOneValueEqualsAnother()
        {
            Assert.Equal(1, 2); // fail
            Assert.Equal("hello", "hello"); // pass

            Assert.NotEqual(1, 2); // pass
            Assert.NotEqual("hello", "hello"); // fail
        }

        [Fact]
        public void BooleanAsserts()
        {
            Assert.True(true); // pass
            Assert.True(false); // fail

            Assert.False(false); // pass
            Assert.False(true); // fail

            // Don't do this
            Assert.True(1 == 1); // pass
        }

        [Fact]
        public void Ranges()
        {
            const int value = 22;

            Assert.InRange(value, 21, 100); // pass
            Assert.InRange(value, 22, 100); // pass

            Assert.NotInRange(value, 999, 99999); // pass

            Assert.InRange(value, 23, 100); // fail
        }

        [Fact]
        public void Nulls()
        {
            Assert.Null(null); // pass

            Assert.NotNull("hello"); // pass

            Assert.NotNull(null); // fail
        }

        [Fact]
        public void ReferenceEquality()
        {
            var objectA = new Object();
            var objectB = new Object();

            Assert.Same(objectA, objectB); // fail

            Assert.NotSame(objectA, objectB); // pass
        }

        [Fact]
        public void AnIEnumberableContainsASpecificItem()
        {
            var days = new List<string>
                                 {
                                     "Monday",
                                     "Tuesday"
                                 };

            Assert.Contains("Monday", days); // pass
            Assert.Contains("Friday", days); // fail

            Assert.DoesNotContain("Friday", days); // pass
        }

        [Fact]
        public void IEnumerableEmptiness()
        {
            var aCollection = new List<string>();

            Assert.Empty(aCollection); // pass

            aCollection.Add("now no longer empty");

            Assert.NotEmpty(aCollection); // pass

            Assert.Empty(aCollection); // fail            
        }

        [Fact]
        public void IsASpecificType()
        {
            Assert.IsType<string>("hello"); // pass

            Assert.IsNotType<int>("hello"); // pass

            Assert.IsType<int>("hello"); // fail
        }

        [Fact]
        public void IsAssignableFrom()
        {
            const string stringVariable = "42";

            Assert.IsAssignableFrom<string>(stringVariable); // pass

            Assert.IsAssignableFrom<int>(stringVariable); // fail
        }
    }
}

To learn more about xUnit.net check out my Pluralsight course: The xUnit.net testing framework. Also check out my xUnit.net cheat sheet.

Quick-Start Guide To Using xUnit To Test Your Windows 8 WinRT Store app

Until xUnit officially supports* Windows store apps you can get xUnit working with your WinRT app by doing the following:

In Visual Studio 2012, go to Tools menu, Extensions and Updates; search for and install “xUnit.net runner for Visual Studio 2012”.

xUnitRunner

In Visual Studio 2012, go to Tools menu, Extensions and Updates; search for and install “xUnit Test Library Template”.

xUnitTemplate

You may have to restart Visual Studio…

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