I needed to do something similar, so I came up with a solution to this.
It s not simple, but once everything is setup you can reuse it across projects. I also have a download of this code on GitHub (https://github.com/johnkoerner/MSTestLooper), but in case that goes away at some point, here is how I did it.
First we create an attribute that we will apply to our class to tell it run all the tests multiple times. Do all of this in a separate assembly, because the DLL needs to live in a special location.
[Serializable]
public class TestLooperAttribute : TestClassExtensionAttribute
{
private static readonly Uri thisGuy = new Uri("urn:TestLooperAttribute");
private string _PropertyName;
public string PropertyName
{
get
{ return _PropertyName; }
set
{
_PropertyName = value;
}
}
public override Uri ExtensionId
{
get {
return thisGuy; }
}
public override TestExtensionExecution GetExecution()
{
return new TestLooperExecution(PropertyName);
}
}
Next we have to create a custom test class execution class:
class TestLooperExecution : TestExtensionExecution
{
private string PropertyName;
public TestLooperExecution(string PropertyName)
{
this.PropertyName = PropertyName;
}
public override ITestMethodInvoker CreateTestMethodInvoker(TestMethodInvokerContext InvokerContext)
{
return new TestLooperInvoker(InvokerContext, PropertyName);
}
public override void Dispose()
{
//TODO: Free, release or reset native resources
}
public override void Initialize(TestExecution Execution)
{
//TODO: Wire up event handlers for test events if needed
}
}
Finally we add a custom invoker, which is where we perform the looping:
class TestLooperInvoker : ITestMethodInvoker
{
private TestMethodInvokerContext m_invokerContext;
private string PropertyName;
public TestLooperInvoker(TestMethodInvokerContext InvokerContext, string PropertyName)
{
m_invokerContext = InvokerContext;
this.PropertyName = PropertyName;
}
public TestMethodInvokerResult Invoke(params object[] args)
{
// Our helper results class to aggregate our test results
HelperTestResults results = new HelperTestResults();
IEnumerable<object> objects = m_invokerContext.TestContext.Properties[PropertyName] as IEnumerable<object>;
foreach (var d in objects)
results.AddTestResult(m_invokerContext.InnerInvoker.Invoke(d), new object[1] { d.GetType().ToString()});
var output = results.GetAllResults();
m_invokerContext.TestContext.WriteLine(output.ExtensionResult.ToString());
return output;
}
}
The HelperTestResults class just builds up strings for output, you can handle this how you want and I don t want to include that code because it will just make this post that much longer.
Compile this into a DLL and then you need to copy it to
C:Program Files (x86)Microsoft Visual Studio 11.0Common7IDEPublicAssemblies
You also have to create a registry entry for the class:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINESOFTWAREWow6432NodeMicrosoftVisualStudio11.0EnterpriseToolsQualityToolsTestTypes{13cdc9d9-ddb5-4fa4-a97d-d965ccfc6d4b}TestTypeExtensionsTestLooperAttribute]
"AttributeProvider"="TestLooper.TestLooperAttribute, TestLooper"
Now that you have all of that done, you can finally use the class:
using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using TestLooper;
using System.Collections.Generic;
namespace UnitTestSamples
{
[TestLooper(PropertyName="strings")]
public class UnitTest1
{
public static List<String> strings = new List<String>();
private TestContext testContextInstance;
public TestContext TestContext
{
get
{
return testContextInstance;
}
set
{
testContextInstance = value;
}
}
[ClassInitialize()]
public static void Init(TestContext x)
{
strings.Add("A");
strings.Add("B");
strings.Add("C");
strings.Add("D");
}
[TestInitialize()]
public void TestInit()
{
if (!TestContext.Properties.Contains("strings"))
testContextInstance.Properties.Add("strings", strings);
}
[TestMethod]
[DataSource("Microsoft.VisualStudio.TestTools.DataSource.CSV", "DataDriven1.csv", "DataDriven1#csv", DataAccessMethod.Sequential)]
[DeploymentItem("DataDriven1.csv")]
public void TestMethodStrings(string s)
{
int value1 = Convert.ToInt32(TestContext.DataRow["Col1"]); ;
TestContext.WriteLine(String.Format("{0}:{1}", s, value1));
}
}
}
Notice that our test method accepts a parameter, which comes from the test looper. I also show this using a data driven test, to show you can combine the two together to generate large permutations across your data sets.