How do I access ITaskItem meta data from with my MSBuild script?

Question

I have a custom Build task that returns ITaskTem[] as output to my build script. I cannot find an documentation/examples on how I can access these values from with in my MSBuild script.

My Execute method calls this private method which returns the array. I would like to be able to iterate through the Output and get both the TaskItem ItemSpec and the "Message" metadata item. How can I do this?

[Output]
    public ITaskItem[] FailedTestsResults { get; set; }

...

 private ITaskItem[] GetFailedTests(TestResultsSummary testResultsSummary)
    {          
       IList<TestResult> testList = testResultsSummary.Tests.ToList();
       IEnumerable<TestResult> failedTests = testList.Where(x => !x.Passed);
        IList<ITaskItem> failedTestsTaskItems = new List<ITaskItem>();
        foreach (var failedTest in failedTests)
        {

                //test encountered enexpected error.
                ITaskItem failTestItem = new TaskItem(failedTest.TestName);
                failTestItem.SetMetadata("Message", failedTest.Message);
                failedTestsTaskItems.Add(failTestItem);
        }
        return (ITaskItem[]) failedTestsTaskItems.ToArray();
    }

Answer 1

I figured it out. Metadata can be accessed like so..

 <Message Text="Failed: %(FailedTests.Identity) => %(FailedTests.Message)" />

Notice the use of '%' rather than '$'.