Tag: Extension Methods

A very common scenario that developers/testers encounter when writing data driven tests is to print input parameters from data sources. Data driven test can encompass many data sources (sql, .csv, excel, .xml, etc…) and Yes, I was even able to extend MSTests functionality by passing my own custom collection:

MSTEST: EXTENDING DATA DRIVEN TESTS TO USE IENUMERABLE<OBJECT> AS THE DATA SOURCE

https://dondeetan.com/2016/02/18/mstest-extending-data-driven-tests-to-use-ienumerableobject-as-the-data-source/

While there are many implementations to solve this, I wanted to provide (in my opinion) the most easiest and efficient way possible for developers and testers to print out input parameters without leaving the context during test development. Thus, extension methods. What are extension methods? In a high level, extension methods allows you to “extend” or “add” methods to existing types (even types built in the .Net framework) without creating a new class from the derived type. Click here on Extension Methods (C# Programming Guide) more information.

Now that we have good understanding of extension methods, then why not extend the TestContext class which contains all information during test execution? TestContext also contains information around the datarow and datacolumn passed during data driven testing. It’s a simple as calling the datarow during runtime.

TestContext.DataRow["Description"].ToString();

TestConext.DataRow has a property “Table” which you can get all columns during the instance of test execution. At this point, all you need to do is extend TestContext to print input parameters.

public static class Helper
    {
        public static void PrintInput(this TestContext testContext)
        {
            Console.WriteLine($"Total Input Fields: {testContext.DataRow.Table.Columns.Count}");
            var columns = testContext.DataRow.Table.Columns;
            for (var i = 0; i < columns.Count; i++)
            {
                Console.WriteLine($"Field: {columns[i].ColumnName} Value: {testContext.DataRow[i]}");
            }
        }
    }

In your Test Method, all you have to do is just call one line of code:

TestContext.PrintInput();

And the results from that instance test execution:

Great way to show input parameters for debugging purposes!