TestContext.WriteLine throwing System.FormatException when json string is passed.

[harshjain2]

Description

TestContext.WriteLine throwing System.FormatException when json string is passed.

Method Signature:
public abstract void WriteLine(string format, params object[] args);

Steps to reproduce

• Create a unit test project, add MSTest.TestFramework dll and execute the below test method

[TestClass]
    public class UnitTest1
    {
        private TestContext testContextInstance;
        /// <summary>
        ///Gets or sets the test context which provides
        ///information about and functionality for the current test run.
        ///</summary>
        public TestContext TestContext
        {
            get
            {
                return testContextInstance;
            }
            set
            {
                testContextInstance = value;
            }
        }
        [TestMethod]
        public void TestMethod1()
        {
            var msg = "{curly braces}";
            //Debug.WriteLine(msg);
            TestContext.WriteLine(msg);
        }
    }

Expected behavior

Test sholuld pass, user should be able to write the json in output.

Actual behavior

Test is failing with System.FormatException.

RCA :
This is happening because string.format is used for implementing this API and it expects format which placeholders {0}, {1}, etc. and corresponding arguments.

But when json string is passed, it just throws System.FormatException as string is present inside curly braces.

Workaround:
As a workaround, user has to add one extra curly brace for every curly brace present in string.

string str = "{{mystring}}";

Fix :
Do not use string.format api when count of arguments are null in implementation of API
public abstract void WriteLine(string format, params object[] args);

[AbhitejJohn]

@harshjain2 : This is actually an API with a format and an args. I think the right fix here is to have another API like so
public abstract void WriteLine(string message)
and the user takes care of formatting in any way he/she chooses.

This is similar to how Console.WriteLine works today.
Reference: http://referencesource.microsoft.com/#mscorlib/system/console.cs,2141

[AbhitejJohn]

👍