Join StringCollection with commas

Question

Usually, joining a List with commas is easy using string.Join(). However, coming across a StringCollection today, string.Join() outputs "System.Collections.Specialized.StringCollection" output instead of a comma-separated string.

    [TestMethod]
    public void TestJoin()
    {
        StringCollection stringCollection = new StringCollection() { "Denis", "Jason", "Shawn" };
        // Microsoft.VisualStudio.TestTools.UnitTesting.AssertFailedException:
        // 'Assert.AreEqual failed. Expected:<Denis, Jason, Shawn>. Actual:<System.Collections.Specialized.StringCollection>.'
        Assert.AreEqual("Denis, Jason, Shawn", string.Join(", ", stringCollection));
    }

How do we Join() a StringCollection?

Answer 1

It is possible to convert the StringCollection to a List collection first: https://stackoverflow.com/a/844420/4682228.

var commaSeparatedList = string.Join(", ", stringCollection.Cast<string>());