Regex to remove queries with no value

public string TrimEmptyQueries(string queryString)
{
    var result = Regex.Replace(queryString, @"(?<=\&|\?)([^\&\n\=]+|[^\&\n]+\=)(?>&|$)", "")
                            .Trim('&');
    return result == "?" ? "" : result;
}

public void Main()
{
    var testData = new[]
    {
        new TestData("?foo=foo&bar&foobar&blah=blah&bleh&hi&bye&asdf&", "?foo=foo&blah=blah"),
        new TestData("?foo=foo&bar=&foobar=foobar", "?foo=foo&foobar=foobar"),
        new TestData("?foo=foo&bar&foobar=foobar", "?foo=foo&foobar=foobar"),
        new TestData("?foo=foo&bar=bar", "?foo=foo&bar=bar"),
        new TestData("?foo=foo", "?foo=foo"),
        new TestData("?foo=foo&bar", "?foo=foo"),
        new TestData("?foo=foo&bar=", "?foo=foo"),
        new TestData("?bar&foo=foo", "?foo=foo"),
        new TestData("?bar=&foo=foo", "?foo=foo"),
        new TestData("?foo=", ""),
        new TestData("?foo", "")
    };

    foreach (var test in testData)
    {
        var result = TrimEmptyQueries(test.InitialValue);
        Console.WriteLine("===============================================================================");
        Console.WriteLine("'{0}' {1}", test.InitialValue, " should be");
        Console.WriteLine("'{0}' {1}", test.ExpectedValue, " and is");
        Console.WriteLine("'{0}'", result);
        Console.WriteLine(result == test.ExpectedValue ? "Passed" : "Failed");
    }
}

public class TestData
{
    public string InitialValue { get; set; }
    public string ExpectedValue { get; set; }

    public TestData(string initialValue, string expectedValue)
    {
        InitialValue = initialValue;
        ExpectedValue = expectedValue;
    }
}