Anything to CSV

AnythingToCs.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;

namespace AnythingToCsv
{
    public static class EnumerableExtensions
    {
         public static StringBuilder ToCsv<T>(this IEnumerable<T> data, params Expression<Func<T, object>>[] columns)
         {
             var columnFuncs = columns.Select(x => x.Compile()).ToList();
             var sb = new StringBuilder();
             sb.AppendLine(GetColumnNames(columns));
             foreach (var row in data)
                 sb.AppendLine(string.Join(",", columnFuncs.Select(func => func(row).ToString())));
             return sb;
         }

        private static string GetColumnNames<T>(IEnumerable<Expression<Func<T, object>>> columns)
        {
            return string.Join(",", columns.Select(x => GetColumnName(x.Body)));
        }

        private static string GetColumnName(Expression expression)
        {
            if (expression is UnaryExpression)
            {
                var operand = ((UnaryExpression)expression).Operand;
                if (operand is MemberExpression)
                    return ((MemberExpression)operand).Member.Name;
                if (operand is MethodCallExpression)
                    return ((MethodCallExpression)operand).Method.Name;
            }
            if (expression is MemberExpression)
            {
                return ((MemberExpression)expression).Member.Name;
            }
            return string.Empty;
        }
    }
}


using System.Collections.Generic;
using AnythingToCsv.Tests.DataStructures;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace AnythingToCsv.Tests
{
    [TestClass]
    public class EnumerableToCsvTests
    {
        [TestMethod]
        public void ToCsv_BuildsExpectedOutput()
        {
            var input = new List<SampleData>
                            {
                                new SampleData
                                    {
                                        IntProp = 1,
                                        StringProp = "One"
                                    },
                                new SampleData
                                    {
                                        IntProp = 2,
                                        StringProp = "Two"
                                    }
                            };

            var result = input.ToCsv(x => x.IntProp, x => x.StringProp);

            const string expected = @"IntProp,StringProp
1,One
2,Two
";

            Assert.AreEqual(expected, result.ToString());
        }
    }
}