DEATH TO ALL FALSE COMMENTS

gistfile1.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using NUnit.Framework;

namespace rostest
{
    [TestFixture]
    public class Class1
    {
        private CommentHoover _hoover;

        [SetUp]
        public void Setup()
        {
            _hoover = new CommentHoover();
        }

        [Test]
        public void Clean_GivenSingleNarrativeComment_KeepsComment()
        {
            var code = "// comment";

            var output = _hoover.Clean(code);

            Assert.That(output, Is.EqualTo(code));
        }

        [Test]
        public void Clean_GivenSingleLineOfCode_ReturnsSame()
        {
            var code = "Console.WriteLine(\"hi\");";

            var output = _hoover.Clean(code);

            Assert.That(output, Is.EqualTo(code));
        }

        [TestCase("// Console.WriteLine(\" hi \");")]
        [TestCase("// Debug.WriteLine(\" hi \");")]
        //[TestCase("// Some.Api(\" hi \");")]
        public void Clean_GivenSingleCommentOfCodeWithQuotedWord_RemovesComment(string code)
        {
            var output = _hoover.Clean(code);

            Assert.That(output, Is.Empty);
        }

        [Test]
        public void Clean_GivenCommentAndCodeLine_ReturnsJustCodeLine()
        {
            var code = "Console.WriteLine(\"hi\");" + Environment.NewLine +
                       "//Console.WriteLine(\"hi\");";

            var output = _hoover.Clean(code);

            Assert.That(output, Is.EqualTo("Console.WriteLine(\"hi\");"));
        }

        [Test]
        public void Clean_GivenCodeWithNarrativeComment_ReturnsBothLines()
        {
            var code = "// Performs a console writeline" + Environment.NewLine +
                       "Console.WriteLine(\"hi\");";

            var output = _hoover.Clean(code);

            Assert.That(output, Is.EqualTo(code));
        }

        [Test]
        public void Clean_GivenCodeWithCommentBlock_CleansBlock()
        {
            var code = "/* Console.WriteLine(\"hi\");" + Environment.NewLine +
                       "Console.WriteLine(\"hi\");" + Environment.NewLine +
                       "*/" + Environment.NewLine +
                       "Console.WriteLine(\"yay\");";

            var output = _hoover.Clean(code);

            Assert.That(output, Is.EqualTo("Console.WriteLine(\"yay\");"));
        }

        [Test]
        public void Clean_GivenCodeWithXDoc_KeepsComment()
        {
            var code = "/// <summary>a</summary>" + Environment.NewLine +
                       "public static void Main() { }";

            var output = _hoover.Clean(code);

            Assert.That(output, Is.EqualTo(code));
        }
    }

    public class CommentHoover
    {
        private static readonly string[] Words;

        static CommentHoover()
        {
            Words = File.ReadAllLines("words.txt").Select(x=>x.ToLower()).ToArray();
        }

        public string Clean(string code)
        {
            var removals = new List<string>();

            List<string> captureBuffer = null;
            var lines = code.Split(new[] { Environment.NewLine }, StringSplitOptions.None);
            foreach (var line in lines)
            {
                var trimmed = line.Trim();

                if (StartCapture(trimmed))
                {
                    captureBuffer = new List<string>();
                }

                if (captureBuffer != null)
                {
                    if (!CommentIsEnglish(line)
                        && !CommentIsXDoc(line))
                    {
                        captureBuffer.Add(line);
                    }
                }

                if (EndCapture(trimmed))
                {
                    if (captureBuffer.Any())
                    {
                        removals.Add(string.Join(Environment.NewLine, captureBuffer));
                    }

                    captureBuffer = null;
                }
            }

            return removals.Aggregate(code, (current, removal) => current.Replace(removal, ""))
                           .Trim();
        }

        private bool CommentIsXDoc(string line)
        {
            return line.StartsWith("///");
        }

        private static bool StartCapture(string trimmed)
        {
            return trimmed.StartsWith("/*") || trimmed.StartsWith("//");
        }

        private static bool EndCapture(string trimmed)
        {
            return trimmed.StartsWith("//") || trimmed.EndsWith("*/");
        }

        private static bool CommentIsEnglish(string line)
        {
            var commentWords = line.ToLower().Split(' ');
            return commentWords.Any(word => Words.Contains(word))
                   && !line.Contains("WriteLine");
        }
    }
}