C# parser in F#

parser.cs

using System;
using System.Collections.Generic;

namespace Parser.CSharp
{
    public static class ParserCSharp
    {
        public static string[] ParseCommandline(string input)
        {
            var items = new List<string>();
            var buffer = string.Empty;
            var hold = false;

            foreach (var s in input)
            {
                if (s == '"')
                {
                    if (hold)
                    {
                        items.Add(buffer);
                        buffer = string.Empty;
                        hold = false;
                    }
                    else
                    {
                        hold = true;
                    }
                    continue;
                }

                if (s == ' ' && !hold)
                {
                    if (buffer != string.Empty)
                    {
                        items.Add(buffer);
                    }
                    buffer = string.Empty;
                    continue;
                }

                buffer += s;
            }

            if (buffer != string.Empty)
                items.Add(buffer);

            return items.ToArray();
        }
    }
}

parser.fs

namespace Parser.FSharp

module ParserFSharp =
    type ParseState = { holding: bool; buffer: string; items: string list }

    let addBufferToItems state =
        {state with buffer=""; items=state.buffer :: state.items}

    let parseChar state = 
        function
        | '"' when state.holding ->
            {state with holding=false} |> addBufferToItems
        | '"' ->
            {state with holding=true}
        | ' ' when not state.holding ->
            if state.buffer = "" then state
            else addBufferToItems state
        | c ->
            {state with buffer=state.buffer + (string c)}

    let parseCommandline line =
        let finalState = match (Seq.fold parseChar {holding=false; buffer=""; items = []} line) with
                         | fs when fs.buffer = "" -> fs
                         | fs -> addBufferToItems fs
        List.rev finalState.items

tests.cs

using System;
using System.Collections.Generic;
using Parser.CSharp;
using Parser.FSharp;
using Xunit;

namespace Parser.Tests
{
    class DataSource {
        private static List<object[]> data = new List<object[]> {
            new object[] { "help", new[] { "help" } },
            new object[] { "help user", new[] { "help", "user" } },
            new object[] { "user change-password admin P@55-w0rd!1", new[] { "user", "change-password", "admin", "P@55-w0rd!1" } },
            new object[] { "user change-name admin \"Aaron Powell\"", new[] { "user", "change-name", "admin", "Aaron Powell" } }
        };

        public static IEnumerable<object[]> TestData
        {
            get { return data; }
        }
    }

    public class ParserTests
    {
        [Theory]
        [MemberData(nameof(DataSource.TestData), MemberType = typeof(DataSource))]
        public void RunTests_CSharp(string key, string[] value)
        {
            var result = ParserCSharp.ParseCommandline(key);
            Assert.Equal(value, result);
        }

        [Theory]
        [MemberData(nameof(DataSource.TestData), MemberType = typeof(DataSource))]
        public void RunTests_FSharp(string key, string[] value)
        {
            var result = ParserFSharp.parseCommandline(key);
            Assert.Equal(value, result);
        }
    }
}