NeoVim + C#: Improving the Debugging Experience

The recent dap/debugging experience is not 100% optimal. We still manually install netcoredbg and choose the DLL when debugging our csharp code.

We will fix both issues in this article.

Fix netcoredb installation and reference

install netcoredbg with Mason

-- lua/plugins/init.lua
-- ...
{
    "williamboman/mason.nvim",
    opts = {
      ensure_installed = {
        "netcoredbg",
      },
    },
}

use netcoredbg from Mason

-- lua/configs/nvim-dap.lua
-- ...

local mason_path = vim.fn.stdpath("data") .. "/mason/packages/netcoredbg/netcoredbg"
-- local explicit_path = "$HOME/Documents/debuggers/netcoredbg/netcoredbg"

local netcoredbg_adapter = {
  type = "executable",
  command = mason_path,
  args = { "--interpreter=vscode" },
}

dap.adapters.netcoredbg = netcoredbg_adapter -- needed for normal debugging
dap.adapters.coreclr = netcoredbg_adapter    -- needed for unit test debugging

Autodetect The DLL

Create new lua module for dll auto detection: lua/configs/nvim-dap-dotnet.lua

-- lua/configs/nvim-dap-dotnet.lua

local M = {}

-- Find the root directory of a .NET project by searching for .csproj files
function M.find_project_root_by_csproj(start_path)
  local Path = require("plenary.path")
  local path = Path:new(start_path)

  while true do
    local csproj_files = vim.fn.glob(path:absolute() .. "/*.csproj", false, true)
    if #csproj_files > 0 then
      return path:absolute()
    end

    local parent = path:parent()
    if parent:absolute() == path:absolute() then
      return nil
    end

    path = parent
  end
end

-- Find the highest version of the netX.Y folder within a given path.
function M.get_highest_net_folder(bin_debug_path)
  local dirs = vim.fn.glob(bin_debug_path .. "/net*", false, true) -- Get all folders starting with 'net' in bin_debug_path

  if dirs == 0 then
    error("No netX.Y folders found in " .. bin_debug_path)
  end

  table.sort(dirs, function(a, b) -- Sort the directories based on their version numbers
    local ver_a = tonumber(a:match("net(%d+)%.%d+"))
    local ver_b = tonumber(b:match("net(%d+)%.%d+"))
    return ver_a > ver_b
  end)

  return dirs[1]
end

-- Build and return the full path to the .dll file for debugging.
function M.build_dll_path()
  local current_file = vim.api.nvim_buf_get_name(0)
  local current_dir = vim.fn.fnamemodify(current_file, ":p:h")

  local project_root = M.find_project_root_by_csproj(current_dir)
  if not project_root then
    error("Could not find project root (no .csproj found)")
  end

  local csproj_files = vim.fn.glob(project_root .. "/*.csproj", false, true)
  if #csproj_files == 0 then
    error("No .csproj file found in project root")
  end

  local project_name = vim.fn.fnamemodify(csproj_files[1], ":t:r")
  local bin_debug_path = project_root .. "/bin/Debug"
  local highest_net_folder = M.get_highest_net_folder(bin_debug_path)
  local dll_path = highest_net_folder .. "/" .. project_name .. ".dll"

  print("Launching: " .. dll_path)
  return dll_path
end

return M

Adjust nvim-dap.lua to use the new lua file

-- lua/configs/nvim-dap.lua
-- ...

local dotnet = require("configs.nvim-dap-dotnet")

dap.configurations.cs = {
  {
-- ...
    program = function()
      return dotnet.build_dll_path()
    end
}
}