Neovim Configuration for C# Development

A modular Neovim configuration optimized for C# development using roslyn.nvim, with support for Blazor/Razor files.

Structure

~/.config/nvim/
├── init.lua
├── lua/
│   ├── config/
│   │   ├── options.lua    # Editor settings
│   │   ├── keymaps.lua    # Space as leader + keybindings
│   │   └── lazy.lua       # Plugin manager bootstrap
│   └── plugins/
│       ├── colorscheme.lua  # Tokyonight theme
│       ├── treesitter.lua   # C# + Razor syntax
│       ├── mason.lua        # Tool installer
│       ├── lsp.lua          # roslyn.nvim + rzls.nvim
│       ├── cmp.lua          # Autocompletion
│       ├── fzf.lua          # Fuzzy finding
│       ├── dap.lua          # .NET debugging
│       └── neotest.lua      # Unit testing

Features

• LSP: Full C# language server via roslyn.nvim with inlay hints
• Razor Support: Blazor/Razor development via rzls.nvim
• Debugging: .NET debugging with netcoredbg
• Unit Testing: Test runner with neotest-dotnet
• Autocompletion: nvim-cmp with LSP integration
• Syntax Highlighting: Treesitter for C#, Razor, and more
• Fuzzy Finding: fzf-lua for file/text searching
• Theme: Tokyonight colorscheme

Installation

1. Start Neovim (lazy.nvim will auto-install plugins):

   nvim

2. Install Mason tools:

   :MasonInstall roslyn rzls

3. Verify installation:

   :checkhealth

Prerequisites

• Neovim >= 0.10.0
• .NET SDK (9.0+)
• Git, ripgrep, fzf (for fuzzy finding)
• Node.js and npm (for some LSP features)

Key Keybindings

General

Key	Action
<Space>	Leader key
<leader>w	Save file
<leader>q	Quit
<leader>x	Save and quit
<Esc>	Clear search highlights

Window Navigation

Key	Action
<C-h>	Move to left window
<C-j>	Move to bottom window
<C-k>	Move to top window
<C-l>	Move to right window
<S-h>	Previous buffer
<S-l>	Next buffer

FZF (Fuzzy Finding)

Key	Action
<leader>ff	Find files
<leader>fg	Live grep
<leader>fb	Find buffers
<leader>fh	Help tags
<leader>fo	Recent files
<leader>fc	Commands
<leader>fk	Keymaps

LSP (Language Server)

Key	Action
gd	Go to definition
gD	Go to declaration
gr	Show references
gi	Go to implementation
K	Hover documentation
<leader>ca	Code action
<leader>rn	Rename symbol
<leader>d	Show diagnostics
[d	Previous diagnostic
]d	Next diagnostic

Debugging (DAP)

Key	Action
<F5>	Continue / Start debugging
<F9>	Toggle breakpoint
<F10>	Step over
<F11>	Step into
<F8>	Step out
<leader>dr	Open REPL
<leader>dl	Run last
<leader>dt	Debug nearest test

Testing (Neotest)

Key	Action
<leader>tr	Run nearest test
<leader>tf	Run test file
<leader>ta	Run all tests in solution
<leader>ts	Toggle test summary
<leader>to	Show test output
<leader>dt	Debug nearest test

Completion (in Insert mode)

Key	Action
<C-Space>	Trigger completion
<CR>	Confirm selection
<Tab>	Next item / Expand snippet
<S-Tab>	Previous item
<C-b>	Scroll docs up
<C-f>	Scroll docs down
<C-e>	Abort completion

Usage Examples

Creating a C# Project

cd ~/projects
dotnet new console -n MyApp
cd MyApp
dotnet build
nvim

Debugging

1. Build your project: dotnet build
2. Open a C# file in Neovim
3. Set a breakpoint with F9
4. Start debugging with F5
5. You'll be prompted for the path to the DLL (usually in bin/Debug/net9.0/)

Running Tests

1. Open a test file
2. Position cursor on a test method
3. Run with <leader>tr or debug with <leader>dt

Configuration Customization

All plugin configurations are modular and can be customized by editing files in lua/plugins/.

Changing Editor Settings

Edit lua/config/options.lua to modify:

• Tab size (default: 4 spaces)
• Line numbers
• Search settings
• And more

Adding Custom Keybindings

Edit lua/config/keymaps.lua to add your own keybindings.

Installing Additional Plugins

Create a new file in lua/plugins/ with your plugin configuration:

return {
  "author/plugin-name",
  config = function()
    -- Plugin setup here
  end,
}

Troubleshooting

LSP Not Working

1. Check if roslyn is installed: :Mason
2. Check LSP status: :LspInfo
3. Check health: :checkhealth

Debugging Issues

• Ensure netcoredbg is installed: :Mason
• Verify .NET SDK is installed: dotnet --version
• Check DAP configuration: :lua print(vim.inspect(require('dap').configurations.cs))

Mason Registry Issues

If roslyn or rzls fail to install, ensure the custom registry is configured in lua/plugins/mason.lua:

registries = {
  "github:mason-org/mason-registry",
  "github:Crashdummyy/mason-registry",
}

References

• roslyn.nvim
• rzls.nvim
• Reference Configuration
• lazy.nvim
• Mason