diff --git a/lazy-lock.json b/lazy-lock.json
index 5932098..094b022 100644
--- a/lazy-lock.json
+++ b/lazy-lock.json
@@ -28,6 +28,7 @@
   "mason.nvim": { "branch": "main", "commit": "2a6940af80375532e5e9e7c1f2fc6319a1b7a69d" },
   "neotest": { "branch": "master", "commit": "27bf921498043f7ecd821d6db68d05de244bbd02" },
   "neotest-golang": { "branch": "main", "commit": "05cd7bf89a146cf1fa2848a9fe277a1e68a3a51d" },
+  "neotest-vitest": { "branch": "main", "commit": "b0c265743c877058068dbc40d104ea5d40e6b257" },
   "neotest-vstest": { "branch": "main", "commit": "de30c7978937d07e6d29ab7807a00fad1c61120b" },
   "nvim-autopairs": { "branch": "master", "commit": "3172f40c16563db871a58f20d205c710ad782311" },
   "nvim-cmp": { "branch": "main", "commit": "2ffe79f1f021def8dd1fcd81deb16f1bb0d989f3" },
diff --git a/lua/simonkdev/lazy/testing.lua b/lua/simonkdev/lazy/testing.lua
index cbe4c90..74e9926 100644
--- a/lua/simonkdev/lazy/testing.lua
+++ b/lua/simonkdev/lazy/testing.lua
@@ -1,3 +1,66 @@
+-- neotest-vitest assumes Unix paths. On Windows it runs node_modules/.bin/vitest, a shell script Windows can't
+-- start, mixes C:/ and C:\ paths, and can't find the project's config: tests aren't found when Neovim was started
+-- above the project (e.g. at a monorepo root), tests that use Vitest globals fail, and every result reads as
+-- failed (marilari88/neotest-vitest#90; the unmerged fix #74 covers only the last part). These patches use
+-- Windows paths throughout; drop them once upstream handles Windows.
+local function vitest_adapter()
+	local adapter = require("neotest-vitest")
+	if vim.fn.has("win32") == 0 then
+		return adapter({})
+	end
+
+	local function native(path)
+		return (path:gsub("^%a:", string.upper):gsub("/", "\\"))
+	end
+
+	local root = adapter.root
+	adapter.root = function(path)
+		local dir = root(path)
+		return dir and native(dir)
+	end
+
+	local util = require("neotest-vitest.util")
+	local to_results = util.parsed_json_to_results
+	util.parsed_json_to_results = function(data, ...)
+		for _, file in pairs(data.testResults or {}) do
+			file.name = native(file.name)
+		end
+		return to_results(data, ...)
+	end
+
+	return adapter({
+		vitestCommand = function(path)
+			for dir in vim.fs.parents(path) do
+				local bin = vim.fs.joinpath(dir, "node_modules", ".bin", "vitest.cmd")
+				if vim.uv.fs_stat(bin) then
+					return bin
+				end
+			end
+			return "vitest"
+		end,
+		-- It finds the project with a {vite,vitest}.config.* glob, and Windows glob has no braces. Run from the
+		-- package directory instead, where Vitest picks up vite.config.ts (globals etc.) itself.
+		cwd = function(path)
+			return vim.fs.root(path, "package.json")
+		end,
+	})
+end
+
+-- neotest parses test files in a child Neovim started with -u NONE, which never loads nvim-treesitter's filetype
+-- aliases (typescriptreact -> tsx), so .tsx test files show no tests (nvim-neotest/neotest#630, #631). Adding
+-- nvim-treesitter to the child's runtimepath fixes it: neotest's add_paths_to_rtp sources plugin/filetypes.lua.
+local function load_treesitter_aliases_in_subprocess()
+	local subprocess = require("neotest.lib").subprocess
+	local init = subprocess.init
+	subprocess.init = function(...)
+		init(...)
+		local treesitter = require("lazy.core.config").plugins["nvim-treesitter"]
+		if subprocess.enabled() and treesitter then
+			subprocess.add_paths_to_rtp({ treesitter.dir })
+		end
+	end
+end
+
 return {
 	{
 		"nvim-neotest/neotest",
@@ -8,8 +71,10 @@ return {
 			"nvim-treesitter/nvim-treesitter",
 			"Nsidorenco/neotest-vstest",
 			{ "fredrikaverpil/neotest-golang", version = "^2" },
+			"marilari88/neotest-vitest",
 		},
 		config = function()
+			load_treesitter_aliases_in_subprocess()
 			require("neotest").setup({
 				adapters = {
 					require("neotest-vstest")({
@@ -18,6 +83,7 @@ return {
 					}),
 					require("neotest-golang")(), -- debugs tests through nvim-dap-go
 					require("rustaceanvim.neotest"), -- debugs tests through codelldb
+					vitest_adapter(),
 				},
 				status = { virtual_text = true },
 				output = {
diff --git a/tests/smoke.lua b/tests/smoke.lua
index 520cdce..b9e9f3f 100644
--- a/tests/smoke.lua
+++ b/tests/smoke.lua
@@ -203,6 +203,14 @@ local function run()
 			vim.api.nvim_buf_delete(buf, { force = true })
 		end
 
+		-- Every language has a test adapter; a missing one leaves <leader>T… silently finding no tests.
+		local adapters = vim.tbl_map(function(a)
+			return a.name
+		end, require("neotest.config").adapters)
+		for _, name in ipairs({ "neotest-vstest", "neotest-golang", "rustaceanvim", "neotest-vitest" }) do
+			check(vim.list_contains(adapters, name), "neotest has no " .. name .. " adapter")
+		end
+
 		-- Files without a formatter (and C#, after Roslyn) are trimmed on save; patches are left alone.
 		check(vim.tbl_contains(conform.formatters_by_ft.cs, "trim_whitespace"), "cs buffers aren't trimmed")
 		local input = { " a ", "", "" }