feat(utils): add optional parameter opts to writefile()

Author: broken-pen

lua/orgmode/utils/init.lua

@@ -55,10 +55,12 @@ end
 
 ---@param file string
 ---@param data string|string[]
+---@param opts? {excl?: boolean}
 ---@return OrgPromise<integer> bytes
-function utils.writefile(file, data)
+function utils.writefile(file, data, opts)
   return Promise.new(function(resolve, reject)
-    uv.fs_open(file, 'w', 438, function(err1, fd)
+    local flags = opts and opts.excl and 'wx' or 'w'
+    uv.fs_open(file, flags, 438, function(err1, fd)
       if err1 then
         return reject(err1)
       end

tests/plenary/utils_spec.lua

@@ -124,5 +124,15 @@ describe('Util', function()
       local msg = err:sub(#err - #expected)
       assert.are.equal(expected, msg)
     end)
+
+    it('allows no-clobber writes', function()
+      local promise = utils.writefile(filename, contents, { excl = true })
+      ---@type boolean, string?
+      local ok, err = pcall(promise.wait, promise)
+      assert.is.False(ok)
+      assert(err)
+      local expected = 'EEXIST: file already exists: ' .. filename
+      assert.are.equal(expected, err)
+    end)
   end)
 end)