test(treesitter): add benchmark #18989

add benchmark from #18109

test/benchmark/treesitter_spec.lua

@@ -0,0 +1,53 @@
+local helpers = require('test.functional.helpers')(after_each)
+
+local clear = helpers.clear
+local exec_lua = helpers.exec_lua
+
+describe('treesitter perf', function()
+
+  setup(function()
+    clear()
+  end)
+
+  it('can handle large folds', function()
+    helpers.command'edit ./src/nvim/eval.c'
+    exec_lua[[
+      local parser = vim.treesitter.get_parser(0, "c", {})
+      vim.treesitter.highlighter.new(parser)
+
+      local function keys(k)
+        vim.api.nvim_feedkeys(k, 't', true)
+      end
+
+      vim.opt.foldmethod = "manual"
+      vim.opt.lazyredraw = false
+
+      vim.cmd '1000,7000fold'
+      vim.cmd '999'
+
+      local function mk_keys(n)
+        local acc = ""
+        for _ = 1, n do
+          acc = acc .. "j"
+        end
+        for _ = 1, n do
+          acc = acc .. "k"
+        end
+
+        return "qq" .. acc .. "q"
+      end
+
+      local start = vim.loop.hrtime()
+      keys(mk_keys(10))
+
+      for _ = 1, 100 do
+        keys "@q"
+        vim.cmd'redraw!'
+      end
+
+      return vim.loop.hrtime() - start
+    ]]
+
+  end)
+
+end)