test: opening directories with netrw works by default

tests/yazi/open_dir_with_defaults_spec.lua

@@ -0,0 +1,25 @@
+local assert = require('luassert')
+local mock = require('luassert.mock')
+
+local api_mock = mock(require('yazi.vimfn'))
+
+local plugin = require('yazi')
+
+describe(
+  'when the user has not set open_for_directories and uses the defaults',
+  function()
+    after_each(function()
+      mock.clear(api_mock)
+    end)
+
+    it('does not show yazi when a directory is opened', function()
+      ---@diagnostic disable-next-line: missing-fields
+      plugin.setup()
+
+      -- instead of netrw opening, yazi should open
+      vim.api.nvim_command('edit /')
+
+      assert.stub(api_mock.termopen).was_not_called()
+    end)
+  end
+)