test: :file {name}

test/functional/ex_cmds/file_spec.lua

@@ -0,0 +1,35 @@
+local helpers = require('test.functional.helpers')(after_each)
+local lfs = require('lfs')
+local clear = helpers.clear
+local command = helpers.command
+local eq = helpers.eq
+local funcs = helpers.funcs
+local rmdir = helpers.rmdir
+
+describe(':file', function()
+  local swapdir = lfs.currentdir()..'/Xtest-file_spec'
+  before_each(function()
+    clear()
+    rmdir(swapdir)
+    lfs.mkdir(swapdir)
+  end)
+  after_each(function()
+    command('%bwipeout!')
+    rmdir(swapdir)
+  end)
+
+  it("rename does not lose swapfile #6487", function()
+    local testfile = 'test-file_spec'
+    local testfile_renamed = testfile..'-renamed'
+    -- Note: `set swapfile` *must* go after `set directory`: otherwise it may
+    -- attempt to create a swapfile in different directory.
+    command('set directory^='..swapdir..'//')
+    command('set swapfile fileformat=unix undolevels=-1')
+
+    command('edit! '..testfile)
+    -- Before #6487 this gave "E301: Oops, lost the swap file !!!" on Windows.
+    command('file '..testfile_renamed)
+    eq(testfile_renamed..'.swp',
+       string.match(funcs.execute('swapname'), '[^%%]+$'))
+  end)
+end)

test/functional/helpers.lua

@@ -32,20 +32,15 @@ local nvim_set  = 'set shortmess+=I background=light noswapfile noautoindent'
                   ..' belloff= noshowcmd noruler nomore'
 local nvim_argv = {nvim_prog, '-u', 'NONE', '-i', 'NONE', '-N',
                    '--cmd', nvim_set, '--embed'}
-
+-- Directory containing nvim.
-local mpack = require('mpack')
-
-local tmpname = global_helpers.tmpname
-local uname = global_helpers.uname
-
--- Formulate a path to the directory containing nvim.  We use this to
--- help run test executables.  It helps to keep the tests working, even
--- when the build is not in the default location.
 local nvim_dir = nvim_prog:gsub("[/\\][^/\\]+$", "")
 if nvim_dir == nvim_prog then
   nvim_dir = "."
 end
 
+local mpack = require('mpack')
+local tmpname = global_helpers.tmpname
+local uname = global_helpers.uname
 local prepend_argv
 
 if os.getenv('VALGRIND') then