Merge pull request #18357 from bfredl/ui_stdin

feat(ui): allow embedder to emulate "cat data | nvim -" behaviour

test/functional/helpers.lua

@@ -361,14 +361,15 @@ local function remove_args(args, args_rm)
   return new_args
 end
 
-function module.spawn(argv, merge, env, keep)
+--- @param io_extra used for stdin_fd, see :help ui-option
+function module.spawn(argv, merge, env, keep, io_extra)
   if session and not keep then
     session:close()
   end
 
   local child_stream = ChildProcessStream.spawn(
       merge and module.merge_args(prepend_argv, argv) or argv,
-      env)
+      env, io_extra)
   return Session.new(child_stream)
 end
 
@@ -415,8 +416,8 @@ end
 --    clear('-e')
 --    clear{args={'-e'}, args_rm={'-i'}, env={TERM=term}}
 function module.clear(...)
-  local argv, env = module.new_argv(...)
-  module.set_session(module.spawn(argv, nil, env))
+  local argv, env, io_extra = module.new_argv(...)
+  module.set_session(module.spawn(argv, nil, env, nil, io_extra))
 end
 
 -- Builds an argument list for use in clear().
@@ -426,6 +427,7 @@ function module.new_argv(...)
   local args = {unpack(module.nvim_argv)}
   table.insert(args, '--headless')
   local new_args
+  local io_extra
   local env = nil
   local opts = select(1, ...)
   if type(opts) == 'table' then
@@ -461,13 +463,14 @@ function module.new_argv(...)
       end
     end
     new_args = opts.args or {}
+    io_extra = opts.io_extra
   else
     new_args = {...}
   end
   for _, arg in ipairs(new_args) do
     table.insert(args, arg)
   end
-  return args, env
+  return args, env, io_extra
 end
 
 function module.insert(...)

test/functional/ui/embed_spec.lua

@@ -1,3 +1,5 @@
+local uv = require'luv'
+
 local helpers = require('test.functional.helpers')(after_each)
 local Screen = require('test.functional.ui.screen')
 
@@ -98,3 +100,49 @@ end
 
 describe('--embed UI on startup (ext_linegrid=true)', function() test_embed(true) end)
 describe('--embed UI on startup (ext_linegrid=false)', function() test_embed(false) end)
+
+describe('--embed UI', function()
+  it('can pass stdin', function()
+    local pipe = assert(uv.pipe())
+
+    local writer = assert(uv.new_pipe(false))
+    writer:open(pipe.write)
+
+    clear {args_rm={'--headless'}, io_extra=pipe.read}
+
+    -- attach immediately after startup, for early UI
+    local screen = Screen.new(40, 8)
+    screen:attach {stdin_fd=3}
+    screen:set_default_attr_ids {
+      [1] = {bold = true, foreground = Screen.colors.Blue1};
+      [2] = {bold = true};
+    }
+
+    writer:write "hello nvim\nfrom external input\n"
+    writer:shutdown(function() writer:close() end)
+
+    screen:expect{grid=[[
+      ^hello nvim                              |
+      from external input                     |
+      {1:~                                       }|
+      {1:~                                       }|
+      {1:~                                       }|
+      {1:~                                       }|
+      {1:~                                       }|
+                                              |
+    ]]}
+
+    -- stdin (rpc input) still works
+    feed 'o'
+    screen:expect{grid=[[
+      hello nvim                              |
+      ^                                        |
+      from external input                     |
+      {1:~                                       }|
+      {1:~                                       }|
+      {1:~                                       }|
+      {1:~                                       }|
+      {2:-- INSERT --}                            |
+    ]]}
+  end)
+end)