startup: wait for embedder before executing startup commands and files

Give embeders a chance to set up nvim, by processing a request before
startup. This allows an external UI to show messages and prompts from
--cmd and buffer loading (e.g. swap files)

1 files changed, 71 insertions, 0 deletions

diff --git a/test/functional/ui/embed_spec.lua b/test/functional/ui/embed_spec.lua
new file mode 100644
index 0000000000..7d41567fda
--- /dev/null
+++ b/test/functional/ui/embed_spec.lua
@@ -0,0 +1,71 @@
+local helpers = require('test.functional.helpers')(after_each)
+local Screen = require('test.functional.ui.screen')
+
+local feed = helpers.feed
+local spawn, set_session = helpers.spawn, helpers.set_session
+local nvim_prog, nvim_set = helpers.nvim_prog, helpers.nvim_set
+local merge_args, prepend_argv = helpers.merge_args, helpers.prepend_argv
+
+describe('--embed UI on startup', function()
+  local session, screen
+  local function startup(...)
+    local nvim_argv = {nvim_prog, '-u', 'NONE', '-i', 'NONE',
+                       '--cmd', nvim_set, '--embed'}
+    nvim_argv = merge_args(prepend_argv, nvim_argv, {...})
+    session = spawn(nvim_argv)
+    set_session(session)
+
+    -- attach immediately after startup, for early UI
+    screen = Screen.new(60, 8)
+    screen:attach()
+    screen:set_default_attr_ids({
+      [1] = {foreground = Screen.colors.Grey100, background = Screen.colors.Red},
+      [2] = {bold = true, foreground = Screen.colors.SeaGreen4},
+      [3] = {bold = true, foreground = Screen.colors.Blue1},
+    })
+  end
+
+  after_each(function()
+    session:close()
+  end)
+
+  it('can display errors', function()
+    startup('--cmd', 'echoerr invalid+')
+    screen:expect([[
+                                                                  |
+                                                                  |
+                                                                  |
+                                                                  |
+      Error detected while processing pre-vimrc command line:     |
+      E121: Undefined variable: invalid                           |
+      E15: Invalid expression: invalid+                           |
+      Press ENTER or type command to continue^                     |
+    ]])
+
+    feed('<cr>')
+    screen:expect([[
+      ^                                                            |
+      {3:~                                                           }|
+      {3:~                                                           }|
+      {3:~                                                           }|
+      {3:~                                                           }|
+      {3:~                                                           }|
+      {3:~                                                           }|
+                                                                  |
+    ]])
+  end)
+
+  it("doesn't erase output when setting colors", function()
+    startup('--cmd', 'echoerr "foo"', '--cmd', 'color default', '--cmd', 'echoerr "bar"')
+    screen:expect([[
+                                                                  |
+                                                                  |
+                                                                  |
+                                                                  |
+      Error detected while processing pre-vimrc command line:     |
+      foo                                                         |
+      {1:bar}                                                         |
+      {2:Press ENTER or type command to continue}^                     |
+    ]])
+  end)
+end)