api: Support getting the number of a window/tabpage

In order to provide better compatibility with the classic bindings, the
API needs to provide the ability to query the number (really index) of
the window/tabpage.

This is needed for neovim/python-client#87, as discussed in
neovim/neovim#1898.

Signed-off-by: James McCoy <jamessan@jamessan.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/test/functional/api/window_spec.lua b/test/functional/api/window_spec.lua
index 2c43e4db2c..bf2bf55fb3 100644
--- a/test/functional/api/window_spec.lua
+++ b/test/functional/api/window_spec.lua
@@ -200,6 +200,30 @@ describe('window_* functions', function()
     end)
   end)
 
+  describe('get_number', function()
+    it('works', function()
+      local wins = nvim('list_wins')
+      eq(1, window('get_number', wins[1]))
+
+      nvim('command', 'split')
+      local win1, win2 = unpack(nvim('list_wins'))
+      eq(1, window('get_number', win1))
+      eq(2, window('get_number', win2))
+
+      nvim('command', 'wincmd J')
+      eq(2, window('get_number', win1))
+      eq(1, window('get_number', win2))
+
+      nvim('command', 'tabnew')
+      local win3 = nvim('list_wins')[3]
+      -- First tab page
+      eq(2, window('get_number', win1))
+      eq(1, window('get_number', win2))
+      -- Second tab page
+      eq(1, window('get_number', win3))
+    end)
+  end)
+
   describe('is_valid', function()
     it('works', function()
       nvim('command', 'split')