feat(api): nvim_get_commands returns desc #39623

Problem:
Can't get a command's description from nvim_get_commands when
cmd is string.

Solution:
Returns "desc" field in nvim_get_commands.
`definition` is now empty when cmd is function type.

test/functional/api/command_spec.lua

@@ -23,6 +23,7 @@ describe('nvim_get_commands', function()
     complete_arg = NIL,
     count = NIL,
     definition = 'echo "Hello World"',
+    desc = '',
     name = 'Hello',
     nargs = '1',
     range = NIL,
@@ -38,6 +39,7 @@ describe('nvim_get_commands', function()
     complete_arg = NIL,
     count = NIL,
     definition = 'pwd',
+    desc = '',
     name = 'Pwd',
     nargs = '?',
     range = NIL,
@@ -54,6 +56,15 @@ describe('nvim_get_commands', function()
   it('validation', function()
     eq('builtin=true not implemented', pcall_err(api.nvim_get_commands, { builtin = true }))
     eq("Invalid key: 'foo'", pcall_err(api.nvim_get_commands, { foo = 'blah' }))
+    matches(
+      "Invalid 'desc'",
+      pcall_err(
+        exec_lua,
+        [[
+        vim.api.nvim_create_user_command('Bad', 'echo "hi"', { desc = 123 })
+      ]]
+      )
+    )
   end)
 
   it('gets global user-defined commands', function()
@@ -92,6 +103,7 @@ describe('nvim_get_commands', function()
       complete_arg = NIL,
       count = '10',
       definition = 'pwd <args>',
+      desc = '',
       name = 'TestCmd',
       nargs = '1',
       range = '10',
@@ -107,6 +119,7 @@ describe('nvim_get_commands', function()
       complete_arg = 'ListUsers',
       count = NIL,
       definition = '!finger <args>',
+      desc = '',
       name = 'Finger',
       nargs = '+',
       range = NIL,
@@ -122,6 +135,7 @@ describe('nvim_get_commands', function()
       complete_arg = NIL,
       count = NIL,
       definition = 'call \128\253R2_foo(<q-args>)',
+      desc = '',
       name = 'Cmd2',
       nargs = '*',
       range = NIL,
@@ -137,6 +151,7 @@ describe('nvim_get_commands', function()
       complete_arg = NIL,
       count = NIL,
       definition = 'call \128\253R3_ohyeah()',
+      desc = '',
       name = 'Cmd3',
       nargs = '0',
       range = NIL,
@@ -152,6 +167,7 @@ describe('nvim_get_commands', function()
       complete_arg = NIL,
       count = NIL,
       definition = 'call \128\253R4_just_great()',
+      desc = '',
       name = 'Cmd4',
       nargs = '0',
       range = NIL,
@@ -167,6 +183,7 @@ describe('nvim_get_commands', function()
       complete_arg = 's:cpt',
       count = NIL,
       definition = '',
+      desc = '',
       name = 'PreviewCmd',
       nargs = '1',
       range = NIL,
@@ -184,6 +201,7 @@ describe('nvim_get_commands', function()
       complete_arg = NIL,
       count = NIL,
       definition = '',
+      desc = 'Preview Lua Cmd',
       name = 'PreviewLuaCmd',
       nargs = '1',
       range = NIL,
@@ -191,6 +209,22 @@ describe('nvim_get_commands', function()
       keepscript = false,
       script_id = -8, -- Lua
     }
+    local withDesc = {
+      addr = vim.NIL,
+      bang = false,
+      bar = false,
+      complete = vim.NIL,
+      complete_arg = vim.NIL,
+      count = vim.NIL,
+      definition = 'echo "hi"',
+      desc = 'Says hi',
+      keepscript = false,
+      name = 'WithDesc',
+      nargs = '0',
+      range = vim.NIL,
+      register = false,
+      script_id = -8,
+    }
 
     source([[
       let s:foo = 1
@@ -230,8 +264,14 @@ describe('nvim_get_commands', function()
           nargs = 1,
           complete = function() return 3 end,
           preview = function() return 4 end,
+          desc = 'Preview Lua Cmd'
         }
       )
+      vim.api.nvim_create_user_command(
+        'WithDesc',
+        'echo "hi"',
+        { desc = 'Says hi' }
+      )
       EOF
     ]])
     -- TODO(justinmk): Order is stable but undefined. Sort before return?
@@ -244,6 +284,7 @@ describe('nvim_get_commands', function()
       TestCmd = cmd0,
       PreviewCmd = previewCmd,
       PreviewLuaCmd = previewLuaCmd,
+      WithDesc = withDesc,
     }, commands)
   end)