functests: Test for error conditions

During testing found the following bugs:

1. msgpack-gen.lua script is completely unprepared for Float values either in 
   return type or in arguments. Specifically:

   1. At the time of writing relevant code FLOAT_OBJ did not exist as well as 
      FLOATING_OBJ, but it would be used by msgpack-gen.lua should return type 
      be Float. I added FLOATING_OBJ macros later because did not know that 
      msgpack-gen.lua uses these _OBJ macros, otherwise it would be FLOAT_OBJ.
   2. msgpack-gen.lua should use .data.floating in place of .data.float. But it 
      did not expect that .data subattribute may have name different from 
      lowercased type name.

2. vim_replace_termcodes returned its argument as-is if it receives an empty 
   string (as well as _vim_id*() functions did). But if something in returned 
   argument lives in an allocated memory such action will cause double free: 
   once when freeing arguments, then when freeing return value. It did not cause 
   problems yet because msgpack bindings return empty string as {NULL, 0} and 
   nothing was actually allocated.
3. New code in msgpack-gen.lua popped arguments in reversed order, making lua 
   bindings’ signatures be different from API ones.

2 files changed, 57 insertions, 5 deletions

diff --git a/test/functional/api/vim_spec.lua b/test/functional/api/vim_spec.lua
index 3348368a36..24ed0afe67 100644
--- a/test/functional/api/vim_spec.lua
+++ b/test/functional/api/vim_spec.lua
@@ -219,6 +219,17 @@ describe('api', function()
       eq('\128\253\44', helpers.nvim('replace_termcodes',
                                      '<LeftMouse>', true, true, true))
     end)
+
+    it('does not crash when transforming an empty string', function()
+      -- Actually does not test anything, because current code will use NULL for
+      -- an empty string.
+      --
+      -- Problem here is that if String argument has .data in allocated memory
+      -- then `return str` in vim_replace_termcodes body will make Neovim free
+      -- `str.data` twice: once when freeing arguments, then when freeing return
+      -- value.
+      eq('', meths.replace_termcodes('', true, true, true))
+    end)
   end)
 
   describe('nvim_feedkeys', function()
diff --git a/test/functional/lua_spec.lua b/test/functional/lua_spec.lua
index 082efe4c0e..8ca47718aa 100644
--- a/test/functional/lua_spec.lua
+++ b/test/functional/lua_spec.lua
@@ -276,12 +276,53 @@ describe('luaeval() function', function()
   end)
 
   it('errors out correctly when working with API', function()
-    eq(0, exc_exec([[call luaeval("vim.api.id")]]))
+    -- Conversion errors
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Cannot convert given lua type',
+       exc_exec([[call luaeval("vim.api._vim_id(vim.api._vim_id)")]]))
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Cannot convert given lua table',
+       exc_exec([[call luaeval("vim.api._vim_id({1, foo=42})")]]))
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Cannot convert given lua type',
+       exc_exec([[call luaeval("vim.api._vim_id({42, vim.api._vim_id})")]]))
+    -- Errors in number of arguments
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Expected 1 argument',
+       exc_exec([[call luaeval("vim.api._vim_id()")]]))
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Expected 1 argument',
+       exc_exec([[call luaeval("vim.api._vim_id(1, 2)")]]))
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Expected 2 arguments',
+       exc_exec([[call luaeval("vim.api.vim_set_var(1, 2, 3)")]]))
+    -- Error in argument types
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Expected lua string',
+       exc_exec([[call luaeval("vim.api.vim_set_var(1, 2)")]]))
+
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Expected lua number',
+       exc_exec([[call luaeval("vim.api.buffer_get_line(0, 'test')")]]))
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Number is not integral',
+       exc_exec([[call luaeval("vim.api.buffer_get_line(0, 1.5)")]]))
+
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Expected lua table',
+       exc_exec([[call luaeval("vim.api._vim_id_float('test')")]]))
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Unexpected type',
+       exc_exec([[call luaeval("vim.api._vim_id_float({[vim.type_idx]=vim.types.dictionary})")]]))
+
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Expected lua table',
+       exc_exec([[call luaeval("vim.api._vim_id_array(1)")]]))
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Unexpected type',
+       exc_exec([[call luaeval("vim.api._vim_id_array({[vim.type_idx]=vim.types.dictionary})")]]))
+
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Expected lua table',
+       exc_exec([[call luaeval("vim.api._vim_id_dictionary(1)")]]))
+    eq('Vim(call):E5108: Error while calling lua chunk for luaeval(): Unexpected type',
+       exc_exec([[call luaeval("vim.api._vim_id_dictionary({[vim.type_idx]=vim.types.array})")]]))
+    -- TODO: check for errors with Tabpage argument
+    -- TODO: check for errors with Window argument
+    -- TODO: check for errors with Buffer argument
+  end)
+
+  it('accepts any value as API Boolean', function()
+    eq('', funcs.luaeval('vim.api.vim_replace_termcodes("", vim, false, nil)'))
+    eq('', funcs.luaeval('vim.api.vim_replace_termcodes("", 0, 1.5, "test")'))
+    eq('', funcs.luaeval('vim.api.vim_replace_termcodes("", true, {}, {[vim.type_idx]=vim.types.array})'))
   end)
 
   -- TODO: check buffer/window/etc.
-  -- TODO: check what happens when it errors out on second list item
-  -- TODO: check what happens if API function receives wrong number of
-  -- arguments.
-  -- TODO: check what happens if API function receives wrong argument types.
 end)