patch 8.2.3288: cannot easily access namespace dictionaries from Lua

Problem:    Cannot easily access namespace dictionaries from Lua.
Solution:   Add vim.g, vim.b, etc. (Yegappan Lakshmanan, closes #8693,
            from NeoVim)
diff --git a/src/testdir/test_lua.vim b/src/testdir/test_lua.vim
index c30f959..953e8a9 100644
--- a/src/testdir/test_lua.vim
+++ b/src/testdir/test_lua.vim
@@ -916,4 +916,246 @@
   call assert_equal('ABCDE', s)
 endfunc
 
+" Test for adding, accessing and removing global variables using the vim.g
+" Lua table
+func Test_lua_global_var_table()
+  " Access global variables with different types of values
+  let g:Var1 = 10
+  let g:Var2 = 'Hello'
+  let g:Var3 = ['a', 'b']
+  let g:Var4 = #{x: 'edit', y: 'run'}
+  let g:Var5 = function('min')
+  call assert_equal(10, luaeval('vim.g.Var1'))
+  call assert_equal('Hello', luaeval('vim.g.Var2'))
+  call assert_equal(['a', 'b'], luaeval('vim.g.Var3'))
+  call assert_equal(#{x: 'edit', y: 'run'}, luaeval('vim.g.Var4'))
+  call assert_equal(2, luaeval('vim.g.Var5')([5, 9, 2]))
+
+  " Access list of dictionaries and dictionary of lists
+  let g:Var1 = [#{a: 10}, #{b: 20}]
+  let g:Var2 = #{p: [5, 6], q: [1.1, 2.2]}
+  call assert_equal([#{a: 10}, #{b: 20}], luaeval('vim.g.Var1'))
+  call assert_equal(#{p: [5, 6], q: [1.1, 2.2]}, luaeval('vim.g.Var2'))
+
+  " Create new global variables with different types of values
+  unlet g:Var1 g:Var2 g:Var3 g:Var4 g:Var5
+  lua << trim END
+    vim.g.Var1 = 34
+    vim.g.Var2 = 'World'
+    vim.g.Var3 = vim.list({'#', '$'})
+    vim.g.Var4 = vim.dict({model='honda', year=2020})
+    vim.g.Var5 = vim.funcref('max')
+  END
+  call assert_equal(34, g:Var1)
+  call assert_equal('World', g:Var2)
+  call assert_equal(['#', '$'], g:Var3)
+  call assert_equal(#{model: 'honda', year: 2020}, g:Var4)
+  call assert_equal(10, g:Var5([5, 10, 9]))
+
+  " Create list of dictionaries and dictionary of lists
+  unlet g:Var1 g:Var2
+  lua << trim END
+    vim.g.Var1 = vim.list({vim.dict({a=10}), vim.dict({b=20})})
+    vim.g.Var2 = vim.dict({p=vim.list({5, 6}), q=vim.list({1.1, 2.2})})
+  END
+  call assert_equal([#{a: 10}, #{b: 20}], luaeval('vim.g.Var1'))
+  call assert_equal(#{p: [5, 6], q: [1.1, 2.2]}, luaeval('vim.g.Var2'))
+
+  " Modify a global variable with a list value or a dictionary value
+  let g:Var1 = [10, 20]
+  let g:Var2 = #{one: 'mercury', two: 'mars'}
+  lua << trim END
+    vim.g.Var1[2] = Nil
+    vim.g.Var1[3] = 15
+    vim.g.Var2['two'] = Nil
+    vim.g.Var2['three'] = 'earth'
+  END
+  call assert_equal([10, 15], g:Var1)
+  call assert_equal(#{one: 'mercury', three: 'earth'}, g:Var2)
+
+  " Remove global variables with different types of values
+  let g:Var1 = 10
+  let g:Var2 = 'Hello'
+  let g:Var3 = ['a', 'b']
+  let g:Var4 = #{x: 'edit', y: 'run'}
+  let g:Var5 = function('min')
+  lua << trim END
+    vim.g.Var1 = Nil
+    vim.g.Var2 = Nil
+    vim.g.Var3 = Nil
+    vim.g.Var4 = Nil
+    vim.g.Var5 = Nil
+  END
+  call assert_false(exists('g:Var1'))
+  call assert_false(exists('g:Var2'))
+  call assert_false(exists('g:Var3'))
+  call assert_false(exists('g:Var4'))
+  call assert_false(exists('g:Var5'))
+
+  " Try to modify and remove a locked global variable
+  let g:Var1 = 10
+  lockvar g:Var1
+  call assert_fails('lua vim.g.Var1 = 20', 'variable is locked')
+  call assert_fails('lua vim.g.Var1 = Nil', 'variable is locked')
+  unlockvar g:Var1
+  let g:Var2 = [7, 14]
+  lockvar 0 g:Var2
+  lua vim.g.Var2[2] = Nil
+  lua vim.g.Var2[3] = 21
+  call assert_fails('lua vim.g.Var2 = Nil', 'variable is locked')
+  call assert_equal([7, 21], g:Var2)
+  lockvar 1 g:Var2
+  call assert_fails('lua vim.g.Var2[2] = Nil', 'list is locked')
+  call assert_fails('lua vim.g.Var2[3] = 21', 'list is locked')
+  unlockvar g:Var2
+
+  " Attempt to access a non-existing global variable
+  call assert_equal(v:null, luaeval('vim.g.NonExistingVar'))
+  lua vim.g.NonExisting = Nil
+
+  unlet! g:Var1 g:Var2 g:Var3 g:Var4 g:Var5
+endfunc
+
+" Test for accessing and modifying predefined vim variables using the vim.v
+" Lua table
+func Test_lua_predefined_var_table()
+  call assert_equal(v:progpath, luaeval('vim.v.progpath'))
+  let v:errmsg = 'SomeError'
+  call assert_equal('SomeError', luaeval('vim.v.errmsg'))
+  lua vim.v.errmsg = 'OtherError'
+  call assert_equal('OtherError', v:errmsg)
+  call assert_fails('lua vim.v.errmsg = Nil', 'variable is fixed')
+  let v:oldfiles = ['one', 'two']
+  call assert_equal(['one', 'two'], luaeval('vim.v.oldfiles'))
+  lua vim.v.oldfiles = vim.list({})
+  call assert_equal([], v:oldfiles)
+  call assert_equal(v:null, luaeval('vim.v.null'))
+  call assert_fails('lua vim.v.argv[1] = Nil', 'list is locked')
+  call assert_fails('lua vim.v.newvar = 1', 'Dictionary is locked')
+endfunc
+
+" Test for adding, accessing and modifying window-local variables using the
+" vim.w Lua table
+func Test_lua_window_var_table()
+  " Access window variables with different types of values
+  new
+  let w:wvar1 = 10
+  let w:wvar2 = 'edit'
+  let w:wvar3 = 3.14
+  let w:wvar4 = 0zdeadbeef
+  let w:wvar5 = ['a', 'b']
+  let w:wvar6 = #{action: 'run'}
+  call assert_equal(10, luaeval('vim.w.wvar1'))
+  call assert_equal('edit', luaeval('vim.w.wvar2'))
+  call assert_equal(3.14, luaeval('vim.w.wvar3'))
+  call assert_equal(0zdeadbeef, luaeval('vim.w.wvar4'))
+  call assert_equal(['a', 'b'], luaeval('vim.w.wvar5'))
+  call assert_equal(#{action: 'run'}, luaeval('vim.w.wvar6'))
+  call assert_equal(v:null, luaeval('vim.w.NonExisting'))
+
+  " modify a window variable
+  lua vim.w.wvar2 = 'paste'
+  call assert_equal('paste', w:wvar2)
+
+  " change the type stored in a variable
+  let w:wvar2 = [1, 2]
+  lua vim.w.wvar2 = vim.dict({a=10, b=20})
+  call assert_equal(#{a: 10, b: 20}, w:wvar2)
+
+  " create a new window variable
+  lua vim.w.wvar7 = vim.dict({a=vim.list({1, 2}), b=20})
+  call assert_equal(#{a: [1, 2], b: 20}, w:wvar7)
+
+  " delete a window variable
+  lua vim.w.wvar2 = Nil
+  call assert_false(exists('w:wvar2'))
+
+  new
+  call assert_equal(v:null, luaeval('vim.w.wvar1'))
+  call assert_equal(v:null, luaeval('vim.w.wvar2'))
+  %bw!
+endfunc
+
+" Test for adding, accessing and modifying buffer-local variables using the
+" vim.b Lua table
+func Test_lua_buffer_var_table()
+  " Access buffer variables with different types of values
+  let b:bvar1 = 10
+  let b:bvar2 = 'edit'
+  let b:bvar3 = 3.14
+  let b:bvar4 = 0zdeadbeef
+  let b:bvar5 = ['a', 'b']
+  let b:bvar6 = #{action: 'run'}
+  call assert_equal(10, luaeval('vim.b.bvar1'))
+  call assert_equal('edit', luaeval('vim.b.bvar2'))
+  call assert_equal(3.14, luaeval('vim.b.bvar3'))
+  call assert_equal(0zdeadbeef, luaeval('vim.b.bvar4'))
+  call assert_equal(['a', 'b'], luaeval('vim.b.bvar5'))
+  call assert_equal(#{action: 'run'}, luaeval('vim.b.bvar6'))
+  call assert_equal(v:null, luaeval('vim.b.NonExisting'))
+
+  " modify a buffer variable
+  lua vim.b.bvar2 = 'paste'
+  call assert_equal('paste', b:bvar2)
+
+  " change the type stored in a variable
+  let b:bvar2 = [1, 2]
+  lua vim.b.bvar2 = vim.dict({a=10, b=20})
+  call assert_equal(#{a: 10, b: 20}, b:bvar2)
+
+  " create a new buffer variable
+  lua vim.b.bvar7 = vim.dict({a=vim.list({1, 2}), b=20})
+  call assert_equal(#{a: [1, 2], b: 20}, b:bvar7)
+
+  " delete a buffer variable
+  lua vim.b.bvar2 = Nil
+  call assert_false(exists('b:bvar2'))
+
+  new
+  call assert_equal(v:null, luaeval('vim.b.bvar1'))
+  call assert_equal(v:null, luaeval('vim.b.bvar2'))
+  %bw!
+endfunc
+
+" Test for adding, accessing and modifying tabpage-local variables using the
+" vim.t Lua table
+func Test_lua_tabpage_var_table()
+  " Access tabpage variables with different types of values
+  let t:tvar1 = 10
+  let t:tvar2 = 'edit'
+  let t:tvar3 = 3.14
+  let t:tvar4 = 0zdeadbeef
+  let t:tvar5 = ['a', 'b']
+  let t:tvar6 = #{action: 'run'}
+  call assert_equal(10, luaeval('vim.t.tvar1'))
+  call assert_equal('edit', luaeval('vim.t.tvar2'))
+  call assert_equal(3.14, luaeval('vim.t.tvar3'))
+  call assert_equal(0zdeadbeef, luaeval('vim.t.tvar4'))
+  call assert_equal(['a', 'b'], luaeval('vim.t.tvar5'))
+  call assert_equal(#{action: 'run'}, luaeval('vim.t.tvar6'))
+  call assert_equal(v:null, luaeval('vim.t.NonExisting'))
+
+  " modify a tabpage variable
+  lua vim.t.tvar2 = 'paste'
+  call assert_equal('paste', t:tvar2)
+
+  " change the type stored in a variable
+  let t:tvar2 = [1, 2]
+  lua vim.t.tvar2 = vim.dict({a=10, b=20})
+  call assert_equal(#{a: 10, b: 20}, t:tvar2)
+
+  " create a new tabpage variable
+  lua vim.t.tvar7 = vim.dict({a=vim.list({1, 2}), b=20})
+  call assert_equal(#{a: [1, 2], b: 20}, t:tvar7)
+
+  " delete a tabpage variable
+  lua vim.t.tvar2 = Nil
+  call assert_false(exists('t:tvar2'))
+
+  tabnew
+  call assert_equal(v:null, luaeval('vim.t.tvar1'))
+  call assert_equal(v:null, luaeval('vim.t.tvar2'))
+  %bw!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab