2 files changed, 101 insertions, 3 deletions

diff --git a/runtime/lua/vim/lsp/util.lua b/runtime/lua/vim/lsp/util.lua
index e77b9f199c..6a1e799489 100644
--- a/runtime/lua/vim/lsp/util.lua
+++ b/runtime/lua/vim/lsp/util.lua
@@ -160,7 +160,7 @@ function M.apply_text_document_edit(text_document_edit)
   local text_document = text_document_edit.textDocument
   local bufnr = vim.uri_to_bufnr(text_document.uri)
   -- `VersionedTextDocumentIdentifier`s version may be nil https://microsoft.github.io/language-server-protocol/specification#versionedTextDocumentIdentifier
-  if text_document.version ~= nil and M.buf_versions[bufnr] > text_document.version then
+  if text_document.version ~= vim.NIL and M.buf_versions[bufnr] > text_document.version then
     print("Buffer ", text_document.uri, " newer than edits.")
     return
   end
diff --git a/test/functional/plugin/lsp_spec.lua b/test/functional/plugin/lsp_spec.lua
index 1a0063b43e..79f6ef9dd2 100644
--- a/test/functional/plugin/lsp_spec.lua
+++ b/test/functional/plugin/lsp_spec.lua
@@ -770,13 +770,14 @@ describe('LSP', function()
       exec_lua([[require'vim.lsp'; return vim.fn.getcompletion('Lsp', 'highlight')]]))
   end)
 
-  describe('apply_edits', function()
+  describe('apply_text_edits', function()
     before_each(function()
       insert(dedent([[
         First line of text
         Second line of text
         Third line of text
-        Fourth line of text]]))
+        Fourth line of text
+        å å ɧ 汉语 ↥ 🤦 🦄]]))
     end)
     it('applies apply simple edits', function()
       local edits = {
@@ -790,6 +791,7 @@ describe('LSP', function()
         '2econd line of text';
         '3ird line of text';
         'Fourth line of text';
+        'å å ɧ 汉语 ↥ 🤦 🦄';
       }, buf_lines(1))
     end)
     it('applies complex edits', function()
@@ -813,8 +815,104 @@ describe('LSP', function()
         'The next line of text';
         'another line of text';
         'before this!';
+        'å å ɧ 汉语 ↥ 🤦 🦄';
       }, buf_lines(1))
     end)
+    pending('applies non-ASCII characters edits', function()
+      -- FIXME: We don't handle non-ASCII characters well in UTF-16
+      local edits = {
+        make_edit(4, 0, 4, 14, {"a a h"});
+      }
+      exec_lua('vim.lsp.util.apply_text_edits(...)', edits, 1)
+      eq({
+        'First line of text';
+        'Second line of text';
+        'Third line of text';
+        'Fourth line of text';
+        'a a h';
+      }, buf_lines(1))
+    end)
+  end)
+
+  describe('apply_text_document_edit', function()
+    local target_bufnr
+    before_each(function()
+      target_bufnr = exec_lua [[
+        local bufnr = vim.fn.bufadd("fake/uri")
+        local lines = {"1st line of text", "2nd line of text"}
+        vim.api.nvim_buf_set_lines(bufnr, 0, 1, false, lines)
+        return bufnr
+      ]]
+    end)
+    it('correctly goes ahead with the edit if all is normal', function()
+      local text_document_edit = {
+        edits = {
+          make_edit(0, 0, 0, 3, "First")
+        },
+        textDocument = {
+          uri = "file://fake/uri";
+          version = 5
+        }
+      }
+      exec_lua([[
+        local args = {...}
+        local target_bufnr = args[2]
+        vim.lsp.util.buf_versions[target_bufnr] = 4
+        vim.lsp.util.apply_text_document_edit(...)
+      ]], text_document_edit, target_bufnr)
+      eq({
+        'First line of text';
+        '2nd line of text';
+      }, buf_lines(target_bufnr))
+    end)
+    it('correctly goes ahead with the edit if the version is vim.NIL', function()
+      -- we get vim.NIL when we decode json null value.
+      local json = exec_lua[[
+        return vim.fn.json_decode("{ \"a\": 1, \"b\": null }")
+      ]]
+      eq(json.b, exec_lua("return vim.NIL"))
+
+      local text_document_edit = {
+        edits = {
+          make_edit(0, 0, 0, 3, "First")
+        },
+        textDocument = {
+          uri = "file://fake/uri";
+          version = exec_lua("return vim.NIL")
+        }
+      }
+      exec_lua([[
+        local args = {...}
+        local target_bufnr = args[2]
+        vim.lsp.util.buf_versions[target_bufnr] = vim.NIL
+        vim.lsp.util.apply_text_document_edit(...)
+      ]], text_document_edit, target_bufnr)
+      eq({
+        'First line of text';
+        '2nd line of text';
+      }, buf_lines(target_bufnr))
+    end)
+    it('skips the edit if the version of the edit is behind the local buffer ', function()
+      local text_document_edit = {
+        edits = {
+          make_edit(0, 0, 0, 3, "First")
+        },
+        textDocument = {
+          uri = "file://fake/uri";
+          version = 1
+        }
+      }
+      exec_lua([[
+        local args = {...}
+        local target_bufnr = args[2]
+        vim.lsp.util.buf_versions[target_bufnr] = 2
+        vim.lsp.util.apply_text_document_edit(...)
+      ]], text_document_edit, target_bufnr)
+      eq({
+        '1st line of text';
+        '2nd line of text';
+      }, buf_lines(target_bufnr))
+    end)
   end)
 
   describe('completion_list_to_complete_items', function()