2 files changed, 16 insertions, 2 deletions
diff --git a/test/functional/fixtures/fake-lsp-server.lua b/test/functional/fixtures/fake-lsp-server.lua
index cac590fd14..dca7f35923 100644
--- a/test/functional/fixtures/fake-lsp-server.lua
+++ b/test/functional/fixtures/fake-lsp-server.lua
@@ -1,6 +1,16 @@
 local protocol = require 'vim.lsp.protocol'
 
 
+-- Logs to $NVIM_LOG_FILE.
+--
+-- TODO(justinmk): remove after https://github.com/neovim/neovim/pull/7062
+local function log(loglevel, area, msg)
+  vim.fn.writefile(
+    {string.format('%s %s: %s', loglevel, area, msg)},
+    vim.env.NVIM_LOG_FILE,
+    'a')
+end
+
 local function message_parts(sep, ...)
   local parts = {}
   for i = 1, select("#", ...) do
@@ -422,7 +432,7 @@ local kill_timer = vim.loop.new_timer()
 kill_timer:start(_G.TIMEOUT or 1e3, 0, function()
   kill_timer:stop()
   kill_timer:close()
-  -- TODO: log('TIMEOUT')
+  log('ERROR', 'LSP', 'TIMEOUT')
   io.stderr:write("TIMEOUT")
   os.exit(100)
 end)
@@ -433,7 +443,7 @@ local status, err = pcall(assert(tests[test_name], "Test not found"))
 kill_timer:stop()
 kill_timer:close()
 if not status then
-  -- TODO: log(err)
+  log('ERROR', 'LSP', tostring(err))
   io.stderr:write(err)
   os.exit(101)
 end
diff --git a/test/functional/plugin/lsp_spec.lua b/test/functional/plugin/lsp_spec.lua
index b2d00a400a..03e516d6f6 100644
--- a/test/functional/plugin/lsp_spec.lua
+++ b/test/functional/plugin/lsp_spec.lua
@@ -1,11 +1,13 @@
 local helpers = require('test.functional.helpers')(after_each)
 
+local assert_log = helpers.assert_log
 local clear = helpers.clear
 local buf_lines = helpers.buf_lines
 local dedent = helpers.dedent
 local exec_lua = helpers.exec_lua
 local eq = helpers.eq
 local eq_dumplog = helpers.eq_dumplog
+local pesc = helpers.pesc
 local insert = helpers.insert
 local retry = helpers.retry
 local NIL = helpers.NIL
@@ -229,6 +231,8 @@ describe('LSP', function()
         on_exit = function(code, signal)
           eq_dumplog(fake_lsp_logfile, 101, code, "exit code")  -- See fake-lsp-server.lua
           eq_dumplog(fake_lsp_logfile, 0, signal, "exit signal")
+          assert_log(pesc([[assert_eq failed: left == "\"shutdown\"", right == "\"test\""]]),
+            fake_lsp_logfile)
         end;
         on_callback = function(...)
           eq(table.remove(expected_callbacks), {...}, "expected callback")