test: skip noisy "terminal mode unavailable" logs #36794

Problem:
Every CI log has a lot of noise at the end, which makes it harder to
find relevant test failures:

    Running tests from test/functional/terminal/tui_spec.lua
    ...
    T5831 TUI bg color queries the terminal for background color:
    T5832 TUI bg color triggers OptionSet from automatic background processing:
    T5833 TUI bg color sends theme update notifications when background changes #31652:
    ...
    Running tests from test/functional/ui/output_spec.lua
    ...
    WRN 2025-12-02T03:36:47.304 ui/c/T5831.28003.0 tui_handle_term_mode:223: TUI: terminal mode 2026 unavailable, state 0
    WRN 2025-12-02T03:36:47.359 ui/c/T5832.28006.0 tui_handle_term_mode:223: TUI: terminal mode 2048 unavailable, state 0
    WRN 2025-12-02T03:36:47.414 ui/c/T5833.28009.0 tui_handle_term_mode:223: TUI: terminal mode 2048 unavailable, state 0

Solution:
- Skip logging in test-mode.
    - This can be reverted later, when these logs are changed to "INFO"
      level, per this TODO comment:
      ```
      // TODO(bfredl): This is really ILOG but we want it in all builds.
      // add to show_verbose_terminfo() without being too racy ????
      WLOG("TUI: terminal mode %d unavailable, state %d", mode, state);
      ```

cmake/RunTests.cmake

@@ -1,3 +1,4 @@
+set(ENV{NVIM_TEST} "1")
 # Set LC_ALL to meet expectations of some locale-sensitive tests.
 set(ENV{LC_ALL} "en_US.UTF-8")
 set(ENV{VIMRUNTIME} ${WORKING_DIR}/runtime)

runtime/doc/dev_test.txt

@@ -438,6 +438,8 @@ Number; !must be defined to function properly):
 - `TEST_TIMEOUT` (FU) (I): specifies maximum time, in seconds, before the test
   suite run is killed
 
+- `NVIM_TEST` (FU) (D): lets Nvim process detect that it is running in a test.
+
 - `NVIM_LUA_NOTRACK` (F) (D): disable reference counting of Lua objects
 
 - `NVIM_PRG` (F) (S): path to Nvim executable (default: `build/bin/nvim`).

src/nvim/tui/tui.c

@@ -41,6 +41,7 @@
 #include "nvim/ugrid.h"
 #include "nvim/ui_client.h"
 #include "nvim/ui_defs.h"
+#include "nvim/vim_defs.h"
 
 #ifdef MSWIN
 # include "nvim/os/os_win_console.h"
@@ -214,13 +215,20 @@ static void tui_set_term_mode(TUIData *tui, TermMode mode, bool set)
 void tui_handle_term_mode(TUIData *tui, TermMode mode, TermModeState state)
   FUNC_ATTR_NONNULL_ALL
 {
+  static TriState is_test = kNone;
+  if (is_test == kNone) {
+    // XXX: Skip some logs which are noisy in CI. #33599
+    is_test = os_env_exists("NVIM_TEST", false);
+  }
   bool is_set = false;
   switch (state) {
   case kTermModeNotRecognized:
   case kTermModePermanentlyReset:
     // TODO(bfredl): This is really ILOG but we want it in all builds.
     // add to show_verbose_terminfo() without being too racy ????
-    WLOG("TUI: terminal mode %d unavailable, state %d", mode, state);
+    if (is_test == kFalse) {
+      WLOG("TUI: terminal mode %d unavailable, state %d", mode, state);
+    }
     // If the mode is not recognized, or if the terminal emulator does not allow it to be changed,
     // then there is nothing to do
     break;
@@ -230,7 +238,9 @@ void tui_handle_term_mode(TUIData *tui, TermMode mode, TermModeState state)
     FALLTHROUGH;
   case kTermModeReset:
     // The terminal supports changing the given mode
-    WLOG("TUI: terminal mode %d detected, state %d", mode, state);
+    if (is_test == kFalse) {
+      WLOG("TUI: terminal mode %d detected, state %d", mode, state);
+    }
     switch (mode) {
     case kTermModeSynchronizedOutput:
       // Ref: https://gist.github.com/christianparpart/d8a62cc1ab659194337d73e399004036

test/functional/terminal/tui_spec.lua

@@ -3159,8 +3159,7 @@ describe('TUI FocusGained/FocusLost', function()
   end)
 end)
 
--- These tests require `tt` because --headless/--embed
--- does not initialize the TUI.
+-- These tests require `tt` because --headless/--embed does not initialize the TUI.
 describe("TUI 't_Co' (terminal colors)", function()
   local screen
 
@@ -3439,8 +3438,7 @@ describe("TUI 't_Co' (terminal colors)", function()
   end)
 end)
 
--- These tests require `tt` because --headless/--embed
--- does not initialize the TUI.
+-- These tests require `tt` because --headless/--embed does not initialize the TUI.
 describe("TUI 'term' option", function()
   local screen
 
@@ -3491,8 +3489,7 @@ describe("TUI 'term' option", function()
   end)
 end)
 
--- These tests require `tt` because --headless/--embed
--- does not initialize the TUI.
+-- These tests require `tt` because --headless/--embed does not initialize the TUI.
 describe('TUI', function()
   local screen
 

test/functional/testnvim.lua

@@ -610,21 +610,22 @@ function M._new_argv(...)
         assert(type(v) == 'string')
         env_opt[k] = v
       end
+      -- Set these from the environment unless the caller defined them.
       for _, k in ipairs({
-        'HOME',
         'ASAN_OPTIONS',
-        'TSAN_OPTIONS',
-        'MSAN_OPTIONS',
+        'GCOV_ERROR_FILE',
+        'HOME',
         'LD_LIBRARY_PATH',
-        'PATH',
+        'MSAN_OPTIONS',
+        'NVIM_TEST',
         'NVIM_LOG_FILE',
         'NVIM_RPLUGIN_MANIFEST',
-        'GCOV_ERROR_FILE',
-        'XDG_DATA_DIRS',
+        'PATH',
         'TMPDIR',
+        'TSAN_OPTIONS',
         'VIMRUNTIME',
+        'XDG_DATA_DIRS',
       }) do
-        -- Set these from the environment unless the caller defined them.
         if not env_opt[k] then
           env_opt[k] = os.getenv(k)
         end

test/functional/testterm.lua

@@ -200,9 +200,8 @@ function M.setup_child_nvim(args, opts)
   local argv = { nvim_prog, unpack(args or {}) }
 
   local env = opts.env or {}
-  if not env.VIMRUNTIME then
-    env.VIMRUNTIME = os.getenv('VIMRUNTIME')
-  end
+  env.VIMRUNTIME = env.VIMRUNTIME or os.getenv('VIMRUNTIME')
+  env.NVIM_TEST = env.NVIM_TEST or os.getenv('NVIM_TEST')
 
   return M.setup_screen(opts.extra_rows, argv, opts.cols, env)
 end