Add test runner option --log-test-environment (#25843)

Add test runner option --log-test-environment, which will introspect and
print detailed information about Emscripten tool setup: Emcc, Clang,
Binaryen, Node, Python and LLVM. This helps CI maintainers emit info to
test run logs of the active setup for reference.

`test/runner --log-test-environment <tests_to_run>` will then print a
following log info dump before starting the tests:

```

C:\emsdk\emscripten\main>test\runner --log-test-environment
======================== Test Setup ========================
Test time: Thursday, November 20, 2025 22:28:18 UTC
Python: "C:\emsdk\python\3.13.3_64bit\python.exe". Version: 3.13.3 (tags/v3.13.3:6280bb5, Apr  8 2025, 14:47:33) [MSC v.1943 64 bit (AMD64)]
Emscripten test runner path: "C:\emsdk\emscripten\main\test\runner.py"

Emscripten repository: "C:\emsdk\emscripten\main"
emscripten-version.txt: 4.0.21-git

Emscripten commit cce3a70
Author: Jukka Jylänki <[email protected]>
Date:   Fri Nov 21 00:26:51 2025 +0200

    Add test runner option --log-test-environment, which will introspect and print detailed information about Emscripten tool setup: Emcc, Clang, Binaryen, Node, Python and LLVM. This helps CI maintainers emit info to test run logs of the active setup for reference.

EM_CONFIG: "C:\emsdk\.emscripten"

import os
emsdk_path = os.path.dirname(os.getenv('EM_CONFIG')).replace('\\', '/')
LLVM_ROOT = emsdk_path + '/llvm/git/build_main_vs2022_64/Release/bin'
NODE_JS = emsdk_path + '/node/22.16.0_64bit/bin/node.exe'
EMSDK_CMAKE = emsdk_path + '/cmake/4.2.0-rc3_64bit/bin/cmake.exe'
PYTHON = emsdk_path + '/python/3.13.3_64bit/python.exe'
EMSCRIPTEN_ROOT = emsdk_path + '/emscripten/main'
BINARYEN_ROOT = emsdk_path + '/binaryen/main_vs2022_64bit_binaryen'
MINGW_ROOT = emsdk_path + '/mingw/7.1.0_64bit'
NINJA = emsdk_path + '/ninja/git-release_64bit/bin'
EMSDK_ACTIVATED_TEST_BROWSER = emsdk_path + '/firefox/78.15.0esr_64bit/firefox.exe'

NODE_JS: ['C:/emsdk/node/22.16.0_64bit/bin/node.exe']. Version: v22.16.0
BINARYEN_ROOT: C:/emsdk/binaryen/main_vs2022_64bit_binaryen
wasm-opt version: wasm-opt version 124 (version_124-122-g8a66d2a7d)
Binaryen git directory: "C:\emsdk\binaryen\main"

Binaryen commit 8a66d2a7d48a0014dce5e22a2fa8eee12eb09b7c
Author: Alon Zakai <[email protected]>
Date:   Thu Nov 6 11:53:49 2025 -0800

    GUFA: Represent imported functions as globals (#8025)

    The meaning of Global in PossibleContents changes from "an actual wasm
    Global" to "an immutable global wasm thing, either a Global or a Function."
    Imported wasm Functions are effectively immutable values in the global
    scope - not concrete, specifically-known functions - so this is more correct.

    In particular, two imported Globals (of compatible types) might or might not
    be the same, and likewise with imported Functions. And that is not the case
    for defined Functions - they are definitely different.

    This does not fix the issues related to imported function type handling -
    #7993 does that - but this refactoring makes it possible to properly
    optimize imported functions afterward.

    This does make the PossibleContents object grow from 32 to 40 bytes,
    which might be why this adds 3-4% overhead to GUFA, but I don't see a
    good way to avoid that, unfortunately. Keeping our ability to optimize
    imported functions might be worth that 3-4% (we recently saw a few digits
    improvement due to properly optimizing imported externs, for example,
    from #8005).

LLVM_ROOT: C:/emsdk/llvm/git/build_main_vs2022_64/Release/bin
LLVM git directory: "C:/emsdk/llvm/git\src"

LLVM commit d65be16ab6adf00af21e75d29049ae5de0f3a38a
Author: Ryan Cowan <[email protected]>
Date:   Mon Nov 17 15:55:40 2025 +0000

    [AArch64][GlobalISel] Add combine for build_vector(unmerge, unmerge, undef, undef) (#165539)

    This PR adds a new combine to the `post-legalizer-combiner` pass. The
    new combine checks for vectors being unmerged and subsequently padded
    with `G_IMPLICIT_DEF` values by building a new vector. If such a case is
    found, the vector being unmerged is instead just concatenated with a
    `G_IMPLICIT_DEF` that is as wide as the vector being unmerged.

    This removes unnecessary `mov` instructions in a few places.

Clang: "C:/emsdk/llvm/git/build_main_vs2022_64/Release/bin\clang.exe"
clang version 22.0.0git (https://github.com/llvm/llvm-project.git d65be16ab6adf00af21e75d29049ae5de0f3a38a)
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: C:\emsdk\llvm\git\build_main_vs2022_64\Release\bin

EMTEST_BROWSER: "C:\\emsdk\\firefox\\78.15.0esr_64bit\\firefox.exe" -new-instance -wait-for-browser
Firefox version: 78
Not detected as a Safari browser

EMSDK: "C:/emsdk"

Emsdk commit fe91d96cfd53f505a2ce561b01320124bff438a1
Author: Jukka Jylänki <[email protected]>
Date:   Mon Nov 17 18:41:28 2025 +0200

    Use exit_with_error

==================== End of Test Setup =====================
```

Author: juj

test/runner.py

@@ -19,13 +19,16 @@
 
 import argparse
 import atexit
+import datetime
 import fnmatch
 import glob
 import logging
 import math
 import operator
 import os
 import random
+import re
+import subprocess
 import sys
 import time
 import unittest
@@ -44,7 +47,7 @@
 from common import errlog
 from single_line_runner import SingleLineTestRunner
 
-from tools import colored_logger, config, shared, utils
+from tools import building, colored_logger, config, shared, utils
 
 logger = logging.getLogger("runner")
 
@@ -506,6 +509,7 @@ def parse_args():
                            'Useful when combined with --failfast')
   parser.add_argument('--force64', action='store_true')
   parser.add_argument('--crossplatform-only', action='store_true')
+  parser.add_argument('--log-test-environment', action='store_true', help='Prints out detailed information about the current environment. Useful for adding more info to CI test runs.')
   parser.add_argument('--force-browser-process-termination', action='store_true', help='If true, a fail-safe method is used to ensure that all browser processes are terminated before and after the test suite run. Note that this option will terminate all browser processes, not just those launched by the harness, so will result in loss of all open browsing sessions.')
   parser.add_argument('--repeat', type=int, default=1,
                       help='Repeat each test N times (default: 1).')
@@ -563,6 +567,95 @@ def cleanup_emscripten_temp():
         pass
 
 
+def print_repository_info(directory, repository_name):
+  current_commit = utils.run_process(['git', 'log', '--abbrev-commit', '-n1', '--pretty=oneline'], cwd=directory, stdout=subprocess.PIPE).stdout.strip()
+  print(f'\n{repository_name} {current_commit}\n')
+  local_changes = utils.run_process(['git', 'diff'], cwd=directory, stdout=subprocess.PIPE).stdout.strip()
+  if local_changes:
+    print(f'\n{local_changes}\n')
+
+
+def log_test_environment():
+  """Print detailed information about the current test environment. Useful for
+  logging test run configuration in a CI."""
+  print('======================== Test Setup ========================')
+  print(f'Test time: {datetime.datetime.now(datetime.timezone.utc).strftime("%A, %B %d, %Y %H:%M:%S %Z")}')
+  print(f'Python: "{sys.executable}". Version: {sys.version}')
+  print(f'Emscripten test runner path: "{os.path.realpath(__file__)}"')
+
+  if os.path.isdir(utils.path_from_root('.git')):
+    print(f'\nEmscripten repository: "{__rootpath__}"')
+
+  emscripten_version = utils.path_from_root('emscripten-version.txt')
+  if os.path.isfile(emscripten_version):
+    print(f'emscripten-version.txt: {utils.EMSCRIPTEN_VERSION}')
+
+  if os.path.isdir(os.path.join(__rootpath__, '.git')):
+    print_repository_info(__rootpath__, 'Emscripten')
+
+  print(f'EM_CONFIG: "{config.EM_CONFIG}"')
+  if os.path.isfile(config.EM_CONFIG):
+    print(f'\n{utils.read_file(config.EM_CONFIG).strip()}\n')
+
+  node_js_version = utils.run_process(config.NODE_JS + ['--version'], stdout=subprocess.PIPE).stdout.strip()
+  print(f'NODE_JS: {config.NODE_JS}. Version: {node_js_version}')
+
+  print(f'BINARYEN_ROOT: {config.BINARYEN_ROOT}')
+  wasm_opt_version = building.get_binaryen_version(building.get_binaryen_bin()).strip()
+  print(f'wasm-opt version: {wasm_opt_version}')
+
+  binaryen_git_dir = config.BINARYEN_ROOT
+  # Detect emsdk directory structure (build root vs source root)
+  if re.match(r'main_.*_64bit_binaryen', os.path.basename(binaryen_git_dir)):
+    binaryen_git_dir = os.path.realpath(os.path.join(binaryen_git_dir, '..', 'main'))
+  if os.path.isdir(os.path.join(binaryen_git_dir, '.git')):
+    print(f'Binaryen git directory: "{binaryen_git_dir}"')
+    print_repository_info(binaryen_git_dir, 'Binaryen')
+
+  print(f'LLVM_ROOT: {config.LLVM_ROOT}')
+
+  # Find LLVM git directory in emsdk aware fashion
+  def find_llvm_git_root(dir):
+    while True:
+      if os.path.isdir(os.path.join(dir, ".git")):
+        return dir
+      if os.path.isdir(os.path.join(dir, "src", ".git")):
+        return os.path.join(dir, "src")
+      if os.path.dirname(dir) == dir:
+        return None
+      dir = os.path.dirname(dir)
+
+  llvm_git_root = find_llvm_git_root(config.LLVM_ROOT)
+  if llvm_git_root:
+    print(f'LLVM git directory: "{llvm_git_root}"')
+    print_repository_info(llvm_git_root, 'LLVM')
+
+  clang_version = utils.run_process([shared.CLANG_CC, '--version'], stdout=subprocess.PIPE).stdout.strip()
+  print(f'Clang: "{shared.CLANG_CC}"\n{clang_version}\n')
+
+  print(f'EMTEST_BROWSER: {browser_common.EMTEST_BROWSER}')
+  if browser_common.is_firefox():
+    print(f'Firefox version: {browser_common.get_firefox_version()}')
+  else:
+    print('Not detected as a Firefox browser')
+  if browser_common.is_safari():
+    print(f'Safari version: {browser_common.get_safari_version()}')
+  else:
+    print('Not detected as a Safari browser')
+  if browser_common.is_chrome():
+    print('Browser is Chrome.')
+  else:
+    print('Not detected as a Chrome browser')
+
+  emsdk_dir = os.getenv('EMSDK')
+  print(f'\nEMSDK: "{emsdk_dir}"')
+  if emsdk_dir:
+    if os.path.isdir(os.path.join(emsdk_dir, '.git')):
+      print_repository_info(emsdk_dir, 'Emsdk')
+
+  print('==================== End of Test Setup =====================')
+
+
 def main():
   options = parse_args()
 
@@ -606,6 +699,9 @@ def set_env(name, option_value):
 
   browser_common.init(options.force_browser_process_termination)
 
+  if options.log_test_environment or os.getenv('CI'):
+    log_test_environment()
+
   def prepend_default(arg):
     if arg.startswith('test_'):
       return default_core_test_mode + '.' + arg

tools/building.py

@@ -1189,21 +1189,25 @@ def get_binaryen_feature_flags():
     return ['--detect-features']
 
 
-def check_binaryen(bindir):
+def get_binaryen_version(bindir):
   opt = os.path.join(bindir, utils.exe_suffix('wasm-opt'))
   if not os.path.exists(opt):
     exit_with_error('binaryen executable not found (%s). Please check your binaryen installation' % opt)
   try:
-    output = run_process([opt, '--version'], stdout=PIPE).stdout
+    return run_process([opt, '--version'], stdout=PIPE).stdout
   except subprocess.CalledProcessError:
     exit_with_error('error running binaryen executable (%s). Please check your binaryen installation' % opt)
+
+
+def check_binaryen(bindir):
+  output = get_binaryen_version(bindir)
   if output:
     output = output.splitlines()[0]
   try:
     version = output.split()[2]
     version = int(version)
   except (IndexError, ValueError):
-    exit_with_error('error parsing binaryen version (%s). Please check your binaryen installation (%s)' % (output, opt))
+    exit_with_error(f'error parsing binaryen version ({output}). Please check your binaryen installation')
 
   # Allow the expected version or the following one in order avoid needing to update both
   # emscripten and binaryen in lock step in emscripten-releases.