Be more precise about which tests are disabled on macOS due to timestamp issue (#342)

test.py

@@ -68,6 +68,12 @@ print('building proper system libraries')
 
 
 def test_lib_building(emcc, use_asmjs_optimizer):
+  # TODO(sbc): Re-enable this part of the test once this upstream emscripten fix
+  # makes it into a release:
+  # https://github.com/emscripten-core/emscripten/pull/9347
+  if MACOS:
+    return
+
   def test_build(args, expected=None, unexpected=None):
     checked_call_with_output(emcc + ' hello_world.cpp' + args,
                              expected=expected,
@@ -102,6 +108,7 @@ def run_emsdk(cmd):
 
 
 WINDOWS = sys.platform.startswith('win')
+MACOS = sys.platform == 'darwin'
 
 upstream_emcc = os.path.join('upstream', 'emscripten', 'emcc')
 fastcomp_emcc = os.path.join('fastcomp', 'emscripten', 'emcc')
@@ -121,6 +128,7 @@ run_emsdk('update-tags')
 print('test latest-releases-upstream')
 run_emsdk('install latest-upstream')
 run_emsdk('activate latest-upstream')
+
 test_lib_building(upstream_emcc, use_asmjs_optimizer=False)
 assert open(os.path.expanduser('~/.emscripten')).read().count('LLVM_ROOT') == 1
 assert 'upstream' in open(os.path.expanduser('~/.emscripten')).read()