bpo-40280: Skip dysfunctional pipe tests on Emscripten (GH-31770)

Author: tiran

Lib/test/test_io.py

@@ -426,6 +426,9 @@ def test_invalid_operations(self):
             self.assertRaises(exc, fp.seek, 1, self.SEEK_CUR)
             self.assertRaises(exc, fp.seek, -1, self.SEEK_END)
 
+    @unittest.skipIf(
+        support.is_emscripten, "fstat() of a pipe fd is not supported"
+    )
     def test_optional_abilities(self):
         # Test for OSError when optional APIs are not supported
         # The purpose of this test is to try fileno(), reading, writing and
@@ -3971,6 +3974,9 @@ def test_removed_u_mode(self):
                 self.open(os_helper.TESTFN, mode)
             self.assertIn('invalid mode', str(cm.exception))
 
+    @unittest.skipIf(
+        support.is_emscripten, "fstat() of a pipe fd is not supported"
+    )
     def test_open_pipe_with_append(self):
         # bpo-27805: Ignore ESPIPE from lseek() in open().
         r, w = os.pipe()
@@ -4134,9 +4140,15 @@ def test_pickling(self):
                 with self.open(os_helper.TESTFN, **kwargs) as f:
                     self.assertRaises(TypeError, pickle.dumps, f, protocol)
 
+    @unittest.skipIf(
+        support.is_emscripten, "fstat() of a pipe fd is not supported"
+    )
     def test_nonblock_pipe_write_bigbuf(self):
         self._test_nonblock_pipe_write(16*1024)
 
+    @unittest.skipIf(
+        support.is_emscripten, "fstat() of a pipe fd is not supported"
+    )
     def test_nonblock_pipe_write_smallbuf(self):
         self._test_nonblock_pipe_write(1024)