Add tests for BufferedReader and BufferedRandom

Author: tomasr8

Lib/test/test_io/test_bufferedio.py

@@ -642,6 +642,16 @@ def test_read1_error_does_not_cause_reentrant_failure(self):
             # Used to crash before gh-143689:
             self.assertEqual(bufio.read1(1), b"h")
 
+    def test_gh_143375(self):
+        bufio = self.tp(self.MockRawIO())
+
+        class EvilIndex:
+            def __index__(self):
+                bufio.close()
+                return 0
+
+        with self.assertRaisesRegex(ValueError, "seek of closed file"):
+            bufio.seek(EvilIndex())
 
 class PyBufferedReaderTest(BufferedReaderTest, PyTestCase):
     tp = pyio.BufferedReader
@@ -1504,6 +1514,17 @@ def test_args_error(self):
         with self.assertRaisesRegex(TypeError, "BufferedRandom"):
             self.tp(self.BytesIO(), 1024, 1024, 1024)
 
+    def test_gh_143375(self):
+        bufio = self.tp(self.MockRawIO())
+
+        class EvilIndex:
+            def __index__(self):
+                bufio.close()
+                return 0
+
+        with self.assertRaisesRegex(ValueError, "seek of closed file"):
+            bufio.seek(EvilIndex())
+
 
 class PyBufferedRandomTest(BufferedRandomTest, PyTestCase):
     tp = pyio.BufferedRandom