Issue #20557: Use specific asserts in io tests.

Lib/test/test_bufio.py

@@ -34,7 +34,7 @@ class BufferSizeTest:
             line = f.readline()
             self.assertEqual(line, s)
             line = f.readline()
-            self.assertTrue(not line) # Must be at EOF
+            self.assertFalse(line) # Must be at EOF
             f.close()
         finally:
             support.unlink(support.TESTFN)

Lib/test/test_file.py

@@ -83,8 +83,8 @@ class AutoFileTests:
     def testErrors(self):
         f = self.f
         self.assertEqual(f.name, TESTFN)
-        self.assertTrue(not f.isatty())
-        self.assertTrue(not f.closed)
+        self.assertFalse(f.isatty())
+        self.assertFalse(f.closed)
 
         if hasattr(f, "readinto"):
             self.assertRaises((OSError, TypeError), f.readinto, "")

Lib/test/test_fileio.py

@@ -113,15 +113,15 @@ class AutoFileTests(unittest.TestCase):
 
     def testErrors(self):
         f = self.f
-        self.assertTrue(not f.isatty())
-        self.assertTrue(not f.closed)
+        self.assertFalse(f.isatty())
+        self.assertFalse(f.closed)
         #self.assertEqual(f.name, TESTFN)
         self.assertRaises(ValueError, f.read, 10) # Open for reading
         f.close()
         self.assertTrue(f.closed)
         f = _FileIO(TESTFN, 'r')
         self.assertRaises(TypeError, f.readinto, "")
-        self.assertTrue(not f.closed)
+        self.assertFalse(f.closed)
         f.close()
         self.assertTrue(f.closed)
 

Lib/test/test_io.py

@@ -453,7 +453,7 @@ class IOTest(unittest.TestCase):
         with self.open(support.TESTFN, "ab") as f:
             self.assertEqual(f.tell(), 3)
         with self.open(support.TESTFN, "a") as f:
-            self.assertTrue(f.tell() > 0)
+            self.assertGreater(f.tell(), 0)
 
     def test_destructor(self):
         record = []
@@ -573,7 +573,7 @@ class IOTest(unittest.TestCase):
             wr = weakref.ref(f)
             del f
             support.gc_collect()
-        self.assertTrue(wr() is None, wr)
+        self.assertIsNone(wr(), wr)
         with self.open(support.TESTFN, "rb") as f:
             self.assertEqual(f.read(), b"abcxxx")
 
@@ -717,7 +717,7 @@ class CIOTest(IOTest):
         del MyIO
         del obj
         support.gc_collect()
-        self.assertTrue(wr() is None, wr)
+        self.assertIsNone(wr(), wr)
 
 class PyIOTest(IOTest):
     pass
@@ -1164,7 +1164,7 @@ class CBufferedReaderTest(BufferedReaderTest, SizeofTest):
             wr = weakref.ref(f)
             del f
             support.gc_collect()
-        self.assertTrue(wr() is None, wr)
+        self.assertIsNone(wr(), wr)
 
     def test_args_error(self):
         # Issue #17275
@@ -1467,7 +1467,7 @@ class CBufferedWriterTest(BufferedWriterTest, SizeofTest):
             wr = weakref.ref(f)
             del f
             support.gc_collect()
-        self.assertTrue(wr() is None, wr)
+        self.assertIsNone(wr(), wr)
         with self.open(support.TESTFN, "rb") as f:
             self.assertEqual(f.read(), b"123xxx")
 
@@ -2199,7 +2199,7 @@ class TextIOWrapperTest(unittest.TestCase):
         t = self.TextIOWrapper(b, encoding="utf-8")
         self.assertEqual(t.encoding, "utf-8")
         t = self.TextIOWrapper(b)
-        self.assertTrue(t.encoding is not None)
+        self.assertIsNotNone(t.encoding)
         codecs.lookup(t.encoding)
 
     def test_encoding_errors_reading(self):
@@ -2958,7 +2958,7 @@ class CTextIOWrapperTest(TextIOWrapperTest):
             wr = weakref.ref(t)
             del t
             support.gc_collect()
-        self.assertTrue(wr() is None, wr)
+        self.assertIsNone(wr(), wr)
         with self.open(support.TESTFN, "rb") as f:
             self.assertEqual(f.read(), b"456def")
 
@@ -3106,7 +3106,7 @@ class MiscIOTest(unittest.TestCase):
     def test___all__(self):
         for name in self.io.__all__:
             obj = getattr(self.io, name, None)
-            self.assertTrue(obj is not None, name)
+            self.assertIsNotNone(obj, name)
             if name == "open":
                 continue
             elif "error" in name.lower() or name == "UnsupportedOperation":
@@ -3196,7 +3196,7 @@ class MiscIOTest(unittest.TestCase):
         wr = weakref.ref(c)
         del c, b
         support.gc_collect()
-        self.assertTrue(wr() is None, wr)
+        self.assertIsNone(wr(), wr)
 
     def test_abcs(self):
         # Test the visible base classes are ABCs.
@@ -3348,7 +3348,7 @@ class MiscIOTest(unittest.TestCase):
             received += iter(rf.read, None)
 
         sent, received = b''.join(sent), b''.join(received)
-        self.assertTrue(sent == received)
+        self.assertEqual(sent, received)
         self.assertTrue(wf.closed)
         self.assertTrue(rf.closed)
 

Lib/test/test_memoryio.py

@@ -693,7 +693,8 @@ class CBytesIOTest(PyBytesIOTest):
         self.assertEqual(len(state), 3)
         bytearray(state[0]) # Check if state[0] supports the buffer interface.
         self.assertIsInstance(state[1], int)
-        self.assertTrue(isinstance(state[2], dict) or state[2] is None)
+        if state[2] is not None:
+            self.assertIsInstance(state[2], dict)
         memio.close()
         self.assertRaises(ValueError, memio.__getstate__)
 
@@ -749,7 +750,8 @@ class CStringIOTest(PyStringIOTest):
         self.assertIsInstance(state[0], str)
         self.assertIsInstance(state[1], str)
         self.assertIsInstance(state[2], int)
-        self.assertTrue(isinstance(state[3], dict) or state[3] is None)
+        if state[3] is not None:
+            self.assertIsInstance(state[3], dict)
         memio.close()
         self.assertRaises(ValueError, memio.__getstate__)