Issue #26257: Eliminate buffer_tests.py and fix ByteArrayAsStringTest

ByteArrayAsStringTest.fixtype() was converting test data to bytes, not byte-
array, therefore many of the test cases inherited in this class were not
actually being run on the bytearray type.

The tests in buffer_tests.py were redundant with methods in string_tests
.MixinStrUnicodeUserStringTest and string_tests.CommonTest. Moved some tests
into a new base class string_tests.NonStringModuleTest, and run them for
bytearray.

Lib/test/string_tests.py

@@ -45,6 +45,9 @@ class CommonTest(unittest.TestCase):
         else:
             return obj
 
+    def test_fixtype(self):
+        self.assertIs(type(self.fixtype("123")), self.type2test)
+
     # check that object.method(*args) returns result
     def checkequal(self, result, object, methodname, *args):
         result = self.fixtype(result)
@@ -404,7 +407,9 @@ class CommonTest(unittest.TestCase):
                         'split', 'BLAH', 18)
 
         # mixed use of str and unicode
-        self.checkequal([u'a', u'b', u'c d'], 'a b c d', 'split', u' ', 2)
+        if self.type2test is not bytearray:
+            result = [u'a', u'b', u'c d']
+            self.checkequal(result, 'a b c d', 'split', u' ', 2)
 
         # argument type
         self.checkraises(TypeError, 'hello', 'split', 42, 42, 42)
@@ -494,7 +499,9 @@ class CommonTest(unittest.TestCase):
                         'rsplit', 'BLAH', 18)
 
         # mixed use of str and unicode
-        self.checkequal([u'a b', u'c', u'd'], 'a b c d', 'rsplit', u' ', 2)
+        if self.type2test is not bytearray:
+            result = [u'a b', u'c', u'd']
+            self.checkequal(result, 'a b c d', 'rsplit', u' ', 2)
 
         # argument type
         self.checkraises(TypeError, 'hello', 'rsplit', 42, 42, 42)
@@ -522,7 +529,7 @@ class CommonTest(unittest.TestCase):
         self.checkequal('hello', 'hello', 'strip', 'xyz')
 
         # strip/lstrip/rstrip with unicode arg
-        if test_support.have_unicode:
+        if self.type2test is not bytearray and test_support.have_unicode:
             self.checkequal(unicode('hello', 'ascii'), 'xyzzyhelloxyzzy',
                  'strip', unicode('xyz', 'ascii'))
             self.checkequal(unicode('helloxyzzy', 'ascii'), 'xyzzyhelloxyzzy',
@@ -542,6 +549,10 @@ class CommonTest(unittest.TestCase):
         self.checkequal('abc   ', 'abc', 'ljust', 6)
         self.checkequal('abc', 'abc', 'ljust', 3)
         self.checkequal('abc', 'abc', 'ljust', 2)
+        if self.type2test is bytearray:
+            # Special case because bytearray argument is not accepted
+            self.assertEqual(b'abc*******', bytearray(b'abc').ljust(10, '*'))
+        else:
             self.checkequal('abc*******', 'abc', 'ljust', 10, '*')
         self.checkraises(TypeError, 'abc', 'ljust')
 
@@ -550,6 +561,10 @@ class CommonTest(unittest.TestCase):
         self.checkequal('   abc', 'abc', 'rjust', 6)
         self.checkequal('abc', 'abc', 'rjust', 3)
         self.checkequal('abc', 'abc', 'rjust', 2)
+        if self.type2test is bytearray:
+            # Special case because bytearray argument is not accepted
+            self.assertEqual(b'*******abc', bytearray(b'abc').rjust(10, '*'))
+        else:
             self.checkequal('*******abc', 'abc', 'rjust', 10, '*')
         self.checkraises(TypeError, 'abc', 'rjust')
 
@@ -558,6 +573,11 @@ class CommonTest(unittest.TestCase):
         self.checkequal(' abc  ', 'abc', 'center', 6)
         self.checkequal('abc', 'abc', 'center', 3)
         self.checkequal('abc', 'abc', 'center', 2)
+        if self.type2test is bytearray:
+            # Special case because bytearray argument is not accepted
+            result = bytearray(b'abc').center(10, '*')
+            self.assertEqual(b'***abc****', result)
+        else:
             self.checkequal('***abc****', 'abc', 'center', 10, '*')
         self.checkraises(TypeError, 'abc', 'center')
 
@@ -772,13 +792,10 @@ class CommonTest(unittest.TestCase):
 
         self.checkraises(TypeError, '123', 'zfill')
 
-# XXX alias for py3k forward compatibility
-BaseTest = CommonTest
 
-class MixinStrUnicodeUserStringTest:
-    # additional tests that only work for
-    # stringlike objects, i.e. str, unicode, UserString
-    # (but not the string module)
+class NonStringModuleTest:
+    # additional test cases for all string classes from bytearray to
+    # UserString, but not valid for the "string" module
 
     def test_islower(self):
         self.checkequal(False, '', 'islower')
@@ -875,6 +892,12 @@ class MixinStrUnicodeUserStringTest:
 
         self.checkraises(TypeError, 'abc', 'splitlines', 42, 42)
 
+
+class MixinStrUnicodeUserStringTest(NonStringModuleTest):
+    # additional tests that only work for
+    # stringlike objects, i.e. str, unicode, UserString
+    # (but not the string module)
+
     def test_startswith(self):
         self.checkequal(True, 'hello', 'startswith', 'he')
         self.checkequal(True, 'hello', 'startswith', 'hello')

Lib/test/test_bytes.py

 """Unit tests for the bytes and bytearray types.
 
-XXX This is a mess.  Common tests should be moved to buffer_tests.py,
-which itself ought to be unified with string_tests.py (and the latter
-should be modernized).
+XXX This is a mess.  Common tests should be unified with string_tests.py (and
+the latter should be modernized).
 """
 
 import os
@@ -15,7 +14,6 @@ import tempfile
 import unittest
 import test.test_support
 import test.string_tests
-import test.buffer_tests
 
 
 if sys.flags.bytes_warning:
@@ -1030,8 +1028,7 @@ class AssortedBytesTest(unittest.TestCase):
     # the rest that make sense (the code can be cleaned up to use modern
     # unittest methods at the same time).
 
-class BytearrayPEP3137Test(unittest.TestCase,
-                       test.buffer_tests.MixinBytesBufferCommonTests):
+class BytearrayPEP3137Test(unittest.TestCase):
     def marshal(self, x):
         return bytearray(x)
 
@@ -1053,12 +1050,10 @@ class BytearrayPEP3137Test(unittest.TestCase,
             self.assertTrue(val is not newval,
                             expr+' returned val on a mutable object')
 
-class FixedStringTest(test.string_tests.BaseTest):
 
-    def fixtype(self, obj):
-        if isinstance(obj, str):
-            return obj.encode("utf-8")
-        return super(FixedStringTest, self).fixtype(obj)
+class ByteArrayAsStringTest(test.string_tests.CommonTest,
+        test.string_tests.NonStringModuleTest):
+    type2test = bytearray
 
     # Currently the bytes containment testing uses a single integer
     # value. This may not be the final design, but until then the
@@ -1076,10 +1071,6 @@ class FixedStringTest(test.string_tests.BaseTest):
         pass
 
 
-class ByteArrayAsStringTest(FixedStringTest):
-    type2test = bytearray
-
-
 class ByteArraySubclass(bytearray):
     pass
 
@@ -1160,7 +1151,6 @@ class ByteArraySubclassTest(unittest.TestCase):
 def test_main():
     #test.test_support.run_unittest(BytesTest)
     #test.test_support.run_unittest(AssortedBytesTest)
-    #test.test_support.run_unittest(BytesAsStringTest)
     test.test_support.run_unittest(
         ByteArrayTest,
         ByteArrayAsStringTest,