- Issue #15836: assertRaises(), assertRaisesRegex(), assertWarns() and
  assertWarnsRegex() assertments now check the type of the first argument
  to prevent possible user error.  Based on patch by Daniel Wagner-Hall.

- Issue #24134: assertRaises(), assertRaisesRegex(), assertWarns() and
  assertWarnsRegex() checks now emits a deprecation warning when callable is
  None or keyword arguments except msg is passed in the context manager mode.

- Issue #22903: The fake test case created by unittest.loader when it fails
  importing a test module is now picklable.

- unittest2 issue #94: Dependency on six needs to be versioned.

- Issue #22936: Make it possible to show local variables in tracebacks for
  both the traceback module and unittest.

- Issue #22894: TestCase.subTest() would cause the test suite to be stopped
  when in failfast mode, even in the absence of failures.

- Issue #22457: Honour load_tests in the start_dir of discovery.

- Issue #7559: unittest test loading ImportErrors are reported as import errors
  with their import exception rather than as attribute errors after the import
  has already failed.

- Issue #19746: Make it possible to examine the errors from unittest
  discovery without executing the test suite. The new `errors` attribute
  on TestLoader exposes these non-fatal errors encountered during discovery.

- Issue #16662: load_tests() is now unconditionally run when it is present in
  a package's __init__.py.  TestLoader.loadTestsFromModule() still accepts
  use_load_tests, but it is deprecated and ignored.  A new keyword-only
  attribute `pattern` is added and documented.  Patch given by Robert Collins,
  tweaked by Barry Warsaw.

- Issue #22032: __qualname__ instead of __name__ is now always used to format
  fully qualified class names of Python implemented classes.

- Issue #9815: assertRaises now tries to clear references to local variables
  in the exception's traceback.

- Issue #20145: `assertRaisesRegex` and `assertWarnsRegex` now raise a
  TypeError if the second argument is not a string or compiled regex.

- Issue #20165: The unittest module no longer considers tests marked with
  @expectedFailure successful if they pass.

- Fix breakage in TestSuite.countTestCases() introduced by issue #11798.

- Issue #19880: Fix a reference leak in unittest.TestCase. Explicitly break
  reference cycles between frames and the _Outcome instance.

- Issue #17457: unittest test discovery now works with namespace packages.
  Patch by Claudiu Popa.

- Issue #19352: Fix unittest discovery when a module can be reached
  through several paths (e.g. under Debian/Ubuntu with virtualenv).

- Issue #18996: TestCase.assertEqual() now more cleverly shorten differing
  strings in error report.

- Issue #18937: Add an assertLogs() context manager to unittest.TestCase
  to ensure that a block of code emits a message using the logging module.

- Issue #17974: Switch unittest from using getopt to using argparse.

- Issue #11798: TestSuite now drops references to own tests after execution.

- Issue #14971: unittest test discovery no longer gets confused when a function
  has a different __name__ than its name in the TestCase class dictionary.

- Issue #16997: unittest.TestCase now provides a subTest() context manager
  to procedurally generate, in an easy way, small test instances.

- Issue #16709: unittest discover order is no-longer filesystem specific. Patch
  by Jeff Ramnani.

- Issue #16935: unittest now counts the module as skipped if it raises SkipTest,
  instead of counting it as an error.  Patch by Zachary Ware.

- Issue #15132: Allow a list for the defaultTest argument of
  unittest.TestProgram. Patch by Jyrki Pulliainen.

- Issue #17052: unittest discovery should use self.testLoader.

- Issue #15505: `unittest.installHandler` no longer assumes SIGINT handler is
  set to a callable object.

- Issue #16064: unittest -m claims executable is "python", not "python3"

- Issue #12376: Pass on parameters in TextTestResult.__init__ super call

- Issue #14664: It is now possible to use @unittest.skip{If,Unless} on a
  test class that doesn't inherit from TestCase (i.e. a mixin).

- Issue #10543: Fix unittest test discovery with Jython bytecode files.

