"test" --- Regression tests package for Python
**********************************************

注釈:

  The "test" package is meant for internal use by Python only. It is
  documented for the benefit of the core developers of Python. Any use
  of this package outside of Python's standard library is discouraged
  as code mentioned here can change or be removed without notice
  between releases of Python.

======================================================================

The "test" package contains all regression tests for Python as well as
the modules "test.support" and "test.regrtest". "test.support" is used
to enhance your tests while "test.regrtest" drives the testing suite.

Each module in the "test" package whose name starts with "test_" is a
testing suite for a specific module or feature. All new tests should
be written using the "unittest" or "doctest" module.  Some older tests
are written using a "traditional" testing style that compares output
printed to "sys.stdout"; this style of test is considered deprecated.

参考:

  "unittest" モジュール
     PyUnit 回帰テストを書く。

  "doctest" モジュール
     ドキュメンテーション文字列に埋め込まれたテスト。


Writing Unit Tests for the "test" package
=========================================

"unittest" モジュールを使ってテストを書く場合、幾つかのガイドラインに
従うことが推奨されます。 1つは、テストモジュールの名前を、 "test_" で
始め、テスト対象となるモジュール名で終えることです。テストモジュール中
のテストメソッドは名前を "test_" で始めて、そのメソッドが何をテストし
ているかという説明で終えます。これはテスト実行プログラムが、そのメソッ
ドをテストメソッドとして認識するために必要です。また、テストメソッドに
はドキュメンテーション文字列を入れるべきではありません。コメント（例え
ば "# True あるいは False だけを返すテスト関数" ）を使用して、テストメ
ソッドのドキュメントを記述してください。これは、ドキュメンテーション文
字列が存在する場合はその内容が出力されてしまうため、どのテストを実行し
ているのかをいちいち表示したくないからです。

以下のような決まり文句を使います:

   import unittest
   from test import support

   class MyTestCase1(unittest.TestCase):

       # Only use setUp() and tearDown() if necessary

       def setUp(self):
           ... code to execute in preparation for tests ...

       def tearDown(self):
           ... code to execute to clean up after tests ...

       def test_feature_one(self):
           # Test feature one.
           ... testing code ...

       def test_feature_two(self):
           # Test feature two.
           ... testing code ...

       ... more test methods ...

   class MyTestCase2(unittest.TestCase):
       ... same structure as MyTestCase1 ...

   ... more test classes ...

   if __name__ == '__main__':
       unittest.main()

このコードのパターンを使うと "test.regrtest" からテストスイートを実行
でき、 "unittest" のコマンドラインインターフェースをサポートしているス
クリプトとして自分自身を起動したり、 "python -m unittest" というコマン
ドラインインターフェースを通して起動したりできます。

回帰テストの目的はコードを解き明かすことです。そのためには以下のいくつ
かのガイドラインに従ってください:

* テストスイートから、すべてのクラス、関数および定数を実行するべきです
  。これには外部に公開される外部APIだけでなく「プライベートな」コード
  も含みます。

* ホワイトボックス・テスト（対象のコードの詳細を元にテストを書くこと）
  を推奨します。ブラックボックス・テスト（公開されるインターフェース仕
  様だけをテストすること）は、すべての境界条件を確実にテストするには完
  全ではありません。

* すべての取りうる値を、無効値も含めてテストするようにしてください。そ
  のようなテストを書くことで、全ての有効値が通るだけでなく、不適切な値
  が正しく処理されることも確認できます。

* コード内のできる限り多くのパスを網羅してください。分岐するように入力
  を調整したテストを書くことで、コードの多くのパスをたどることができま
  す。

* テスト対象のコードにバグが発見された場合は、明示的にテスト追加するよ
  うにしてください。そのようなテストを追加することで、将来コードを変更
  した際にエラーが再発することを防止できます。

* テストの後始末 (例えば一時ファイルをすべて閉じたり削除したりすること
  ) を必ず行ってください。

* テストがオペレーティングシステムの特定の状況に依存する場合、テスト開
  始時に条件を満たしているかを検証してください。

* インポートするモジュールをできるかぎり少なくし、可能な限り早期にイン
  ポートを行ってください。そうすることで、テストの外部依存性を最小限に
  し、モジュールのインポートによる副作用から生じる変則的な動作を最小限
  にできます。

* できる限りテストコードを再利用するようにしましょう。時として、入力の
  違いだけを記述すれば良くなるくらい、テストコードを小さくすることがで
  きます。例えば以下のように、サブクラスで入力を指定することで、コード
  の重複を最小化することができます:

     class TestFuncAcceptsSequencesMixin:

         func = mySuperWhammyFunction

         def test_func(self):
             self.func(self.arg)

     class AcceptLists(TestFuncAcceptsSequencesMixin, unittest.TestCase):
         arg = [1, 2, 3]

     class AcceptStrings(TestFuncAcceptsSequencesMixin, unittest.TestCase):
         arg = 'abc'

     class AcceptTuples(TestFuncAcceptsSequencesMixin, unittest.TestCase):
         arg = (1, 2, 3)

  When using this pattern, remember that all classes that inherit from
  "unittest.TestCase" are run as tests.  The
  "TestFuncAcceptsSequencesMixin" class in the example above does not
  have any data and so can't be run by itself, thus it does not
  inherit from "unittest.TestCase".

参考:

  Test Driven Development
     コードより前にテストを書く方法論に関する Kent Beck の著書。


コマンドラインインターフェースを利用してテストを実行する
========================================================

The "test" package can be run as a script to drive Python's regression
test suite, thanks to the "-m" option: **python -m test**. Under the
hood, it uses "test.regrtest"; the call **python -m test.regrtest**
used in previous Python versions still works.  Running the script by
itself automatically starts running all regression tests in the "test"
package. It does this by finding all modules in the package whose name
starts with "test_", importing them, and executing the function
"test_main()" if present or loading the tests via
unittest.TestLoader.loadTestsFromModule if "test_main" does not exist.
The names of tests to execute may also be passed to the script.
Specifying a single regression test (**python -m test test_spam**)
will minimize output and only print whether the test passed or failed.

Running "test" directly allows what resources are available for tests
to use to be set. You do this by using the "-u" command-line option.
Specifying "all" as the value for the "-u" option enables all possible
resources: **python -m test -uall**. If all but one resource is
desired (a more common case), a comma-separated list of resources that
are not desired may be listed after "all". The command **python -m
test -uall,-audio,-largefile** will run "test" with all resources
except the "audio" and "largefile" resources. For a list of all
resources and more command-line options, run **python -m test -h**.

テストを実行しようとするプラットフォームによっては、回帰テストを実行す
る別の方法があります。 Unix では、Python をビルドしたトップレベルディ
レクトリで **make test** を実行できます。 Windows上では、 "PCbuild" デ
ィレクトリから **rt.bat** を実行すると、すべての回帰テストを実行します
。

Added in version 3.14: Output is colorized by default and can be
controlled using environment variables.


"test.support" --- Utilities for the Python test suite
******************************************************

The "test.support" module provides support for Python's regression
test suite.

注釈:

  "test.support" is not a public module.  It is documented here to
  help Python developers write tests.  The API of this module is
  subject to change without backwards compatibility concerns between
  releases.

このモジュールは次の例外を定義しています:

exception test.support.TestFailed

   テストが失敗したとき送出される例外です。これは、 "unittest" ベース
   のテストでは廃止予定で、 "unittest.TestCase" の assertXXX メソッド
   が推奨されます。

exception test.support.ResourceDenied

   "unittest.SkipTest" のサブクラスです。 (ネットワーク接続のような)
   リソースが利用できないとき送出されます。 "requires()" 関数によって
   送出されます。

The "test.support" module defines the following constants:

test.support.verbose

   冗長な出力が有効な場合は "True" です。実行中のテストについてのより
   詳細な情報が欲しいときにチェックします。 *verbose* は
   "test.regrtest" によって設定されます。

test.support.is_jython

   実行中のインタプリタが Jython ならば "True" になります。

test.support.is_android

   "True" if "sys.platform" is "android".

test.support.is_emscripten

   "True" if "sys.platform" is "emscripten".

test.support.is_wasi

   "True" if "sys.platform" is "wasi".

test.support.is_apple_mobile

   "True" if "sys.platform" is "ios", "tvos", or "watchos".

test.support.is_apple

   "True" if "sys.platform" is "darwin" or "is_apple_mobile" is
   "True".

test.support.unix_shell

   Windows 以外ではシェルのパスです; そうでない場合は "None" です。

test.support.LOOPBACK_TIMEOUT

   Timeout in seconds for tests using a network server listening on
   the network local loopback interface like "127.0.0.1".

   The timeout is long enough to prevent test failure: it takes into
   account that the client and the server can run in different threads
   or even different processes.

   The timeout should be long enough for "connect()", "recv()" and
   "send()" methods of "socket.socket".

   デフォルト値は5秒です。

   "INTERNET_TIMEOUT" も参照してください。

test.support.INTERNET_TIMEOUT

   Timeout in seconds for network requests going to the internet.

   The timeout is short enough to prevent a test to wait for too long
   if the internet request is blocked for whatever reason.

   Usually, a timeout using "INTERNET_TIMEOUT" should not mark a test
   as failed, but skip the test instead: see "transient_internet()".

   デフォルト値は1分です。

   "LOOPBACK_TIMEOUT" も参照してください。

test.support.SHORT_TIMEOUT

   Timeout in seconds to mark a test as failed if the test takes "too
   long".

   The timeout value depends on the regrtest "--timeout" command line
   option.

   If a test using "SHORT_TIMEOUT" starts to fail randomly on slow
   buildbots, use "LONG_TIMEOUT" instead.

   デフォルト値は30秒です。

test.support.LONG_TIMEOUT

   Timeout in seconds to detect when a test hangs.

   It is long enough to reduce the risk of test failure on the slowest
   Python buildbots. It should not be used to mark a test as failed if
   the test takes "too long".  The timeout value depends on the
   regrtest "--timeout" command line option.

   デフォルト値は5分です。

   See also "LOOPBACK_TIMEOUT", "INTERNET_TIMEOUT" and
   "SHORT_TIMEOUT".

test.support.PGO

   テストが PGO (Profile Guided Optimization) の役に立たないときにスキ
   ップできるなら設定します。

test.support.PIPE_MAX_SIZE

   書き込みをブロックするための、基底にある OS のパイプバッファサイズ
   より大きいであろう定数。

test.support.Py_DEBUG

   "True" if Python was built with the "Py_DEBUG" macro defined, that
   is, if Python was built in debug mode.

   Added in version 3.12.

test.support.SOCK_MAX_SIZE

   書き込みをブロックするための、基底にある OS のソケットバッファサイ
   ズより大きいであろう定数。

test.support.TEST_SUPPORT_DIR

   Set to the top level directory that contains "test.support".

test.support.TEST_HOME_DIR

   テストパッケージのトップディレクトリを設定します。

test.support.TEST_DATA_DIR

   テストパッケージ内の "data" ディレクトリを設定します。

test.support.MAX_Py_ssize_t

   大量のメモリを使うテストのための  "sys.maxsize" を設定します。

test.support.max_memuse

   大量のメモリを使うテストのためのメモリ上限となる "set_memlimit()"
   を設定します。 "MAX_Py_ssize_t" が設定上限です。

test.support.real_max_memuse

   大量のメモリを使うテストのためのメモリ上限となる "set_memlimit()"
   を設定します。 "MAX_Py_ssize_t" の設定上限はありません。

test.support.MISSING_C_DOCSTRINGS

   Set to "True" if Python is built without docstrings (the
   "WITH_DOC_STRINGS" macro is not defined). See the "configure
   --without-doc-strings" option.

   See also the "HAVE_DOCSTRINGS" variable.

test.support.HAVE_DOCSTRINGS

   Set to "True" if function docstrings are available. See the "python
   -OO" option, which strips docstrings of functions implemented in
   Python.

   See also the "MISSING_C_DOCSTRINGS" variable.

test.support.TEST_HTTP_URL

   ネットワークテスト専用の HTTP サーバーの URL を定義します。

test.support.ALWAYS_EQ

   Object that is equal to anything.  Used to test mixed type
   comparison.

test.support.NEVER_EQ

   Object that is not equal to anything (even to "ALWAYS_EQ"). Used to
   test mixed type comparison.

test.support.LARGEST

   Object that is greater than anything (except itself). Used to test
   mixed type comparison.

test.support.SMALLEST

   Object that is less than anything (except itself). Used to test
   mixed type comparison.

The "test.support" module defines the following functions:

test.support.busy_retry(timeout, err_msg=None, /, *, error=True)

   Run the loop body until "break" stops the loop.

   After *timeout* seconds, raise an "AssertionError" if *error* is
   true, or just stop the loop if *error* is false.

   以下はプログラム例です:

      for _ in support.busy_retry(support.SHORT_TIMEOUT):
          if check():
              break

   Example of error=False usage:

      for _ in support.busy_retry(support.SHORT_TIMEOUT, error=False):
          if check():
              break
      else:
          raise RuntimeError('my custom error')

test.support.sleeping_retry(timeout, err_msg=None, /, *, init_delay=0.010, max_delay=1.0, error=True)

   Wait strategy that applies exponential backoff.

   Run the loop body until "break" stops the loop. Sleep at each loop
   iteration, but not at the first iteration. The sleep delay is
   doubled at each iteration (up to *max_delay* seconds).

   See "busy_retry()" documentation for the parameters usage.

   Example raising an exception after SHORT_TIMEOUT seconds:

      for _ in support.sleeping_retry(support.SHORT_TIMEOUT):
          if check():
              break

   Example of error=False usage:

      for _ in support.sleeping_retry(support.SHORT_TIMEOUT, error=False):
          if check():
              break
      else:
          raise RuntimeError('my custom error')

test.support.is_resource_enabled(resource)

   *resource* が有効で利用可能ならば "True" を返します。利用可能なリソ
   ースのリストは、 "test.regrtest" がテストを実行している間のみ設定さ
   れます。

test.support.get_resource_value(resource)

   Return the value specified for *resource* (as "-u
   *resource*=*value*"). Return "None" if *resource* is disabled or no
   value is specified.

test.support.python_is_optimized()

   Return "True" if Python was not built with "-O0" or "-Og".

test.support.with_pymalloc()

   Return "_testcapi.WITH_PYMALLOC".

test.support.requires(resource, msg=None)

   *resource* が利用できなければ、 "ResourceDenied" を送出します。その
   場合、 *msg* は "ResourceDenied" の引数になります。 "__name__" が
   "'__main__'" である関数にから呼び出された場合には常に "True" を返し
   ます。テストを "test.regrtest" から実行するときに使われます。

test.support.sortdict(dict)

   Return a repr of *dict* with keys sorted.

test.support.findfile(filename, subdir=None)

   *filename* という名前のファイルへのパスを返します。一致するものが見
   つからなければ、 *filename* 自体を返します。 *filename* 自体もファ
   イルへのパスでありえるので、 *filename* が返っても失敗ではありませ
   ん。

   *subdir* を設定することで、パスのディレクトリを直接見に行くのではな
   く、相対パスを使って見付けにいくように指示できます。

test.support.get_pagesize()

   Get size of a page in bytes.

   Added in version 3.12.

test.support.setswitchinterval(interval)

   Set the "sys.setswitchinterval()" to the given *interval*.  Defines
   a minimum interval for Android systems to prevent the system from
   hanging.

test.support.check_impl_detail(**guards)

   Use this check to guard CPython's implementation-specific tests or
   to run them only on the implementations guarded by the arguments.
   This function returns "True" or "False" depending on the host
   platform. Example usage:

      check_impl_detail()               # Only on CPython (default).
      check_impl_detail(jython=True)    # Only on Jython.
      check_impl_detail(cpython=False)  # Everywhere except CPython.

test.support.set_memlimit(limit)

   Set the values for "max_memuse" and "real_max_memuse" for big
   memory tests.

test.support.record_original_stdout(stdout)

   Store the value from *stdout*.  It is meant to hold the stdout at
   the time the regrtest began.

test.support.get_original_stdout()

   Return the original stdout set by "record_original_stdout()" or
   "sys.stdout" if it's not set.

test.support.args_from_interpreter_flags()

   Return a list of command line arguments reproducing the current
   settings in "sys.flags" and "sys.warnoptions".

test.support.optim_args_from_interpreter_flags()

   Return a list of command line arguments reproducing the current
   optimization settings in "sys.flags".

test.support.captured_stdin()
test.support.captured_stdout()
test.support.captured_stderr()

   名前付きストリ－ムを "io.StringIO" オブジェクトで一時的に置き換える
   コンテキストマネージャです。

   出力ストリームの使用例:

      with captured_stdout() as stdout, captured_stderr() as stderr:
          print("hello")
          print("error", file=sys.stderr)
      assert stdout.getvalue() == "hello\n"
      assert stderr.getvalue() == "error\n"

   入力ストリ－ムの使用例:

      with captured_stdin() as stdin:
          stdin.write('hello\n')
          stdin.seek(0)
          # call test code that consumes from sys.stdin
          captured = input()
      self.assertEqual(captured, "hello")

test.support.disable_faulthandler()

   A context manager that temporary disables "faulthandler".

test.support.gc_collect()

   Force as many objects as possible to be collected.  This is needed
   because timely deallocation is not guaranteed by the garbage
   collector.  This means that "__del__" methods may be called later
   than expected and weakrefs may remain alive for longer than
   expected.

test.support.disable_gc()

   A context manager that disables the garbage collector on entry. On
   exit, the garbage collector is restored to its prior state.

test.support.swap_attr(obj, attr, new_val)

   Context manager to swap out an attribute with a new object.

   使い方:

      with swap_attr(obj, "attr", 5):
          ...

   This will set "obj.attr" to 5 for the duration of the "with" block,
   restoring the old value at the end of the block.  If "attr" doesn't
   exist on "obj", it will be created and then deleted at the end of
   the block.

   The old value (or "None" if it doesn't exist) will be assigned to
   the target of the "as" clause, if there is one.

test.support.swap_item(obj, attr, new_val)

   Context manager to swap out an item with a new object.

   使い方:

      with swap_item(obj, "item", 5):
          ...

   This will set "obj["item"]" to 5 for the duration of the "with"
   block, restoring the old value at the end of the block. If "item"
   doesn't exist on "obj", it will be created and then deleted at the
   end of the block.

   The old value (or "None" if it doesn't exist) will be assigned to
   the target of the "as" clause, if there is one.

test.support.flush_std_streams()

   Call the "flush()" method on "sys.stdout" and then on "sys.stderr".
   It can be used to make sure that the logs order is consistent
   before writing into stderr.

   Added in version 3.11.

test.support.print_warning(msg)

   Print a warning into "sys.__stderr__". Format the message as:
   "f"Warning -- {msg}"". If *msg* is made of multiple lines, add
   ""Warning -- "" prefix to each line.

   Added in version 3.9.

test.support.wait_process(pid, *, exitcode, timeout=None)

   Wait until process *pid* completes and check that the process exit
   code is *exitcode*.

   Raise an "AssertionError" if the process exit code is not equal to
   *exitcode*.

   If the process runs longer than *timeout* seconds ("SHORT_TIMEOUT"
   by default), kill the process and raise an "AssertionError". The
   timeout feature is not available on Windows.

   Added in version 3.9.

test.support.calcobjsize(fmt)

   Return the size of the "PyObject" whose structure members are
   defined by *fmt*. The returned value includes the size of the
   Python object header and alignment.

test.support.calcvobjsize(fmt)

   Return the size of the "PyVarObject" whose structure members are
   defined by *fmt*. The returned value includes the size of the
   Python object header and alignment.

test.support.checksizeof(test, o, size)

   For testcase *test*, assert that the "sys.getsizeof" for *o* plus
   the GC header size equals *size*.

@test.support.anticipate_failure(condition)

   ある条件で "unittest.expectedFailure()" の印をテストに付けるデコレ
   ータ。 このデコレータを使うときはいつも、関連する問題を指し示すコメ
   ントを付けておくべきです。

test.support.system_must_validate_cert(f)

   A decorator that skips the decorated test on TLS certification
   validation failures.

@test.support.run_with_locale(catstr, *locales)

   別のロケールで関数を実行し、完了したら適切に元の状態に戻すためのデ
   コレータ。 *catstr* は (例えば ""LC_ALL"" のような) ロケールカテゴ
   リを文字列で表したものです。 渡された *locales* が順々に試され、一
   番最初に出てきた妥当なロケールが使われます。

@test.support.run_with_tz(tz)

   A decorator for running a function in a specific timezone,
   correctly resetting it after it has finished.

@test.support.requires_freebsd_version(*min_version)

   Decorator for the minimum version when running test on FreeBSD.  If
   the FreeBSD version is less than the minimum, the test is skipped.

@test.support.requires_linux_version(*min_version)

   Decorator for the minimum version when running test on Linux.  If
   the Linux version is less than the minimum, the test is skipped.

@test.support.requires_mac_version(*min_version)

   Decorator for the minimum version when running test on macOS.  If
   the macOS version is less than the minimum, the test is skipped.

@test.support.requires_gil_enabled

   Decorator for skipping tests on the free-threaded build.  If the
   *GIL* is disabled, the test is skipped.

@test.support.requires_IEEE_754

   Decorator for skipping tests on non-IEEE 754 platforms.

@test.support.requires_zlib

   Decorator for skipping tests if "zlib" doesn't exist.

@test.support.requires_gzip

   Decorator for skipping tests if "gzip" doesn't exist.

@test.support.requires_bz2

   Decorator for skipping tests if "bz2" doesn't exist.

@test.support.requires_lzma

   Decorator for skipping tests if "lzma" doesn't exist.

@test.support.requires_resource(resource)

   Decorator for skipping tests if *resource* is not available.

@test.support.requires_docstrings

   Decorator for only running the test if "HAVE_DOCSTRINGS".

@test.support.requires_limited_api

   Decorator for only running the test if Limited C API is available.

@test.support.cpython_only

   Decorator for tests only applicable to CPython.

@test.support.impl_detail(msg=None, **guards)

   Decorator for invoking "check_impl_detail()" on *guards*.  If that
   returns "False", then uses *msg* as the reason for skipping the
   test.

@test.support.thread_unsafe(reason=None)

   Decorator for marking tests as thread-unsafe.  This test always
   runs in one thread even when invoked with "--parallel-threads".

@test.support.no_tracing

   Decorator to temporarily turn off tracing for the duration of the
   test.

@test.support.refcount_test

   Decorator for tests which involve reference counting.  The
   decorator does not run the test if it is not run by CPython.  Any
   trace function is unset for the duration of the test to prevent
   unexpected refcounts caused by the trace function.

@test.support.bigmemtest(size, memuse, dry_run=True)

   Decorator for bigmem tests.

   *size* is a requested size for the test (in arbitrary, test-
   interpreted units.)  *memuse* is the number of bytes per unit for
   the test, or a good estimate of it.  For example, a test that needs
   two byte buffers, of 4 GiB each, could be decorated with
   "@bigmemtest(size=_4G, memuse=2)".

   The *size* argument is normally passed to the decorated test method
   as an extra argument.  If *dry_run* is "True", the value passed to
   the test method may be less than the requested value.  If *dry_run*
   is "False", it means the test doesn't support dummy runs when "-M"
   is not specified.

@test.support.bigaddrspacetest

   Decorator for tests that fill the address space.

test.support.linked_to_musl()

   Return "False" if there is no evidence the interpreter was compiled
   with "musl", otherwise return a version triple, either "(0, 0, 0)"
   if the version is unknown, or the actual version if it is known.
   Intended for use in "skip" decorators.  "emscripten" and "wasi" are
   assumed to be compiled with "musl"; otherwise "platform.libc_ver"
   is checked.

test.support.check_syntax_error(testcase, statement, errtext='', *, lineno=None, offset=None)

   Test for syntax errors in *statement* by attempting to compile
   *statement*. *testcase* is the "unittest" instance for the test.
   *errtext* is the regular expression which should match the string
   representation of the raised "SyntaxError".  If *lineno* is not
   "None", compares to the line of the exception.  If *offset* is not
   "None", compares to the offset of the exception.

test.support.open_urlresource(url, *args, **kw)

   Open *url*.  If open fails, raises "TestFailed".

test.support.reap_children()

   Use this at the end of "test_main" whenever sub-processes are
   started. This will help ensure that no extra children (zombies)
   stick around to hog resources and create problems when looking for
   refleaks.

test.support.get_attribute(obj, name)

   Get an attribute, raising "unittest.SkipTest" if "AttributeError"
   is raised.

test.support.catch_unraisable_exception()

   Context manager catching unraisable exception using
   "sys.unraisablehook()".

   Storing the exception value ("cm.unraisable.exc_value") creates a
   reference cycle. The reference cycle is broken explicitly when the
   context manager exits.

   Storing the object ("cm.unraisable.object") can resurrect it if it
   is set to an object which is being finalized. Exiting the context
   manager clears the stored object.

   使い方:

      with support.catch_unraisable_exception() as cm:
          # code creating an "unraisable exception"
          ...

          # check the unraisable exception: use cm.unraisable
          ...

      # cm.unraisable attribute no longer exists at this point
      # (to break a reference cycle)

   Added in version 3.8.

test.support.load_package_tests(pkg_dir, loader, standard_tests, pattern)

   Generic implementation of the "unittest" "load_tests" protocol for
   use in test packages.  *pkg_dir* is the root directory of the
   package; *loader*, *standard_tests*, and *pattern* are the
   arguments expected by "load_tests".  In simple cases, the test
   package's "__init__.py" can be the following:

      import os
      from test.support import load_package_tests

      def load_tests(*args):
          return load_package_tests(os.path.dirname(__file__), *args)

test.support.detect_api_mismatch(ref_api, other_api, *, ignore=())

   Returns the set of attributes, functions or methods of *ref_api*
   not found on *other_api*, except for a defined list of items to be
   ignored in this check specified in *ignore*.

   By default this skips private attributes beginning with '_' but
   includes all magic methods, i.e. those starting and ending in '__'.

   Added in version 3.5.

test.support.patch(test_instance, object_to_patch, attr_name, new_value)

   Override *object_to_patch.attr_name* with *new_value*.  Also add
   cleanup procedure to *test_instance* to restore *object_to_patch*
   for *attr_name*.  The *attr_name* should be a valid attribute for
   *object_to_patch*.

test.support.run_in_subinterp(code)

   Run *code* in subinterpreter.  Raise "unittest.SkipTest" if
   "tracemalloc" is enabled.

test.support.check_free_after_iterating(test, iter, cls, args=())

   Assert instances of *cls* are deallocated after iterating.

test.support.missing_compiler_executable(cmd_names=[])

   Check for the existence of the compiler executables whose names are
   listed in *cmd_names* or all the compiler executables when
   *cmd_names* is empty and return the first missing executable or
   "None" when none is found missing.

test.support.check__all__(test_case, module, name_of_module=None, extra=(), not_exported=())

   Assert that the "__all__" variable of *module* contains all public
   names.

   The module's public names (its API) are detected automatically
   based on whether they match the public name convention and were
   defined in *module*.

   The *name_of_module* argument can specify (as a string or tuple
   thereof) what module(s) an API could be defined in order to be
   detected as a public API. One case for this is when *module*
   imports part of its public API from other modules, possibly a C
   backend (like "csv" and its "_csv").

   The *extra* argument can be a set of names that wouldn't otherwise
   be automatically detected as "public", like objects without a
   proper "__module__" attribute. If provided, it will be added to the
   automatically detected ones.

   The *not_exported* argument can be a set of names that must not be
   treated as part of the public API even though their names indicate
   otherwise.

   使用例:

      import bar
      import foo
      import unittest
      from test import support

      class MiscTestCase(unittest.TestCase):
          def test__all__(self):
              support.check__all__(self, foo)

      class OtherTestCase(unittest.TestCase):
          def test__all__(self):
              extra = {'BAR_CONST', 'FOO_CONST'}
              not_exported = {'baz'}  # Undocumented name.
              # bar imports part of its API from _bar.
              support.check__all__(self, bar, ('bar', '_bar'),
                                   extra=extra, not_exported=not_exported)

   Added in version 3.6.

test.support.skip_if_broken_multiprocessing_synchronize()

   Skip tests if the "multiprocessing.synchronize" module is missing,
   if there is no available semaphore implementation, or if creating a
   lock raises an "OSError".

   Added in version 3.10.

test.support.check_disallow_instantiation(test_case, tp, *args, **kwds)

   Assert that type *tp* cannot be instantiated using *args* and
   *kwds*.

   Added in version 3.10.

test.support.adjust_int_max_str_digits(max_digits)

   This function returns a context manager that will change the global
   "sys.set_int_max_str_digits()" setting for the duration of the
   context to allow execution of test code that needs a different
   limit on the number of digits when converting between an integer
   and string.

   Added in version 3.11.

The "test.support" module defines the following classes:

class test.support.SuppressCrashReport

   A context manager used to try to prevent crash dialog popups on
   tests that are expected to crash a subprocess.

   On Windows, it disables Windows Error Reporting dialogs using
   SetErrorMode.

   On UNIX, "resource.setrlimit()" is used to set
   "resource.RLIMIT_CORE"'s soft limit to 0 to prevent coredump file
   creation.

   On both platforms, the old value is restored by "__exit__()".

class test.support.SaveSignals

   Class to save and restore signal handlers registered by the Python
   signal handler.

   save(self)

      Save the signal handlers to a dictionary mapping signal numbers
      to the current signal handler.

   restore(self)

      Set the signal numbers from the "save()" dictionary to the saved
      handler.

class test.support.Matcher

   matches(self, d, **kwargs)

      Try to match a single dict with the supplied arguments.

   match_value(self, k, dv, v)

      Try to match a single stored value (*dv*) with a supplied value
      (*v*).


"test.support.socket_helper" --- Utilities for socket tests
***********************************************************

The "test.support.socket_helper" module provides support for socket
tests.

Added in version 3.9.

test.support.socket_helper.IPV6_ENABLED

   Set to "True" if IPv6 is enabled on this host, "False" otherwise.

test.support.socket_helper.find_unused_port(family=socket.AF_INET, socktype=socket.SOCK_STREAM)

   Returns an unused port that should be suitable for binding.  This
   is achieved by creating a temporary socket with the same family and
   type as the "sock" parameter (default is "AF_INET", "SOCK_STREAM"),
   and binding it to the specified host address (defaults to
   "0.0.0.0") with the port set to 0, eliciting an unused ephemeral
   port from the OS. The temporary socket is then closed and deleted,
   and the ephemeral port is returned.

   Either this method or "bind_port()" should be used for any tests
   where a server socket needs to be bound to a particular port for
   the duration of the test. Which one to use depends on whether the
   calling code is creating a Python socket, or if an unused port
   needs to be provided in a constructor or passed to an external
   program (i.e. the "-accept" argument to openssl's s_server mode).
   Always prefer "bind_port()" over "find_unused_port()" where
   possible.  Using a hard coded port is discouraged since it can make
   multiple instances of the test impossible to run simultaneously,
   which is a problem for buildbots.

test.support.socket_helper.bind_port(sock, host=HOST)

   Bind the socket to a free port and return the port number.  Relies
   on ephemeral ports in order to ensure we are using an unbound port.
   This is important as many tests may be running simultaneously,
   especially in a buildbot environment.  This method raises an
   exception if the "sock.family" is "AF_INET" and "sock.type" is
   "SOCK_STREAM", and the socket has "SO_REUSEADDR" or "SO_REUSEPORT"
   set on it. Tests should never set these socket options for TCP/IP
   sockets. The only case for setting these options is testing
   multicasting via multiple UDP sockets.

   Additionally, if the "SO_EXCLUSIVEADDRUSE" socket option is
   available (i.e. on Windows), it will be set on the socket.  This
   will prevent anyone else from binding to our host/port for the
   duration of the test.

test.support.socket_helper.bind_unix_socket(sock, addr)

   Bind a Unix socket, raising "unittest.SkipTest" if
   "PermissionError" is raised.

@test.support.socket_helper.skip_unless_bind_unix_socket

   A decorator for running tests that require a functional "bind()"
   for Unix sockets.

test.support.socket_helper.transient_internet(resource_name, *, timeout=30.0, errnos=())

   A context manager that raises "ResourceDenied" when various issues
   with the internet connection manifest themselves as exceptions.


"test.support.script_helper" --- Utilities for the Python execution tests
*************************************************************************

The "test.support.script_helper" module provides support for Python's
script execution tests.

test.support.script_helper.interpreter_requires_environment()

   Return "True" if "sys.executable interpreter" requires environment
   variables in order to be able to run at all.

   This is designed to be used with "@unittest.skipIf()" to annotate
   tests that need to use an "assert_python*()" function to launch an
   isolated mode ("-I") or no environment mode ("-E") sub-interpreter
   process.

   A normal build & test does not run into this situation but it can
   happen when trying to run the standard library test suite from an
   interpreter that doesn't have an obvious home with Python's current
   home finding logic.

   Setting "PYTHONHOME" is one way to get most of the testsuite to run
   in that situation.  "PYTHONPATH" or "PYTHONUSERSITE" are other
   common environment variables that might impact whether or not the
   interpreter can start.

test.support.script_helper.run_python_until_end(*args, **env_vars)

   Set up the environment based on *env_vars* for running the
   interpreter in a subprocess.  The values can include "__isolated",
   "__cleanenv", "__cwd", and "TERM".

   バージョン 3.9 で変更: The function no longer strips whitespaces
   from *stderr*.

test.support.script_helper.assert_python_ok(*args, **env_vars)

   Assert that running the interpreter with *args* and optional
   environment variables *env_vars* succeeds ("rc == 0") and return a
   "(return code, stdout, stderr)" tuple.

   If the *__cleanenv* keyword-only parameter is set, *env_vars* is
   used as a fresh environment.

   Python is started in isolated mode (command line option "-I"),
   except if the *__isolated* keyword-only parameter is set to
   "False".

   バージョン 3.9 で変更: The function no longer strips whitespaces
   from *stderr*.

test.support.script_helper.assert_python_failure(*args, **env_vars)

   Assert that running the interpreter with *args* and optional
   environment variables *env_vars* fails ("rc != 0") and return a
   "(return code, stdout, stderr)" tuple.

   See "assert_python_ok()" for more options.

   バージョン 3.9 で変更: The function no longer strips whitespaces
   from *stderr*.

test.support.script_helper.spawn_python(*args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, **kw)

   Run a Python subprocess with the given arguments.

   *kw* is extra keyword args to pass to "subprocess.Popen()". Returns
   a "subprocess.Popen" object.

test.support.script_helper.kill_python(p)

   Run the given "subprocess.Popen" process until completion and
   return stdout.

test.support.script_helper.make_script(script_dir, script_basename, source, omit_suffix=False)

   Create script containing *source* in path *script_dir* and
   *script_basename*. If *omit_suffix* is "False", append ".py" to the
   name.  Return the full script path.

test.support.script_helper.make_zip_script(zip_dir, zip_basename, script_name, name_in_zip=None)

   Create zip file at *zip_dir* and *zip_basename* with extension
   "zip" which contains the files in *script_name*. *name_in_zip* is
   the archive name. Return a tuple containing "(full path, full path
   of archive name)".

test.support.script_helper.make_pkg(pkg_dir, init_source='')

   Create a directory named *pkg_dir* containing an "__init__" file
   with *init_source* as its contents.

test.support.script_helper.make_zip_pkg(zip_dir, zip_basename, pkg_name, script_basename, source, depth=1, compiled=False)

   Create a zip package directory with a path of *zip_dir* and
   *zip_basename* containing an empty "__init__" file and a file
   *script_basename* containing the *source*.  If *compiled* is
   "True", both source files will be compiled and added to the zip
   package.  Return a tuple of the full zip path and the archive name
   for the zip file.


"test.support.bytecode_helper" --- Support tools for testing correct bytecode generation
****************************************************************************************

The "test.support.bytecode_helper" module provides support for testing
and inspecting bytecode generation.

Added in version 3.9.

The module defines the following class:

class test.support.bytecode_helper.BytecodeTestCase(unittest.TestCase)

   This class has custom assertion methods for inspecting bytecode.

BytecodeTestCase.get_disassembly_as_string(co)

   Return the disassembly of *co* as string.

BytecodeTestCase.assertInBytecode(x, opname, argval=_UNSPECIFIED)

   Return instr if *opname* is found, otherwise throws
   "AssertionError".

BytecodeTestCase.assertNotInBytecode(x, opname, argval=_UNSPECIFIED)

   Throws "AssertionError" if *opname* is found.


"test.support.threading_helper" --- Utilities for threading tests
*****************************************************************

The "test.support.threading_helper" module provides support for
threading tests.

Added in version 3.10.

test.support.threading_helper.join_thread(thread, timeout=None)

   Join a *thread* within *timeout*.  Raise an "AssertionError" if
   thread is still alive after *timeout* seconds.

@test.support.threading_helper.reap_threads

   Decorator to ensure the threads are cleaned up even if the test
   fails.

test.support.threading_helper.start_threads(threads, unlock=None)

   Context manager to start *threads*, which is a sequence of threads.
   *unlock* is a function called after the threads are started, even
   if an exception was raised; an example would be
   "threading.Event.set()". "start_threads" will attempt to join the
   started threads upon exit.

test.support.threading_helper.threading_cleanup(*original_values)

   Cleanup up threads not specified in *original_values*.  Designed to
   emit a warning if a test leaves running threads in the background.

test.support.threading_helper.threading_setup()

   Return current thread count and copy of dangling threads.

test.support.threading_helper.wait_threads_exit(timeout=None)

   Context manager to wait until all threads created in the "with"
   statement exit.

test.support.threading_helper.catch_threading_exception()

   Context manager catching "threading.Thread" exception using
   "threading.excepthook()".

   Attributes set when an exception is caught:

   * "exc_type"

   * "exc_value"

   * "exc_traceback"

   * "thread"

   See "threading.excepthook()" documentation.

   These attributes are deleted at the context manager exit.

   使い方:

      with threading_helper.catch_threading_exception() as cm:
          # code spawning a thread which raises an exception
          ...

          # check the thread exception, use cm attributes:
          # exc_type, exc_value, exc_traceback, thread
          ...

      # exc_type, exc_value, exc_traceback, thread attributes of cm no longer
      # exists at this point
      # (to avoid reference cycles)

   Added in version 3.8.

test.support.threading_helper.run_concurrently(worker_func, nthreads, args=(), kwargs={})

   Run the worker function concurrently in multiple threads. Re-raises
   an exception if any thread raises one, after all threads have
   finished.


"test.support.os_helper" --- Utilities for os tests
***************************************************

The "test.support.os_helper" module provides support for os tests.

Added in version 3.10.

test.support.os_helper.FS_NONASCII

   "os.fsencode()" でエンコードできる 非 ASCII 文字。

test.support.os_helper.SAVEDCWD

   "os.getcwd()" に設定されます。

test.support.os_helper.TESTFN

   テンポラリファイルの名前として安全に利用できる名前に設定されます。
   作成した一時ファイルは全て閉じ、unlink (削除) しなければなりません
   。

test.support.os_helper.TESTFN_NONASCII

   Set to a filename containing the "FS_NONASCII" character, if it
   exists. This guarantees that if the filename exists, it can be
   encoded and decoded with the default filesystem encoding. This
   allows tests that require a non-ASCII filename to be easily skipped
   on platforms where they can't work.

test.support.os_helper.TESTFN_UNENCODABLE

   strictモードのファイルシステムエンコーディングでエンコードできない
   ファイル名（str型）に設定します。そのようなファイル名を生成できない
   場合は、 "None" になる可能性があります。

test.support.os_helper.TESTFN_UNDECODABLE

   strictモードのファイルシステムエンコーディングでデコードできないフ
   ァイル名（bytes型）に設定します。そのようなファイル名を生成できない
   場合は、 "None" になる可能性があります。

test.support.os_helper.TESTFN_UNICODE

   非 ASCII 名を一時ファイルに設定します。

class test.support.os_helper.EnvironmentVarGuard

   一時的に環境変数をセット・アンセットするためのクラスです。このクラ
   スのインスタンスはコンテキストマネージャーとして利用されます。また
   、 "os.environ" に対する参照・更新を行う完全な辞書のインターフェー
   スを持ちます。コンテキストマネージャーが終了した時、このインスタン
   ス経由で環境変数へ行った全ての変更はロールバックされます。

   バージョン 3.1 で変更: 辞書のインターフェースを追加しました。

class test.support.os_helper.FakePath(path)

   Simple *path-like object*.  It implements the "__fspath__()" method
   which just returns the *path* argument.  If *path* is an exception,
   it will be raised in "__fspath__()".

EnvironmentVarGuard.set(envvar, value)

   一時的に、 "envvar" を "value" にセットします。

EnvironmentVarGuard.unset(envvar, *others)

   Temporarily unset one or more environment variables.

   バージョン 3.14 で変更: More than one environment variable can be
   unset.

test.support.os_helper.can_symlink()

   OS がシンボリックリンクをサポートする場合 "True" を返し、その他の場
   合は "False" を返します。

test.support.os_helper.can_xattr()

   Return "True" if the OS supports xattr, "False" otherwise.

test.support.os_helper.change_cwd(path, quiet=False)

   カレントディレクトリを一時的に *path* に変更し与えるコンテキストマ
   ネージャです。

   *quiet* が "False" の場合、コンテキストマネージャはエラーが起きると
   例外を送出します。 それ以外の場合には、警告を出すだけでカレントディ
   レクトリは同じままにしておきます。

test.support.os_helper.create_empty_file(filename)

   Create an empty file with *filename*.  If it already exists,
   truncate it.

test.support.os_helper.fd_count()

   Count the number of open file descriptors.

test.support.os_helper.fs_is_case_insensitive(directory)

   Return "True" if the file system for *directory* is case-
   insensitive.

test.support.os_helper.make_bad_fd()

   一時ファイルを開いた後に閉じ、そのファイル記述子を返すことで無効な
   記述子を作成します。

test.support.os_helper.rmdir(filename)

   Call "os.rmdir()" on *filename*.  On Windows platforms, this is
   wrapped with a wait loop that checks for the existence of the file,
   which is needed due to antivirus programs that can hold files open
   and prevent deletion.

test.support.os_helper.rmtree(path)

   Call "shutil.rmtree()" on *path* or call "os.lstat()" and
   "os.rmdir()" to remove a path and its contents.  As with "rmdir()",
   on Windows platforms this is wrapped with a wait loop that checks
   for the existence of the files.

@test.support.os_helper.skip_unless_symlink

   シンボリックリンクのサポートが必要なテストを実行することを表すデコ
   レータ。

@test.support.os_helper.skip_unless_xattr

   A decorator for running tests that require support for xattr.

test.support.os_helper.temp_cwd(name='tempcwd', quiet=False)

   一時的に新しいディレクトリを作成し、カレントディレクトリ (current
   working directory, CWD) を変更するコンテキストマネージャです。

   一時的にカレントディレクトリを変更する前に、カレントディレクトリに
   *name* という名前のディレクトリを作成します。 *name* が "None" の場
   合は、一時ディレクトリは "tempfile.mkdtemp()" を使って作成されます
   。

   *quiet* が "False" でカレントディレクトリの作成や変更ができない場合
   、例外を送出します。 それ以外の場合には、警告を出すだけで元のカレン
   トディレクトリが使われます。

test.support.os_helper.temp_dir(path=None, quiet=False)

   *path* に一時ディレクトリを作成し与えるコンテキストマネージャです。

   If *path* is "None", the temporary directory is created using
   "tempfile.mkdtemp()".  If *quiet* is "False", the context manager
   raises an exception on error.  Otherwise, if *path* is specified
   and cannot be created, only a warning is issued.

test.support.os_helper.temp_umask(umask)

   一時的にプロセスの umask を設定するコンテキストマネージャ。

test.support.os_helper.unlink(filename)

   Call "os.unlink()" on *filename*.  As with "rmdir()", on Windows
   platforms, this is wrapped with a wait loop that checks for the
   existence of the file.


"test.support.import_helper" --- Utilities for import tests
***********************************************************

The "test.support.import_helper" module provides support for import
tests.

Added in version 3.10.

test.support.import_helper.forget(module_name)

   モジュール名 *module_name* を "sys.modules" から取り除き、モジュー
   ルのバイトコンパイル済みファイルを全て削除します。

test.support.import_helper.import_fresh_module(name, fresh=(), blocked=(), deprecated=False)

   この関数は、 *name* で指定された Python モジュールを、インポート前
   に "sys.modules" から削除することで新規にインポートしてそのコピーを
   返します。 "reload()" 関数と違い、もとのモジュールはこの操作によっ
   て影響をうけません。

   *fresh* は、同じようにインポート前に "sys.modules" から削除されるモ
   ジュール名の iterable です。

   *blocked* もモジュール名のイテラブルで、インポート中にモジュールキ
   ャッシュ内でその名前を "None" に置き換えることで、そのモジュールを
   インポートしようとすると "ImportError" を発生させます。

   指定されたモジュールと *fresh* や *blocked* 引数内のモジュール名は
   インポート前に保存され、フレッシュなインポートが完了したら
   "sys.modules" に戻されます。

   *deprecated* が "True" の場合、インポート中はモジュールとパッケージ
   の廃止メッセージが抑制されます。

   指定したモジュールがインポートできなかった場合に、この関数は
   "ImportError" を送出します。

   使用例:

      # Get copies of the warnings module for testing without affecting the
      # version being used by the rest of the test suite. One copy uses the
      # C implementation, the other is forced to use the pure Python fallback
      # implementation
      py_warnings = import_fresh_module('warnings', blocked=['_warnings'])
      c_warnings = import_fresh_module('warnings', fresh=['_warnings'])

   Added in version 3.1.

test.support.import_helper.import_module(name, deprecated=False, *, required_on=())

   この関数は *name* で指定されたモジュールをインポートして返します。
   通常のインポートと異なり、この関数はモジュールをインポートできなか
   った場合に "unittest.SkipTest" 例外を発生させます。

   Module and package deprecation messages are suppressed during this
   import if *deprecated* is "True".  If a module is required on a
   platform but optional for others, set *required_on* to an iterable
   of platform prefixes which will be compared against "sys.platform".

   Added in version 3.1.

test.support.import_helper.modules_setup()

   Return a copy of "sys.modules".

test.support.import_helper.modules_cleanup(oldmodules)

   Remove modules except for *oldmodules* and "encodings" in order to
   preserve internal cache.

test.support.import_helper.unload(name)

   "sys.modules" から *name* を削除します。

test.support.import_helper.make_legacy_pyc(source)

   Move a **PEP 3147**/**PEP 488** pyc file to its legacy pyc location
   and return the file system path to the legacy pyc file.  The
   *source* value is the file system path to the source file.  It does
   not need to exist, however the PEP 3147/488 pyc file must exist.

class test.support.import_helper.CleanImport(*module_names)

   A context manager to force import to return a new module reference.
   This is useful for testing module-level behaviors, such as the
   emission of a "DeprecationWarning" on import.  Example usage:

      with CleanImport('foo'):
          importlib.import_module('foo')  # New reference.

class test.support.import_helper.DirsOnSysPath(*paths)

   A context manager to temporarily add directories to "sys.path".

   This makes a copy of "sys.path", appends any directories given as
   positional arguments, then reverts "sys.path" to the copied
   settings when the context ends.

   Note that *all* "sys.path" modifications in the body of the context
   manager, including replacement of the object, will be reverted at
   the end of the block.


"test.support.warnings_helper" --- Utilities for warnings tests
***************************************************************

The "test.support.warnings_helper" module provides support for
warnings tests.

Added in version 3.10.

test.support.warnings_helper.ignore_warnings(*, category)

   Suppress warnings that are instances of *category*, which must be
   "Warning" or a subclass. Roughly equivalent to
   "warnings.catch_warnings()" with "warnings.simplefilter('ignore',
   category=category)". For example:

      @warning_helper.ignore_warnings(category=DeprecationWarning)
      def test_suppress_warning():
          # do something

   Added in version 3.8.

test.support.warnings_helper.check_no_resource_warning(testcase)

   Context manager to check that no "ResourceWarning" was raised.  You
   must remove the object which may emit "ResourceWarning" before the
   end of the context manager.

test.support.warnings_helper.check_syntax_warning(testcase, statement, errtext='', *, lineno=1, offset=None)

   Test for syntax warning in *statement* by attempting to compile
   *statement*. Test also that the "SyntaxWarning" is emitted only
   once, and that it will be converted to a "SyntaxError" when turned
   into error. *testcase* is the "unittest" instance for the test.
   *errtext* is the regular expression which should match the string
   representation of the emitted "SyntaxWarning" and raised
   "SyntaxError".  If *lineno* is not "None", compares to the line of
   the warning and exception. If *offset* is not "None", compares to
   the offset of the exception.

   Added in version 3.8.

test.support.warnings_helper.check_warnings(*filters, quiet=True)

   A convenience wrapper for "warnings.catch_warnings()" that makes it
   easier to test that a warning was correctly raised.  It is
   approximately equivalent to calling
   "warnings.catch_warnings(record=True)" with
   "warnings.simplefilter()" set to "always" and with the option to
   automatically validate the results that are recorded.

   "check_warnings" は "("message regexp", WarningCategory)" の形をし
   た 2要素タプルを位置引数として受け取ります。1つ以上の *filters* が
   与えられた場合や、オプションのキーワード引数 *quiet* が "False" の
   場合、警告が期待通りであるかどうかをチェックします。指定された各
   filter は最低でも1回は囲われたコード内で発生した警告とマッチしなけ
   ればテストが失敗しますし、指定されたどの filter ともマッチしない警
   告が発生してもテストが失敗します。前者のチェックを無効にするには、
   *quiet* を "True" にします。

   引数が1つもない場合、デフォルトでは次のようになります:

      check_warnings(("", Warning), quiet=True)

   この場合、全ての警告は補足され、エラーは発生しません。

   コンテキストマネージャーに入る時、 "WarningRecorder" インスタンスが
   返されます。このレコーダーオブジェクトの "warnings" 属性から、
   "catch_warnings()" から得られる警告のリストを取得することができます
   。便利さのために、レコーダーオブジェクトから直接、一番最近に発生し
   た警告を表すオブジェクトの属性にアクセスできます(以下にある例を参照
   してください)。警告が1つも発生しなかった場合、それらの全ての属性は
   "None" を返します。

   レコーダーオブジェクトの "reset()" メソッドは警告リストをクリアしま
   す。

   コンテキストマネージャーは次のようにして使います:

      with check_warnings(("assertion is always true", SyntaxWarning),
                          ("", UserWarning)):
          exec('assert(False, "Hey!")')
          warnings.warn(UserWarning("Hide me!"))

   この場合、どちらの警告も発生しなかった場合や、それ以外の警告が発生
   した場合は、 "check_warnings()" はエラーを発生させます。

   警告が発生したかどうかだけでなく、もっと詳しいチェックが必要な場合
   は、次のようなコードになります:

      with check_warnings(quiet=True) as w:
          warnings.warn("foo")
          assert str(w.args[0]) == "foo"
          warnings.warn("bar")
          assert str(w.args[0]) == "bar"
          assert str(w.warnings[0].args[0]) == "foo"
          assert str(w.warnings[1].args[0]) == "bar"
          w.reset()
          assert len(w.warnings) == 0

   全ての警告をキャプチャし、テストコードがその警告を直接テストします
   。

   バージョン 3.2 で変更: 新しいオプション引数 *filters* と *quiet*

class test.support.warnings_helper.WarningsRecorder

   ユニットテスト時に warning を記録するためのクラスです。上の、
   "check_warnings()" のドキュメントを参照してください。
