# `test` — Regression tests package for Python

Nota

O pacote `test` é apenas para uso interno do Python. O mesmo está sendo documentado para o benefício dos principais desenvolvedores do Python. Qualquer uso deste pacote fora da biblioteca padrão do Python é desencorajado, pois, o código mencionado aqui pode ser alterado ou removido sem aviso prévio entre as versões do Python.

O pacote `test` contém todos os testes de regressão do Python, bem como os módulos `test.support` e `test.regrtest`. `test.support` é utilizado para aprimorar seus testes enquanto o `test.regrtest` direciona a suite de testes.

Cada módulo no pacote `test` cujo nome começa com `test_` é um conjunto de testes para um módulo ou recurso específico. Todos os novos testes devem ser escritos usando o módulo `unittest` ou `doctest`. Alguns testes mais antigos são escritos usando um estilo de teste “tradicional” que compara a saída impressa a `sys.stdout`. Este estilo de teste foi considerado descontinuado.

Ver também

Módulo `unittest`

  Escrevendo testes de regressão PyUnit.

Módulo `doctest`

  Testes embutidos em Strings da documentação.

## Escrever testes unitários para o pacote `test`

É preferível que os testes que usam o módulo `unittest` sigam algumas diretrizes. Uma é nomear o módulo de teste iniciando-o com `test_` e termine com o nome do módulo que está sendo testado. Os métodos de teste no módulo de teste deve começar com `test_` e terminar com uma descrição do que o método está testando. Isso é necessário para que os métodos sejam reconhecidos pelo driver de teste como métodos de teste. Além disso, na string de documentação para o método deve ser incluído. Um comentário (como os `# Tests function returns only True or False`) deve ser usado para fornecer documentação para testar métodos. Isso é feito porque as strings de documentação são impressas se existem e, portanto, qual teste está sendo executado não é indicado.

Um boilerplate básico é muitas vezes usado:

    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()

Este padrão de código permite que o conjunto de testes seja executado pelo `test.regrtest`, por conta própria, como um script que suporte o `unittest` CLI, ou através do `python -m unittest` CLI.

O objetivo do teste de regressão é tentar quebrar o código. Isso leva a algumas diretrizes que devemos seguir:

- O conjunto de testes deve exercitar todas as classes, funções e constantes. Isso inclui não apenas a API externa que deve ser apresentada ao mundo exterior, mas também o código “privado”.

- Os testes de Whitebox (que examinam o código que está sendo testado quando os testes estão sendo gravados) são preferidos. O teste Blackbox (que testa apenas a interface do público de usuário) não é completo o suficiente para garantir que todos os casos de limite e extremos sejam testados.

- Certifique-se de que todos os valores possíveis sejam testados, incluindo os inválidos. Isso garante que não apenas todos os valores válidos são aceitos, mas também, que os valores impróprios são tratados corretamente.

- Esgote o maior número possível de caminhos de código. Teste onde ocorre a ramificação e, assim, personalize a entrada para garantir que tantos caminhos diferentes pelo código sejam tomados.

- Adicione um teste explícito para quaisquer bugs descobertos ao código testado. Isso garantirá que o erro não apareça novamente se o código for alterado no futuro.

- Certifique-se de limpar após seus testes (como fechar e remover todos os arquivos temporários).

- Se um teste depende de uma condição específica do sistema operacional, então verifica se a condição já existe antes de tentar o teste.

- Importa o menor número de módulos possível e faça isso o mais rápido possível. Isso minimiza dependências externas de testes, e também minimiza possíveis comportamento anômalo dos efeitos colaterais da importação de um módulo.

- Tente maximizar a reutilização de código. Ocasionalmente, os testes variam em algo tão pequeno quanto o tipo de entrada é usado. Minimize a duplicação de código criando uma subclasse básica de testes com uma classe que especifica o input:

      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`.

Ver também

Test Driven Development

  Um livro de Kent Beck sobre escrita de testes antes do código.

## Executando testes usando a interface de linha de comando

O pacote `test` pode ser executado como um script para conduzir o conjunto de testes de regressão do Python, graças à opção `-m`: python -m test. Nos bastidores, ele usa `test.regrtest`; a chamada python -m test.regrtest usado nas versões anteriores do Python ainda funciona. Executar o script por si só começa a executar todos os testes de regressão no pacote `test`. Ele faz isso encontrando todos os módulos no pacote cujo nome começa com `test_`, importando-os e executando a função `test_main()` se presente ou carregando os testes via unittest.TestLoader.loadTestsFromModule se `test_main` não existir. Os nomes dos testes a serem executados também podem ser passados para o script. Especificando um teste de regressão simples (python -m test test_spam) minimizará saiba e imprima apenas se o teste passou ou falhou.

A execução de `test` permite definir diretamente quais recursos estão disponíveis para os testes usarem. Você faz isso usando a opção de linha de comando `-u`. Especificar `all` como o valor para a opção `-u` ativa todos os recursos possíveis: python -m test -uall. Se todos menos um recurso for desejado (um caso mais comum), uma lista separada por vírgulas de recursos que não são desejados pode ser listada após `all`. O comando python -m test -uall,-audio,-largefile executará `test` com todos os recursos, exceto os recursos `audio` e `largefile`. Para obter uma lista de todos os recursos e mais opções de linha de comando, execute python -m test -h.

Alguns outros meios para executar os testes de regressão dependem em qual plataforma os testes estão sendo executados. No Unix, você pode executar: programa: ‘ make test’ no diretório de mais alto nível onde o Python foi construído. No Windows, executar: programa ‘rt.bat’ do seu diretório: file: ‘PCbuild’ executará todos os testes de regressão.

# `test.support` — Utilitários para o conjunto de teste do Python

O módulo `test.support` fornece suporte para a suíte de testes de regressão do Python.

Nota

`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.

Esse módulo define as seguintes exceções:

exception test.support.TestFailed

  Exceção a ser levantada quando um teste falha. Isto foi descontinuado em favor dos testes baseados em `unittest` e métodos de asserção de `unittest.TestCase`.

exception test.support.ResourceDenied

  Subclasse de `unittest.SkipTest`. Levantada quando um recurso (como uma conexão de rede) não está disponível. Levantada pela função `requires()`.

O módulo `test.support` define as seguintes constantes:

test.support.verbose

  `True` quando a saída detalhada está habilitada. Deve ser verificado quando informações mais detalhadas são desejadas sobre um teste em execução. verbose é definido por `test.regrtest`.

test.support.is_jython

  `True` se o interpretador em execução for Jython.

test.support.is_android

  `True` se o sistema é Android.

test.support.unix_shell

  Caminho para o console se não estiver no Windows; por outro lado `None`

test.support.LOOPBACK_TIMEOUT

  Tempo limite em segundos para testes usando um servidor de rede escutando na interface de loopback local da rede como `127.0.0.1`.

  O tempo limite é longo o suficiente para evitar a falha do teste: leva em consideração que o cliente e o servidor podem ser executados em diferentes threads ou mesmo processos diferentes.

  O tempo limite deve ser longo o suficiente para os métodos `connect()`, `recv()` e `send()` de `socket.socket`.

  Seu valor padrão é 5 segundos.

  Veja também `INTERNET_TIMEOUT`.

test.support.INTERNET_TIMEOUT

  Tempo limite em segundos para solicitações de rede indo para a Internet.

  O tempo limite é curto o suficiente para evitar que um teste espere muito tempo se a requisição da Internet for bloqueada por qualquer motivo.

  Normalmente, um tempo limite usando `INTERNET_TIMEOUT` não deve marcar um teste como falhado, mas ignorá-lo: veja `transient_internet()`.

  Seu valor padrão é 1 minuto.

  Veja também `LOOPBACK_TIMEOUT`.

test.support.SHORT_TIMEOUT

  Tempo limite em segundos para marcar um teste como falho se o teste demorar “muito tempo”.

  O valor do tempo limite depende da opção da linha de comando regrtest `--timeout`.

  Se um teste usando `SHORT_TIMEOUT` começar a falhar aleatoriamente em buildbots lentos, use `LONG_TIMEOUT`.

  Seu valor padrão é 30 segundos.

test.support.LONG_TIMEOUT

  Tempo limite em segundos para detectar quando um teste trava.

  É longo o suficiente para reduzir o risco de falha de teste nos buildbots Python mais lentos. Não deve ser usado para marcar um teste como reprovado se o teste demorar “muito tempo”. O valor do tempo limite depende da opção de linha de comando regrtest `--timeout`.

  Seu valor padrão é 5 minutos.

  Veja também `LOOPBACK_TIMEOUT`, `INTERNET_TIMEOUT` e `SHORT_TIMEOUT`.

test.support.PGO

  Definido quando os testes podem ser ignorados quando não são úteis para PGO.

test.support.PIPE_MAX_SIZE

  Uma constante que provavelmente é maior que o tamanho do buffer de canal do sistema operacional subjacente, para fazer o bloqueio de escritas.

test.support.Py_DEBUG

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

  Adicionado na versão 3.12.

test.support.SOCK_MAX_SIZE

  Uma constante que provavelmente é maior que o tamanho do buffer de soquete do sistema operacional subjacente, para fazer o bloqueio de escritas.

test.support.TEST_SUPPORT_DIR

  Define o diretório de mais alto nível que contém `test.support`.

test.support.TEST_HOME_DIR

  Define o diretório de mais alto nível para o pacote de teste.

test.support.TEST_DATA_DIR

  Set to the `data` directory within the test package.

test.support.MAX_Py_ssize_t

  Define `sys.maxsize` para grandes testes de memória.

test.support.max_memuse

  Set by `set_memlimit()` as the memory limit for big memory tests. Limited by `MAX_Py_ssize_t`.

test.support.real_max_memuse

  Set by `set_memlimit()` as the memory limit for big memory tests. Not limited by `MAX_Py_ssize_t`.

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

  Define the URL of a dedicated HTTP server for the network tests.

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.

O módulo `test.support` define as seguintes funções:

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.

  Exemplo:

      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)

  Return `True` if resource is enabled and available. The list of available resources is only set when `test.regrtest` is executing the tests.

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)

  Raise `ResourceDenied` if resource is not available. msg is the argument to `ResourceDenied` if it is raised. Always returns `True` if called by a function whose `__name__` is `'__main__'`. Used when tests are executed by `test.regrtest`.

test.support.sortdict(dict)

  Return a repr of dict with keys sorted.

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

  Return the path to the file named filename. If no match is found filename is returned. This does not equal a failure since it could be the path to the file.

  Setting subdir indicates a relative path to use to find the file rather than looking directly in the path directories.

test.support.get_pagesize()

  Get size of a page in bytes.

  Adicionado na versão 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)

  Define os valores para `max_memuse` e `real_max_memuse` para grandes testes de memória.

test.support.record_original_stdout(stdout)

  Armazena o valor de stdout. Destina-se a manter o stdout no momento em que o registro começou.

test.support.get_original_stdout()

  Retorna o stdout original definido por `record_original_stdout()` ou `sys.stdout` se não estiver definido.

test.support.args_from_interpreter_flags()

  Retorna uma lista de argumentos de linha de comando reproduzindo as configurações em `sys.flags` e `sys.warnoptions`.

test.support.optim_args_from_interpreter_flags()

  Retorna a lista de argumentos da linha de comando reproduzindo as configurações de otimização atuais em `sys.flags`.

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

  Um gerenciador de contexto que substitui temporariamente o fluxo nomeado pelo objeto `io.StringIO`.

  Exemplo do uso com fluxos de saída:

      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"

  Exemplo de uso com fluxo de entrada:

      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()

  Um gerenciador de contexto que desativa temporariamente `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.

  Uso:

      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.

  Uso:

      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.

  Adicionado na versão 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.

  Adicionado na versão 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.

  Adicionado na versão 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)

  A decorator to conditionally mark tests with `unittest.expectedFailure()`. Any use of this decorator should have an associated comment identifying the relevant tracker issue.

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)

  A decorator for running a function in a different locale, correctly resetting it after it has finished. catstr is the locale category as a string (for example `"LC_ALL"`). The locales passed will be tried sequentially, and the first valid locale will be used.

@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

  Decorador para pular testes na construção com threads livres. Se a GIL estiver desabilitada, o teste será ignorado.

@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.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

  Decorador para testes que preeenche o espaço do endereço.

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)

  Abre url. Se falhar em abrir, levanta `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.

  Uso:

      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)

  Adicionado na versão 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 ‘__’.

  Adicionado na versão 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.

  Exemplo de uso:

      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)

  Adicionado na versão 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`.

  Adicionado na versão 3.10.

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

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

  Adicionado na versão 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.

  Adicionado na versão 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.

  No Windows, desativa as caixas de diálogo Relatório de Erros do Windows usando SetErrorMode <https://msdn.microsoft.com/en-us/library/windows/desktop/ms680621.aspx>_.

  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)

    Tenta corresponder um único dicionário com os argumentos fornecidos.

  match_value(self, k, dv, v)

    Tente combinar um único valor armazenado (dv) com um valor fornecido (v).

# `test.support.socket_helper` — Utilities for socket tests

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

Adicionado na versão 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`.

  Alterado na versão 3.9: 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`.

  Alterado na versão 3.9: 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.

  Alterado na versão 3.9: 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)

  Cria um script contendo source no caminho script_dir e script_basename. Se omit_suffix `False`, acrescente `.py` ao nome. Retorna o caminho completo do script.

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

  Cria um arquivo zip em zip_dir e zip_basename com a extensão `zip` que contém os arquivos em script_name. name_in_zip é o nome do arquivo. Retorna uma tupla contendo `(full path, full path of archive name)`.

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

  Cria um diretório nomeado pkg_dir contendo um arquivo `__init__` com init_source como seus conteúdos.

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` — Ferramentas de suporte para testar a geração correta de bytecode

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

Adicionado na versão 3.9.

O módulo define a seguinte classe:

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.

Adicionado na versão 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.

  Uso:

      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)

  Adicionado na versão 3.8.

# `test.support.os_helper` — Utilities for os tests

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

Adicionado na versão 3.10.

test.support.os_helper.FS_NONASCII

  A non-ASCII character encodable by `os.fsencode()`.

test.support.os_helper.SAVEDCWD

  Set to `os.getcwd()`.

test.support.os_helper.TESTFN

  Set to a name that is safe to use as the name of a temporary file. Any temporary file that is created should be closed and unlinked (removed).

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

  Define o nome de arquivo (tipo str) que não pode ser codificado pela codificação do sistema de arquivos no modo estrito. Ele pode ser `None` se não for possível gerar como um nome de arquivo.

test.support.os_helper.TESTFN_UNDECODABLE

  Define o nome de arquivo (tipo str) que não pode ser codificado pela codificação do sistema de arquivos no modo estrito. Ele pode ser `None` se não for possível ser gerado com um nome de arquivo.

test.support.os_helper.TESTFN_UNICODE

  Define um nome não-ASCII para o arquivo temporário.

class test.support.os_helper.EnvironmentVarGuard

  Class used to temporarily set or unset environment variables. Instances can be used as a context manager and have a complete dictionary interface for querying/modifying the underlying `os.environ`. After exit from the context manager all changes to environment variables done through this instance will be rolled back.

  Alterado na versão 3.1: Adicionada uma interface para dicionário.

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)

  Temporariamente define a variável de ambiente `envvar` para o valor `value`.

EnvironmentVarGuard.unset(envvar)

  Desativa temporariamente a variável de ambiente `envvar`.

test.support.os_helper.can_symlink()

  Return `True` if the OS supports symbolic links, `False` otherwise.

test.support.os_helper.can_xattr()

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

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

  A context manager that temporarily changes the current working directory to path and yields the directory.

  If quiet is `False`, the context manager raises an exception on error. Otherwise, it issues only a warning and keeps the current working directory the same.

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()

  Conta o número de descritores de arquivos abertos.

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()

  Cria um descritor de arquivo inválido abrindo e fechando um arquivo temporário e retornando seu descritor.

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

  Um decorador para executar testes que requerem suporte para links simbólicos.

@test.support.os_helper.skip_unless_xattr

  Um decorador para execução de testes que requerem suporte para xattr.

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

  Um gerenciador de contexto que cria temporariamente um novo diretório e altera o diretório de trabalho atual (CWD).

  The context manager creates a temporary directory in the current directory with name name before temporarily changing the current working directory. If name is `None`, the temporary directory is created using `tempfile.mkdtemp()`.

  Se quiet é `False` e ele não possibilita criar ou alterar o CWD, um erro é levantado. Por outro lado, somente um aviso surge e o CWD original é utilizado.

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

  Um gerenciador de contexto que cria um diretório temporário no path e produz o diretório.

  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)

  Um gerenciador de contexto que temporariamente define o umask do processo.

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.

Adicionado na versão 3.10.

test.support.import_helper.forget(module_name)

  Remove the module named module_name from `sys.modules` and delete any byte-compiled files of the module.

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

  This function imports and returns a fresh copy of the named Python module by removing the named module from `sys.modules` before doing the import. Note that unlike `reload()`, the original module is not affected by this operation.

  fresh is an iterable of additional module names that are also removed from the `sys.modules` cache before doing the import.

  blocked is an iterable of module names that are replaced with `None` in the module cache during the import to ensure that attempts to import them raise `ImportError`.

  The named module and any modules named in the fresh and blocked parameters are saved before starting the import and then reinserted into `sys.modules` when the fresh import is complete.

  Module and package deprecation messages are suppressed during this import if deprecated is `True`.

  This function will raise `ImportError` if the named module cannot be imported.

  Exemplo de uso:

      # 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'])

  Adicionado na versão 3.1.

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

  This function imports and returns the named module. Unlike a normal import, this function raises `unittest.SkipTest` if the module cannot be imported.

  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`.

  Adicionado na versão 3.1.

test.support.import_helper.modules_setup()

  Retorna a cópia de `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)

  Exclui o name de `sys.modules`.

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.

Adicionado na versão 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

  Adicionado na versão 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.

  Adicionado na versão 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` accepts 2-tuples of the form `("message regexp", WarningCategory)` as positional arguments. If one or more filters are provided, or if the optional keyword argument quiet is `False`, it checks to make sure the warnings are as expected: each specified filter must match at least one of the warnings raised by the enclosed code or the test fails, and if any warnings are raised that do not match any of the specified filters the test fails. To disable the first of these checks, set quiet to `True`.

  Se nenhum argumento é especificado, o padrão é:

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

  Nesse caso, todos os avisos são capturados e nenhum erro é gerado.

  On entry to the context manager, a `WarningRecorder` instance is returned. The underlying warnings list from `catch_warnings()` is available via the recorder object’s `warnings` attribute. As a convenience, the attributes of the object representing the most recent warning can also be accessed directly through the recorder object (see example below). If no warning has been raised, then any of the attributes that would otherwise be expected on an object representing a warning will return `None`.

  The recorder object also has a `reset()` method, which clears the warnings list.

  O gerenciador de contexto é desenhado para ser utilizado dessa forma:

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

  No caso, se um aviso não foi levantado, ou algum outro aviso não foi levantado, `check_warnings()` deveria aparecer como um erro.

  When a test needs to look more deeply into the warnings, rather than just checking whether or not they occurred, code like this can be used:

      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

  Aqui todos os avisos serão capturados e o código de teste testa os avisos diretamente capturados.

  Alterado na versão 3.2: Novos argumentos opcionais filters e quiet.

class test.support.warnings_helper.WarningsRecorder

  Class used to record warnings for unit tests. See documentation of `check_warnings()` above for more details.