Method isolation

src/click/testing.py:399–594

A context manager that sets up the isolation for invoking of a command line tool. This sets up `<stdin>` with the given input data and `os.environ` with the overrides from the given dictionary. This also rebinds some internals in Click to be mocked (like the prompt f

(
        self,
        input: str | bytes | t.IO[t.Any] | None = None,
        env: cabc.Mapping[str, str | None] | None = None,
        color: bool = False,
    )

    @contextlib.contextmanager
    def isolation(
        self,
        input: str | bytes | t.IO[t.Any] | None = None,
        env: cabc.Mapping[str, str | None] | None = None,
        color: bool = False,
    ) -> cabc.Generator[tuple[io.BytesIO, io.BytesIO, io.BytesIO]]:
        class="st">"""A context manager that sets up the isolation for invoking of a
        command line tool.  This sets up `<stdin>` with the given input data
        and `os.environ` with the overrides from the given dictionary.
        This also rebinds some internals in Click to be mocked (like the
        prompt functionality).

        This is automatically done in the :meth:`invoke` method.

        :param input: the input stream to put into `sys.stdin`.
        :param env: the environment overrides as dictionary.
        :param color: whether the output should contain color codes. The
                      application can still override this explicitly.

        .. versionadded:: 8.2
            An additional output stream is returned, which is a mix of
            `<stdout>` and `<stderr>` streams.

        .. versionchanged:: 8.2
            Always returns the `<stderr>` stream.

        .. versionchanged:: 8.0
            `<stderr>` is opened with ``errors=class="st">"backslashreplace"``
            instead of the default ``class="st">"strict"``.

        .. versionchanged:: 4.0
            Added the ``color`` parameter.
        class="st">"""
        bytes_input = make_input_stream(input, self.charset)
        echo_input = None

        old_stdin = sys.stdin
        old_stdout = sys.stdout
        old_stderr = sys.stderr
        old_forced_width = formatting.FORCED_WIDTH
        formatting.FORCED_WIDTH = 80

        env = self.make_env(env)

        stream_mixer = StreamMixer()

        if self.echo_stdin:
            bytes_input = echo_input = t.cast(
                t.BinaryIO, EchoingStdin(bytes_input, stream_mixer.stdout)
            )

        sys.stdin = text_input = _NamedTextIOWrapper(
            bytes_input, encoding=self.charset, name=class="st">"<stdin>", mode=class="st">"r"
        )

        if self.echo_stdin:
            class="cm"># Force unbuffered reads, otherwise TextIOWrapper reads a
            class="cm"># large chunk which is echoed early.