[Python-3000] TextIOWrapper.write(s:str) and bytes in py3k-struni

[Christian Heimes]

Hello!

I'm having some troubles with unit tests in the py3k-struni branch. Some
test like test_uu are failing because an io.TextIOWrapper instance's
write() method doesn't handle bytes. The method is defined as:

    def write(self, s: str):
        if self.closed:
            raise ValueError("write to closed file")
        # XXX What if we were just reading?
        b = s.encode(self._encoding)
        if isinstance(b, str):
            b = bytes(b)
        n = self.buffer.write(b)
        if "\n" in s:
            # XXX only if isatty
            self.flush()
        self._snapshot = self._decoder = None
        return len(s)

The problematic lines are the lines from s.encode() to b = bytes(b). The
behavior is more than questionable. A bytes object doesn't have an
encode() method and str's encode method() always returns bytes. IMO the
write() method should be changed to:

    def write(self, s: (str, bytes)):
        if self.closed:
            raise ValueError("write to closed file")
        # XXX What if we were just reading?
        if isinstance(s, basestring):
            b = s.encode(self._encoding)
        elif isinstance(s, bytes):
            b = s
        else:
            b = bytes(b)
        n = self.buffer.write(b)
        if b"\n" in b:
            # XXX only if isatty
            self.flush()
        self._snapshot = self._decoder = None
        return len(s)

Or the write() should explictly raise a TypeError when it is not allowed
to handle bytes.

Christian