procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
$ testparseutil="$TESTDIR"/../contrib/testparseutil.py
Internal test by doctest
$ "$PYTHON" -m doctest "$testparseutil"
Tests for embedded python script
Typical cases
$ "$PYTHON" "$testparseutil" -v pyembedded <<NO_CHECK_EOF
> >>> for f in [1, 2, 3]:
> ... foo = 1
> >>> foo = 2
> $ echo "doctest is terminated by command, empty line, or comment"
> >>> foo = 31
> expected output of doctest fragment
> >>> foo = 32
>
> >>> foo = 33
>
> >>> foo = 34
> comment
> >>> foo = 35
>
> $ "\$PYTHON" <<EOF
> > foo = 4
> >
> > EOF
> $ cat > foo.py <<EOF
> > foo = 5
> > EOF
> $ cat >> foo.py <<EOF
> > foo = 6 # appended
> > EOF
>
> NO_CHECK_EOF limit mark makes parsing ignore corresponded fragment
> (this is useful to use bad code intentionally)
>
> $ "\$PYTHON" <<NO_CHECK_EOF
> > foo = 7 # this should be ignored at detection
> > NO_CHECK_EOF
> $ cat > foo.py <<NO_CHECK_EOF
> > foo = 8 # this should be ignored at detection
> > NO_CHECK_EOF
>
> doctest fragment ended by EOF
>
> >>> foo = 9
> NO_CHECK_EOF
<stdin>:1: <anonymous> starts
|for f in [1, 2, 3]:
| foo = 1
|foo = 2
<stdin>:4: <anonymous> ends
<stdin>:5: <anonymous> starts
|foo = 31
|
|foo = 32
|
|foo = 33
<stdin>:10: <anonymous> ends
<stdin>:11: <anonymous> starts
|foo = 34
<stdin>:12: <anonymous> ends
<stdin>:13: <anonymous> starts
|foo = 35
<stdin>:14: <anonymous> ends
<stdin>:16: <anonymous> starts
|foo = 4
|
<stdin>:18: <anonymous> ends
<stdin>:20: foo.py starts
|foo = 5
<stdin>:21: foo.py ends
<stdin>:23: foo.py starts
|foo = 6 # appended
<stdin>:24: foo.py ends
<stdin>:38: <anonymous> starts
|foo = 9
<stdin>:39: <anonymous> ends
Invalid test script
(similar test for shell script and hgrc configuration is omitted,
because this tests common base class of them)
$ "$PYTHON" "$testparseutil" -v pyembedded <<NO_CHECK_EOF > detected
> $ "\$PYTHON" <<EOF
> > foo = 1
>
> $ "\$PYTHON" <<EOF
> > foo = 2
> $ cat > bar.py <<EOF
> > bar = 2 # this fragment will be detected as expected
> > EOF
>
> $ cat > foo.py <<EOF
> > foo = 3
> NO_CHECK_EOF
<stdin>:3: unexpected line for "heredoc python invocation"
<stdin>:6: unexpected line for "heredoc python invocation"
<stdin>:11: unexpected end of file for "heredoc .py file"
[1]
$ cat detected
<stdin>:7: bar.py starts
|bar = 2 # this fragment will be detected as expected
<stdin>:8: bar.py ends
Tests for embedded shell script
$ "$PYTHON" "$testparseutil" -v shembedded <<NO_CHECK_EOF
> $ cat > foo.sh <<EOF
> > foo = 1
> >
> > foo = 2
> > EOF
> $ cat >> foo.sh <<EOF
> > foo = 3 # appended
> > EOF
>
> NO_CHECK_EOF limit mark makes parsing ignore corresponded fragment
> (this is useful to use bad code intentionally)
>
> $ cat > foo.sh <<NO_CHECK_EOF
> > # this should be ignored at detection
> > foo = 4
> > NO_CHECK_EOF
>
> NO_CHECK_EOF
<stdin>:2: foo.sh starts
|foo = 1
|
|foo = 2
<stdin>:5: foo.sh ends
<stdin>:7: foo.sh starts
|foo = 3 # appended
<stdin>:8: foo.sh ends
Tests for embedded hgrc configuration
$ "$PYTHON" "$testparseutil" -v hgrcembedded <<NO_CHECK_EOF
> $ cat > .hg/hgrc <<EOF
> > [ui]
> > verbose = true
> >
> > # end of local configuration
> > EOF
>
> $ cat > \$HGRCPATH <<EOF
> > [extensions]
> > rebase =
> > # end of global configuration
> > EOF
>
> $ cat >> \$HGRCPATH <<EOF
> > # appended
> > [extensions]
> > rebase =!
> > EOF
>
> NO_CHECK_EOF limit mark makes parsing ignore corresponded fragment
> (this is useful to use bad code intentionally)
>
> $ cat > .hg/hgrc <<NO_CHECK_EOF
> > # this local configuration should be ignored at detection
> > [ui]
> > username = foo bar
> > NO_CHECK_EOF
>
> $ cat > \$HGRCPATH <<NO_CHECK_EOF
> > # this global configuration should be ignored at detection
> > [extensions]
> > foobar =
> > NO_CHECK_EOF
> NO_CHECK_EOF
<stdin>:2: .hg/hgrc starts
|[ui]
|verbose = true
|
|# end of local configuration
<stdin>:6: .hg/hgrc ends
<stdin>:9: $HGRCPATH starts
|[extensions]
|rebase =
|# end of global configuration
<stdin>:12: $HGRCPATH ends
<stdin>:15: $HGRCPATH starts
|# appended
|[extensions]
|rebase =!
<stdin>:18: $HGRCPATH ends