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.
#require test-repo
$ . "$TESTDIR/helpers-testrepo.sh"
$ testrepohgenv
$ import_checker="$TESTDIR"/../contrib/import-checker.py
Run the doctests from the import checker, and make sure
it's working correctly.
$ TERM=dumb
$ export TERM
$ "$PYTHON" -m doctest $import_checker
Run additional tests for the import checker
$ mkdir testpackage
$ touch testpackage/__init__.py
$ cat > testpackage/multiple.py << EOF
> import os, sys
> EOF
$ cat > testpackage/unsorted.py << EOF
> import sys
> import os
> EOF
$ cat > testpackage/stdafterlocal.py << EOF
> from . import unsorted
> import os
> EOF
$ cat > testpackage/requirerelative.py << EOF
> import testpackage.unsorted
> EOF
$ cat > testpackage/importalias.py << EOF
> import ui
> EOF
$ cat > testpackage/relativestdlib.py << EOF
> from .. import os
> EOF
$ cat > testpackage/stdlibfrom.py << EOF
> from collections import abc
> EOF
$ cat > testpackage/symbolimport.py << EOF
> from .unsorted import foo
> EOF
$ cat > testpackage/latesymbolimport.py << EOF
> from . import unsorted
> from mercurial.node import hex
> EOF
$ cat > testpackage/multiplegroups.py << EOF
> from . import unsorted
> from . import more
> EOF
$ mkdir testpackage/subpackage
$ cat > testpackage/subpackage/levelpriority.py << EOF
> from . import foo
> from .. import parent
> EOF
$ touch testpackage/subpackage/foo.py
$ cat > testpackage/subpackage/__init__.py << EOF
> from . import levelpriority # should not cause cycle
> EOF
$ cat > testpackage/subpackage/localimport.py << EOF
> from . import foo
> def bar():
> # should not cause "higher-level import should come first"
> from .. import unsorted
> # but other errors should be detected
> from .. import more
> import testpackage.subpackage.levelpriority
> EOF
$ cat > testpackage/importmodulefromsub.py << EOF
> from .subpackage import foo # not a "direct symbol import"
> EOF
$ cat > testpackage/importsymbolfromsub.py << EOF
> from .subpackage import foo, nonmodule
> EOF
$ cat > testpackage/sortedentries.py << EOF
> from . import (
> foo,
> bar,
> )
> EOF
$ cat > testpackage/importfromalias.py << EOF
> from . import ui
> EOF
$ cat > testpackage/importfromrelative.py << EOF
> from testpackage.unsorted import foo
> EOF
$ mkdir testpackage2
$ touch testpackage2/__init__.py
$ cat > testpackage2/latesymbolimport.py << EOF
> from testpackage import unsorted
> from mercurial.node import hex
> EOF
# Shadowing a stdlib module to test "relative import of stdlib module" is
# allowed if the module is also being checked
$ mkdir email
$ touch email/__init__.py
$ touch email/errors.py
$ cat > email/utils.py << EOF
> from . import errors
> EOF
$ "$PYTHON" "$import_checker" testpackage*/*.py testpackage/subpackage/*.py \
> email/*.py
testpackage/importalias.py:1: ui module must be "as" aliased to uimod
testpackage/importfromalias.py:1: ui from testpackage must be "as" aliased to uimod
testpackage/importfromrelative.py:1: import should be relative: testpackage.unsorted
testpackage/importfromrelative.py:1: direct symbol import foo from testpackage.unsorted
testpackage/importsymbolfromsub.py:1: direct symbol import nonmodule from testpackage.subpackage
testpackage/latesymbolimport.py:2: symbol import follows non-symbol import: mercurial.node
testpackage/multiple.py:1: multiple imported names: os, sys
testpackage/multiplegroups.py:2: multiple "from . import" statements
testpackage/relativestdlib.py:1: relative import of stdlib module
testpackage/requirerelative.py:1: import should be relative: testpackage.unsorted
testpackage/sortedentries.py:1: imports from testpackage not lexically sorted: bar < foo
testpackage/stdafterlocal.py:2: stdlib import "os" follows local import: testpackage
testpackage/stdlibfrom.py:1: direct symbol import abc from collections
testpackage/subpackage/levelpriority.py:2: higher-level import should come first: testpackage
testpackage/subpackage/localimport.py:6: multiple "from .. import" statements
testpackage/subpackage/localimport.py:7: import should be relative: testpackage.subpackage.levelpriority
testpackage/symbolimport.py:1: direct symbol import foo from testpackage.unsorted
testpackage/unsorted.py:2: imports not lexically sorted: os < sys
testpackage2/latesymbolimport.py:2: symbol import follows non-symbol import: mercurial.node
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