Catches/silences stdout/stderr output.
Project description
A context manager that catches/suppresses output from sys.stderr and sys.stdout.
API
StdOutCatcher / StdErrCatcher
StdOutCatcher(escaped=False, max_length=0)
Arguments
escaped: If truthy, output is “encoded” using repr(), but without quotes. Default: False
max_length: If non-zero, final output will not exceed max_length. Once max_length is reached, further write() calls will not write to the original stream. Default: 0
Usage
from outputcatcher import StdErrCatcher, StdOutCatcher
# Catching stdout
with StdOutCatcher() as fakeout:
print('This is a test. you shouldn\'t see it right away.')
print('Captured stdout: {}'.format(fakeout.output))
# Catching stderr
with StdErrCatcher() as fakeerr:
print('Testing stderr output.', file=sys.stderr)
print('Captured stderr: {}'.format(fakeerr.output))
ProcessOutput
ProcessOutput(args, stdin_data=None, timeout=None, **popenkwargs)
After initializing a ProcessOutput object with a command to run, and optional stdin input data, it can either be used as a context manager or the run() method must be called. timeout is passed to self.proc.wait() before returning the output.
Arguments
args: Command arguments, same as subprocess.Popen.
stdin_data: str or bytes to send to command as stdin. Default: None
timeout: Time to wait for process after collecting data. Default: None
**popenkwargs: Any extra kwargs for Popen().
Usage
from outputcatcher import ProcessOutput
# Basic usage:
with ProcessOutput(['ls']) as p:
print(p.stdout.decode())
# Checking for stdout and stderr:
with ProcessOutput(['ls', '/totally_nonexistent_dir']) as p:
if p.stdout:
print('Wow, it really does exist: {}'.format(p.stdout.decode()))
else:
print(p.stderr.decode())
# Without a context manager:
p = ProcessOutput(['ls'])
stdout, stderr = p.run()
# Sending stdin data to a process:
stdin_data = 'Hello cat!'
with ProcessOutput(['cat'], stdin_data=stdin_data) as p:
assert p.stdout.decode() == stdin_data
# cat received the data, and piped it back.
print(p.stdout.decode())
Project details
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