Merge pull request #2794 from thisch/catchlog

Merge pytest-catchlog plugin

AUTHORS

@@ -168,6 +168,7 @@ Tarcisio Fischer
 Tareq Alayan
 Ted Xiao
 Thomas Grainger
+Thomas Hisch
 Tom Viner
 Trevor Bekolay
 Tyler Goodlet

_pytest/config.py

@@ -105,7 +105,7 @@ def directory_arg(path, optname):
     "mark main terminal runner python fixtures debugging unittest capture skipping "
     "tmpdir monkeypatch recwarn pastebin helpconfig nose assertion "
     "junitxml resultlog doctest cacheprovider freeze_support "
-    "setuponly setupplan warnings").split()
+    "setuponly setupplan warnings logging").split()
 
 
 builtin_plugins = set(default_plugins)

_pytest/logging.py

@@ -0,0 +1,337 @@
+from __future__ import absolute_import, division, print_function
+
+import logging
+from contextlib import closing, contextmanager
+import sys
+import six
+
+import pytest
+import py
+
+
+DEFAULT_LOG_FORMAT = '%(filename)-25s %(lineno)4d %(levelname)-8s %(message)s'
+DEFAULT_LOG_DATE_FORMAT = '%H:%M:%S'
+
+
+def get_option_ini(config, *names):
+    for name in names:
+        ret = config.getoption(name)  # 'default' arg won't work as expected
+        if ret is None:
+            ret = config.getini(name)
+        if ret:
+            return ret
+
+
+def pytest_addoption(parser):
+    """Add options to control log capturing."""
+    group = parser.getgroup('logging')
+
+    def add_option_ini(option, dest, default=None, type=None, **kwargs):
+        parser.addini(dest, default=default, type=type,
+                      help='default value for ' + option)
+        group.addoption(option, dest=dest, **kwargs)
+
+    add_option_ini(
+        '--no-print-logs',
+        dest='log_print', action='store_const', const=False, default=True,
+        type='bool',
+        help='disable printing caught logs on failed tests.')
+    add_option_ini(
+        '--log-level',
+        dest='log_level', default=None,
+        help='logging level used by the logging module')
+    add_option_ini(
+        '--log-format',
+        dest='log_format', default=DEFAULT_LOG_FORMAT,
+        help='log format as used by the logging module.')
+    add_option_ini(
+        '--log-date-format',
+        dest='log_date_format', default=DEFAULT_LOG_DATE_FORMAT,
+        help='log date format as used by the logging module.')
+    add_option_ini(
+        '--log-cli-level',
+        dest='log_cli_level', default=None,
+        help='cli logging level.')
+    add_option_ini(
+        '--log-cli-format',
+        dest='log_cli_format', default=None,
+        help='log format as used by the logging module.')
+    add_option_ini(
+        '--log-cli-date-format',
+        dest='log_cli_date_format', default=None,
+        help='log date format as used by the logging module.')
+    add_option_ini(
+        '--log-file',
+        dest='log_file', default=None,
+        help='path to a file when logging will be written to.')
+    add_option_ini(
+        '--log-file-level',
+        dest='log_file_level', default=None,
+        help='log file logging level.')
+    add_option_ini(
+        '--log-file-format',
+        dest='log_file_format', default=DEFAULT_LOG_FORMAT,
+        help='log format as used by the logging module.')
+    add_option_ini(
+        '--log-file-date-format',
+        dest='log_file_date_format', default=DEFAULT_LOG_DATE_FORMAT,
+        help='log date format as used by the logging module.')
+
+
+@contextmanager
+def logging_using_handler(handler, logger=None):
+    """Context manager that safely registers a given handler."""
+    logger = logger or logging.getLogger(logger)
+
+    if handler in logger.handlers:  # reentrancy
+        # Adding the same handler twice would confuse logging system.
+        # Just don't do that.
+        yield
+    else:
+        logger.addHandler(handler)
+        try:
+            yield
+        finally:
+            logger.removeHandler(handler)
+
+
+@contextmanager
+def catching_logs(handler, formatter=None,
+                  level=logging.NOTSET, logger=None):
+    """Context manager that prepares the whole logging machinery properly."""
+    logger = logger or logging.getLogger(logger)
+
+    if formatter is not None:
+        handler.setFormatter(formatter)
+    handler.setLevel(level)
+
+    with logging_using_handler(handler, logger):
+        orig_level = logger.level
+        logger.setLevel(min(orig_level, level))
+        try:
+            yield handler
+        finally:
+            logger.setLevel(orig_level)
+
+
+class LogCaptureHandler(logging.StreamHandler):
+    """A logging handler that stores log records and the log text."""
+
+    def __init__(self):
+        """Creates a new log handler."""
+        logging.StreamHandler.__init__(self, py.io.TextIO())
+        self.records = []
+
+    def emit(self, record):
+        """Keep the log records in a list in addition to the log text."""
+        self.records.append(record)
+        logging.StreamHandler.emit(self, record)
+
+
+class LogCaptureFixture(object):
+    """Provides access and control of log capturing."""
+
+    def __init__(self, item):
+        """Creates a new funcarg."""
+        self._item = item
+
+    @property
+    def handler(self):
+        return self._item.catch_log_handler
+
+    @property
+    def text(self):
+        """Returns the log text."""
+        return self.handler.stream.getvalue()
+
+    @property
+    def records(self):
+        """Returns the list of log records."""
+        return self.handler.records
+
+    @property
+    def record_tuples(self):
+        """Returns a list of a striped down version of log records intended
+        for use in assertion comparison.
+
+        The format of the tuple is:
+
+            (logger_name, log_level, message)
+        """
+        return [(r.name, r.levelno, r.getMessage()) for r in self.records]
+
+    def clear(self):
+        """Reset the list of log records."""
+        self.handler.records = []
+
+    def set_level(self, level, logger=None):
+        """Sets the level for capturing of logs.
+
+        By default, the level is set on the handler used to capture
+        logs. Specify a logger name to instead set the level of any
+        logger.
+        """
+        if logger is None:
+            logger = self.handler
+        else:
+            logger = logging.getLogger(logger)
+        logger.setLevel(level)
+
+    @contextmanager
+    def at_level(self, level, logger=None):
+        """Context manager that sets the level for capturing of logs.
+
+        By default, the level is set on the handler used to capture
+        logs. Specify a logger name to instead set the level of any
+        logger.
+        """
+        if logger is None:
+            logger = self.handler
+        else:
+            logger = logging.getLogger(logger)
+
+        orig_level = logger.level
+        logger.setLevel(level)
+        try:
+            yield
+        finally:
+            logger.setLevel(orig_level)
+
+
+@pytest.fixture
+def caplog(request):
+    """Access and control log capturing.
+
+    Captured logs are available through the following methods::
+
+    * caplog.text()          -> string containing formatted log output
+    * caplog.records()       -> list of logging.LogRecord instances
+    * caplog.record_tuples() -> list of (logger_name, level, message) tuples
+    """
+    return LogCaptureFixture(request.node)
+
+
+def get_actual_log_level(config, *setting_names):
+    """Return the actual logging level."""
+
+    for setting_name in setting_names:
+        log_level = config.getoption(setting_name)
+        if log_level is None:
+            log_level = config.getini(setting_name)
+        if log_level:
+            break
+    else:
+        return
+
+    if isinstance(log_level, six.string_types):
+        log_level = log_level.upper()
+    try:
+        return int(getattr(logging, log_level, log_level))
+    except ValueError:
+        # Python logging does not recognise this as a logging level
+        raise pytest.UsageError(
+            "'{0}' is not recognized as a logging level name for "
+            "'{1}'. Please consider passing the "
+            "logging level num instead.".format(
+                log_level,
+                setting_name))
+
+
+def pytest_configure(config):
+    config.pluginmanager.register(LoggingPlugin(config),
+                                  'logging-plugin')
+
+
+class LoggingPlugin(object):
+    """Attaches to the logging module and captures log messages for each test.
+    """
+
+    def __init__(self, config):
+        """Creates a new plugin to capture log messages.
+
+        The formatter can be safely shared across all handlers so
+        create a single one for the entire test session here.
+        """
+        self.log_cli_level = get_actual_log_level(
+            config, 'log_cli_level', 'log_level') or logging.WARNING
+
+        self.print_logs = get_option_ini(config, 'log_print')
+        self.formatter = logging.Formatter(
+            get_option_ini(config, 'log_format'),
+            get_option_ini(config, 'log_date_format'))
+
+        log_cli_handler = logging.StreamHandler(sys.stderr)
+        log_cli_format = get_option_ini(
+            config, 'log_cli_format', 'log_format')
+        log_cli_date_format = get_option_ini(
+            config, 'log_cli_date_format', 'log_date_format')
+        log_cli_formatter = logging.Formatter(
+            log_cli_format,
+            datefmt=log_cli_date_format)
+        self.log_cli_handler = log_cli_handler  # needed for a single unittest
+        self.live_logs = catching_logs(log_cli_handler,
+                                       formatter=log_cli_formatter,
+                                       level=self.log_cli_level)
+
+        log_file = get_option_ini(config, 'log_file')
+        if log_file:
+            self.log_file_level = get_actual_log_level(
+                config, 'log_file_level') or logging.WARNING
+
+            log_file_format = get_option_ini(
+                config, 'log_file_format', 'log_format')
+            log_file_date_format = get_option_ini(
+                config, 'log_file_date_format', 'log_date_format')
+            self.log_file_handler = logging.FileHandler(
+                log_file,
+                # Each pytest runtests session will write to a clean logfile
+                mode='w')
+            log_file_formatter = logging.Formatter(
+                log_file_format,
+                datefmt=log_file_date_format)
+            self.log_file_handler.setFormatter(log_file_formatter)
+        else:
+            self.log_file_handler = None
+
+    @contextmanager
+    def _runtest_for(self, item, when):
+        """Implements the internals of pytest_runtest_xxx() hook."""
+        with catching_logs(LogCaptureHandler(),
+                           formatter=self.formatter) as log_handler:
+            item.catch_log_handler = log_handler
+            try:
+                yield  # run test
+            finally:
+                del item.catch_log_handler
+
+            if self.print_logs:
+                # Add a captured log section to the report.
+                log = log_handler.stream.getvalue().strip()
+                item.add_report_section(when, 'log', log)
+
+    @pytest.hookimpl(hookwrapper=True)
+    def pytest_runtest_setup(self, item):
+        with self._runtest_for(item, 'setup'):
+            yield
+
+    @pytest.hookimpl(hookwrapper=True)
+    def pytest_runtest_call(self, item):
+        with self._runtest_for(item, 'call'):
+            yield
+
+    @pytest.hookimpl(hookwrapper=True)
+    def pytest_runtest_teardown(self, item):
+        with self._runtest_for(item, 'teardown'):
+            yield
+
+    @pytest.hookimpl(hookwrapper=True)
+    def pytest_runtestloop(self, session):
+        """Runs all collected test items."""
+        with self.live_logs:
+            if self.log_file_handler is not None:
+                with closing(self.log_file_handler):
+                    with catching_logs(self.log_file_handler,
+                                       level=self.log_file_level):
+                        yield  # run all the tests
+            else:
+                yield  # run all the tests

changelog/2794.feature

@@ -0,0 +1,3 @@
+Pytest now captures and displays output from the standard `logging` module. The user can control the logging level to be captured by specifying options in ``pytest.ini``, the command line and also during individual tests using markers. Also, a ``caplog`` fixture is available that enables users to test the captured log during specific tests (similar to ``capsys`` for example). For more information, please see the `docs <https://docs.pytest.org/en/latest/logging.html>`_.
+
+This feature was introduced by merging the popular `pytest-catchlog <https://pypi.org/project/pytest-catchlog/>`_ plugin, thanks to `Thomas Hisch <https://github.com/thisch>`_. Be advised that during the merging the backward compatibility interface with the defunct ``pytest-capturelog`` has been dropped.

doc/en/contents.rst

@@ -30,6 +30,7 @@ Full pytest documentation
    xunit_setup
    plugins
    writing_plugins
+   logging
 
    goodpractices
    pythonpath