Refactor log arguments and configuration.

To make using e3.log possible without e3.main, I've pulled the
command-line arguments for the logging group out of e3.main and put them
in e3.log. I've also created a new activate method that is driven by the
parsed arguments.

To make e3.log a bit more general, I allow the default logging level to
be specified. The default level is taken to be WARNING; in e3.main, this
is overridden to INFO, to match prior behavior.

I also downcased the titles of the argument groups, as this seems more
consistent with the output of argparse.

Finally, I cleaned up the language on one of the help options for the
log.

src/e3/log.py

@@ -4,6 +4,7 @@
 from dataclasses import dataclass
 
 import logging
+import os
 import re
 import sys
 import time
@@ -30,6 +31,7 @@
         Mapping,
     )
     from logging import _ExcInfoType
+    from argparse import ArgumentParser, _ArgumentGroup, Namespace
 
     T = TypeVar("T")
 
@@ -308,6 +310,95 @@ def add_log_handlers(
     logging.getLogger("").addHandler(handler)
 
 
+def add_logging_argument_group(
+    argument_parser: ArgumentParser, default_level: int = logging.WARNING,
+) -> _ArgumentGroup:
+    """Add an argument group with logging options to the argument parser.
+
+    To be used with `e3.log.activate_with_args`.
+
+    :param argument_parser: the parser in which the group will be created
+    :param default_level: the logging level that will be used by default
+    """
+    log_group = argument_parser.add_argument_group(title="logging arguments")
+    log_group.add_argument(
+        "-v",
+        "--verbose",
+        action="count",
+        default=0,
+        help="make the log output to the console more verbose",
+    )
+    log_group.add_argument(
+        "--log-file",
+        metavar="FILE",
+        default=None,
+        help="store all the logs into the specified file",
+    )
+    log_group.add_argument(
+        "--loglevel",
+        default=default_level,
+        help="set the console log level",
+        choices={
+            "DEBUG": logging.DEBUG,
+            "INFO": logging.INFO,
+            "WARNING": logging.WARNING,
+            "ERROR": logging.ERROR,
+            "CRITICAL": logging.CRITICAL,
+        },
+    )
+    log_group.add_argument(
+        "--nocolor",
+        default=False,
+        action="store_true",
+        help="disable color and progress bars",
+    )
+    log_group.add_argument(
+        "--json-logs",
+        default="json-logs" in os.environ.get("E3_ENABLE_FEATURE", "").split(","),
+        action="store_true",
+        help="enable JSON formatted logs. They can be activated as well by"
+        " setting the env var E3_ENABLE_FEATURE=json-logs.",
+    )
+    log_group.add_argument(
+        "--console-logs",
+        metavar="LINE_PREFIX",
+        help="disable color, progress bars, and redirect as much as"
+        " possible to stdout, starting lines with the given prefix.",
+    )
+
+    return log_group
+
+
+def activate_with_args(args: Namespace, default_level: int = logging.WARNING) -> None:
+    """Activate the e3 log using argument parsed.
+
+    To be used with `e3.log.add_logging_argument_group`.
+
+    :param args: the result of parsing arguments
+    :param default_level: the logging level assumed by default
+    """
+    global console_logs
+    global pretty_cli
+
+    if args.verbose > 0:
+        level = default_level - 10 * args.verbose
+    else:
+        level = args.loglevel
+
+    if args.console_logs:
+        console_logs = args.console_logs
+
+    if args.nocolor:
+        pretty_cli = False
+
+    activate(
+        level=level,
+        filename=args.log_file,
+        json_format=args.json_logs,
+        e3_debug=level == logging.DEBUG,
+    )
+
+
 def activate(
     stream_format: str = log_config.stream_fmt,
     file_format: str = log_config.file_fmt,

src/e3/main.py

@@ -81,54 +81,10 @@ def __init__(
         if argument_parser is None:
             argument_parser = ArgumentParser()
 
-        log_group = argument_parser.add_argument_group(title="Logging arguments")
-        log_group.add_argument(
-            "-v",
-            "--verbose",
-            action="count",
-            default=0,
-            help="make the log outputted on the console more verbose (this "
-            "sets the log level to DEBUG)",
-        )
-        log_group.add_argument(
-            "--log-file",
-            metavar="FILE",
-            default=None,
-            help="store all the logs into the specified file",
-        )
-        log_group.add_argument(
-            "--loglevel",
-            default=logging.INFO,
-            help="set the console log level",
-            choices={
-                "DEBUG": logging.DEBUG,
-                "INFO": logging.INFO,
-                "ERROR": logging.ERROR,
-                "CRITICAL": logging.CRITICAL,
-            },
-        )
-        log_group.add_argument(
-            "--nocolor",
-            default=False,
-            action="store_true",
-            help="disable color and progress bars",
-        )
-        log_group.add_argument(
-            "--json-logs",
-            default="json-logs" in os.environ.get("E3_ENABLE_FEATURE", "").split(","),
-            action="store_true",
-            help="enable JSON formatted logs. They can be activated as well by"
-            " setting the env var E3_ENABLE_FEATURE=json-logs.",
-        )
-        log_group.add_argument(
-            "--console-logs",
-            metavar="LINE_PREFIX",
-            help="disable color, progress bars, and redirect as much as"
-            " possible to stdout, starting lines with the given prefix.",
-        )
+        e3.log.add_logging_argument_group(argument_parser, default_level=logging.INFO)
 
         if platform_args:
-            plat_group = argument_parser.add_argument_group(title="Platform arguments")
+            plat_group = argument_parser.add_argument_group(title="platform arguments")
             plat_group.add_argument(
                 "--build",
                 default=None,  # to force autodetection
@@ -193,25 +149,8 @@ def parse_args(
         else:
             self.args = self.argument_parser.parse_args(args)
 
-        if self.args.nocolor:
-            e3.log.pretty_cli = False
-
         if not self.__log_handlers_set:
-            # First set level of verbosity
-            if self.args.verbose:
-                level = logging.DEBUG
-            else:
-                level = self.args.loglevel
-
-            if self.args.console_logs:
-                e3.log.console_logs = self.args.console_logs
-
-            e3.log.activate(
-                level=level,
-                filename=self.args.log_file,
-                json_format=self.args.json_logs,
-                e3_debug=self.args.verbose > 1,
-            )
+            e3.log.activate_with_args(self.args, logging.INFO)
             self.__log_handlers_set = True
 
         # Export options to env

tests/tests_e3/main/main_test.py

@@ -79,6 +79,7 @@ def test_mainprog_with_console_logs():
         r"^mymain:.*:.*: DEBUG    this is an info line\r?\n"
         "mymain:.*:.* DEBUG    this is a debug line",
         p.out,
+        re.MULTILINE,
     )