gh-143984: Replace optparse with argparse in Lib/test/test_decimal.py

[tonghuaroot]

Description

Lib/test/test_decimal.py currently uses the deprecated optparse module for parsing command-line arguments. This task involves migrating it to use argparse.

Proposed Changes

• Replace optparse imports with argparse.
• Update argument parsing logic to use argparse.ArgumentParser.
• Ensure all existing command-line options (--debug, --skip) are supported.
• Fix any formatting issues (e.g. % in help strings).

Verification

• Run python Lib/test/test_decimal.py --help
• Run python Lib/test/test_decimal.py --skip

• Issue: Modernize Lib/test/test_decimal.py: use argparse instead of optparse #143984

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[bedevere-app]

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If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[bedevere-app]

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If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[hugovk]

As mentioned in the issue, optparse is no longer deprecated.

Suggested change

	Replace the usage of the deprecated optparse module with argparse in Lib/test/test_decimal.py.
	Replace :mod:`optparse` with :mod:`argparse` in ``Lib/test/test_decimal.py``.

[hugovk]

(This replaces my previous review.)

Let argparse generate the usage, and it'll use colour for the different parts.

And put the positional arg first, to match help output.

The short option usually goes before the long, and this matches -h, --help. Also wrap long lines.

Finally, the previous usage made it clear you couldn't skip AND pass a list of tests: [{--skip | test1 [test2 [...]]}]

Although optparse didn't enforce it.

With argparse, we can enforce it with a mutually exclusive group:

Suggested change

	import argparse
	parser = argparse.ArgumentParser(usage="test_decimal.py [--debug] [{--skip | test1 [test2 [...]]}]")
	parser.add_argument('--debug', '-d', action='store_true', help='shows the test number and context before each test')
	parser.add_argument('--skip', '-s', action='store_true', help='skip over 90%% of the arithmetic tests')
	parser.add_argument('tests', nargs='*', help='specific tests to run')
	import argparse
	parser = argparse.ArgumentParser()
	group = parser.add_mutually_exclusive_group()
	group.add_argument("tests", nargs="*", default=[], help="specific tests to run")
	group.add_argument(
	"-s",
	"--skip",
	action="store_true",
	help="skip over 90%% of the arithmetic tests",
	)
	parser.add_argument(
	"-d",
	"--debug",
	action="store_true",
	help="shows the test number and context before each test",
	)