gh-131178: Add tests for ftplib command-line interface - #161080

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Could you check the failures in the CI?

Hi @orsenthil,

The initial failure was caused by missing parentheses on @requires_subprocess in Lib/test/test_ftplib.py, which caused a TypeError at import time when the test runner loaded the module.

I pushed commit 2f1b646 to fix the decorator invocation to @requires_subprocess(), and also mocked netrc.netrc in the command tests to ensure hermetic execution regardless of the runner environment.

All test jobs across all platforms have now passed. Please let me know if any further changes are needed.

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Thanks @rudy-07 for the PR, and @orsenthil for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14, 3.15.
🐍🍒⛏🤖

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 CentOS9 NoGIL 3.x (tier-1) has failed when building commit c29f95a.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1609/builds/7679) and take a look at the build logs.
4. Check if the failure is related to this commit (c29f95a) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1609/builds/7679

Failed tests:

• test_ftplib

Failed subtests:

• test_cli_retrieve_file - test.test_ftplib.CommandLineTest.test_cli_retrieve_file

Summary of the results of the build (if available):

==

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/unittest/mock.py", line 1437, in patched
    return func(*newargs, **newkeywargs)
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/test/test_ftplib.py", line 1246, in test_cli_retrieve_file
    ftplib.test()
    ~~~~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.itamaro-centos-aws.nogil/build/Lib/ftplib.py", line 968, in test
    sys.stdout.buffer.write, 1024)
    ^^^^^^^^^^^^^^^^^
AttributeError: '_io.StringIO' object has no attribute 'buffer'

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot ARM64 macOS 3.x (tier-1) has failed when building commit c29f95a.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/725/builds/15020) and take a look at the build logs.
4. Check if the failure is related to this commit (c29f95a) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/725/builds/15020

Failed tests:

• test_ftplib

Failed subtests:

• test_cli_retrieve_file - test.test_ftplib.CommandLineTest.test_cli_retrieve_file

Summary of the results of the build (if available):

==

Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/unittest/mock.py", line 1437, in patched
    return func(*newargs, **newkeywargs)
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_ftplib.py", line 1246, in test_cli_retrieve_file
    ftplib.test()
    ~~~~~~~~~~~^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/ftplib.py", line 968, in test
    sys.stdout.buffer.write, 1024)
    ^^^^^^^^^^^^^^^^^
AttributeError: '_io.StringIO' object has no attribute 'buffer'

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot ARM Raspbian 3.x (tier-3) has failed when building commit c29f95a.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/424/builds/15603) and take a look at the build logs.
4. Check if the failure is related to this commit (c29f95a) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/424/builds/15603

Failed tests:

• test_ftplib

Failed subtests:

• test_cli_retrieve_file - test.test_ftplib.CommandLineTest.test_cli_retrieve_file

Summary of the results of the build (if available):

==

Traceback (most recent call last):
  File "/var/lib/buildbot/workers/3.x.gps-raspbian.nondebug/build/Lib/unittest/mock.py", line 1437, in patched
    return func(*newargs, **newkeywargs)
  File "/var/lib/buildbot/workers/3.x.gps-raspbian.nondebug/build/Lib/test/test_ftplib.py", line 1246, in test_cli_retrieve_file
    ftplib.test()
    ~~~~~~~~~~~^^
  File "/var/lib/buildbot/workers/3.x.gps-raspbian.nondebug/build/Lib/ftplib.py", line 968, in test
    sys.stdout.buffer.write, 1024)
    ^^^^^^^^^^^^^^^^^
AttributeError: '_io.StringIO' object has no attribute 'buffer'

Thanks for merging! I noticed the buildbot failure in test_cli_retrieve_file caused by sys.stdout lacking a .buffer attribute under regrtest. I will open a follow-up PR shortly to mock sys.stdout properly.

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot ARM64 Raspbian Debug 3.x (tier-3) has failed when building commit c29f95a.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1829/builds/3671) and take a look at the build logs.
4. Check if the failure is related to this commit (c29f95a) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1829/builds/3671

Failed tests:

• test_ftplib

Failed subtests:

• test_cli_retrieve_file - test.test_ftplib.CommandLineTest.test_cli_retrieve_file

Summary of the results of the build (if available):

==

Traceback (most recent call last):
  File "/mnt/ssd/buildbot/buildarea/3.x.savannah-raspbian/build/Lib/unittest/mock.py", line 1437, in patched
    return func(*newargs, **newkeywargs)
  File "/mnt/ssd/buildbot/buildarea/3.x.savannah-raspbian/build/Lib/test/test_ftplib.py", line 1246, in test_cli_retrieve_file
    ftplib.test()
    ~~~~~~~~~~~^^
  File "/mnt/ssd/buildbot/buildarea/3.x.savannah-raspbian/build/Lib/ftplib.py", line 968, in test
    sys.stdout.buffer.write, 1024)
    ^^^^^^^^^^^^^^^^^
AttributeError: '_io.StringIO' object has no attribute 'buffer'

I opened a follow-up PR to fix the sys.stdout.buffer AttributeError in est_cli_retrieve_file: #161135.