Respond to feedback, and add functional tests.

src/pip/_internal/cli/cmdoptions.py

@@ -31,7 +31,7 @@ from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 if MYPY_CHECK_RUNNING:
     from optparse import OptionParser, Values
-    from typing import Any, Callable, Dict, List, Optional, Tuple
+    from typing import Any, Callable, Dict, Optional, Tuple
 
     from pip._internal.cli.parser import ConfigOptionParser
 
@@ -498,8 +498,8 @@ platform = partial(
     action='append',
     default=None,
     help=("Only use wheels compatible with <platform>. Defaults to the "
-          "platform of the running system. Use multiple options to specify "
-          "multiple platforms supported by the target interpreter."),
+          "platform of the running system. Use this option multiple times to "
+          "specify multiple platforms supported by the target interpreter."),
 )  # type: Callable[..., Option]
 
 
@@ -592,8 +592,8 @@ abi = partial(
     default=None,
     help=("Only use wheels compatible with Python abi <abi>, e.g. 'pypy_41'. "
           "If not specified, then the current interpreter abi tag is used. "
-          "Use multiple options to specify multiple abis supported by the "
-          "target interpreter. Generally you will need to specify "
+          "Use this option multiple times to specify multiple abis supported "
+          "by the target interpreter. Generally you will need to specify "
           "--implementation, --platform, and --python-version when using this "
           "option."),
 )  # type: Callable[..., Option]

tests/functional/test_download.py

@@ -309,6 +309,21 @@ def test_download_specify_platform(script, data):
         Path('scratch') / 'fake-2.0-py2.py3-none-linux_x86_64.whl'
     )
 
+    # Test with multiple supported platforms specified.
+    data.reset()
+    fake_wheel(data, 'fake-3.0-py2.py3-none-linux_x86_64.whl')
+    result = script.pip(
+        'download', '--no-index', '--find-links', data.find_links,
+        '--only-binary=:all:',
+        '--dest', '.',
+        '--platform', 'manylinux1_x86_64', '--platform', 'linux_x86_64',
+        '--platform', 'any',
+        'fake==3'
+    )
+    result.did_create(
+        Path('scratch') / 'fake-3.0-py2.py3-none-linux_x86_64.whl'
+    )
+
 
 class TestDownloadPlatformManylinuxes(object):
     """
@@ -575,6 +590,22 @@ def test_download_specify_abi(script, data):
         expect_error=True,
     )
 
+    data.reset()
+    fake_wheel(data, 'fake-1.0-fk2-otherabi-fake_platform.whl')
+    result = script.pip(
+        'download', '--no-index', '--find-links', data.find_links,
+        '--only-binary=:all:',
+        '--dest', '.',
+        '--python-version', '2',
+        '--implementation', 'fk',
+        '--platform', 'fake_platform',
+        '--abi', 'fakeabi', '--abi', 'otherabi', '--abi', 'none',
+        'fake'
+    )
+    result.did_create(
+        Path('scratch') / 'fake-1.0-fk2-otherabi-fake_platform.whl'
+    )
+
 
 def test_download_specify_implementation(script, data):
     """