Add format_command_args() with tests.

src/pip/_internal/utils/misc.py

@@ -650,6 +650,21 @@ def unpack_file(
         )
 
 
+def format_command_args(args):
+    # type: (List[str]) -> str
+    """
+    Format command arguments for display.
+    """
+    parts = []
+    for arg in args:
+        if ' ' in arg or '\n' in arg or '"' in arg or "'" in arg:
+            arg = '"%s"' % arg.replace('"', '\\"')
+        parts.append(arg)
+    command = ' '.join(parts)
+
+    return command
+
+
 def call_subprocess(
     cmd,  # type: List[str]
     show_stdout=False,  # type: bool
@@ -699,12 +714,8 @@ def call_subprocess(
     else:
         stdout = subprocess.PIPE
     if command_desc is None:
-        cmd_parts = []
-        for part in cmd:
-            if ' ' in part or '\n' in part or '"' in part or "'" in part:
-                part = '"%s"' % part.replace('"', '\\"')
-            cmd_parts.append(part)
-        command_desc = ' '.join(cmd_parts)
+        command_desc = format_command_args(cmd)
+
     logger.debug("Running command %s", command_desc)
     env = os.environ.copy()
     if extra_environ:

src/pip/_internal/wheel.py

@@ -786,7 +786,7 @@ def should_use_ephemeral_cache(
     return True
 
 
-def format_command(
+def format_command_result(
     command_args,  # type: List[str]
     command_output,  # type: str
 ):
@@ -825,7 +825,7 @@ def get_legacy_build_wheel_path(
         msg = (
             'Legacy build of wheel for {!r} created no files.\n'
         ).format(req.name)
-        msg += format_command(command_args, command_output)
+        msg += format_command_result(command_args, command_output)
         logger.warning(msg)
         return None
 
@@ -834,7 +834,7 @@ def get_legacy_build_wheel_path(
             'Legacy build of wheel for {!r} created more than one file.\n'
             'Filenames (choosing first): {}\n'
         ).format(req.name, names)
-        msg += format_command(command_args, command_output)
+        msg += format_command_result(command_args, command_output)
         logger.warning(msg)
 
     return os.path.join(temp_dir, names[0])

tests/unit/test_utils.py

@@ -24,10 +24,11 @@ from pip._internal.utils.encoding import auto_decode
 from pip._internal.utils.glibc import check_glibc_version
 from pip._internal.utils.hashes import Hashes, MissingHashes
 from pip._internal.utils.misc import (
-    call_subprocess, egg_link_path, ensure_dir, get_installed_distributions,
-    get_prog, make_vcs_requirement_url, normalize_path, redact_netloc,
-    redact_password_from_url, remove_auth_from_url, rmtree,
-    split_auth_from_netloc, untar_file, unzip_file,
+    call_subprocess, egg_link_path, ensure_dir, format_command_args,
+    get_installed_distributions, get_prog, make_vcs_requirement_url,
+    normalize_path, redact_netloc, redact_password_from_url,
+    remove_auth_from_url, rmtree, split_auth_from_netloc, untar_file,
+    unzip_file,
 )
 from pip._internal.utils.packaging import check_dist_requires_python
 from pip._internal.utils.temp_dir import AdjacentTempDirectory, TempDirectory
@@ -724,6 +725,16 @@ class TestGetProg(object):
         assert get_prog() == expected
 
 
+@pytest.mark.parametrize('args, expected', [
+    (['pip', 'list'], 'pip list'),
+    (['foo', 'space space', 'new\nline', 'double"quote', "single'quote"],
+     'foo "space space" "new\nline" "double\\"quote" "single\'quote"'),
+])
+def test_format_command_args(args, expected):
+    actual = format_command_args(args)
+    assert actual == expected
+
+
 def test_call_subprocess_works__no_keyword_arguments():
     result = call_subprocess(
         [sys.executable, '-c', 'print("Hello")'],

tests/unit/test_wheel.py

@@ -99,9 +99,9 @@ def test_should_use_ephemeral_cache__issue_6197(
     assert ephem_cache is expected
 
 
-def test_format_command__INFO(caplog):
+def test_format_command_result__INFO(caplog):
     caplog.set_level(logging.INFO)
-    actual = wheel.format_command(
+    actual = wheel.format_command_result(
         command_args=['arg1', 'arg2'],
         command_output='output line 1\noutput line 2\n',
     )
@@ -117,9 +117,9 @@ def test_format_command__INFO(caplog):
     # Test no trailing newline.
     'output line 1\noutput line 2',
 ])
-def test_format_command__DEBUG(caplog, command_output):
+def test_format_command_result__DEBUG(caplog, command_output):
     caplog.set_level(logging.DEBUG)
-    actual = wheel.format_command(
+    actual = wheel.format_command_result(
         command_args=['arg1', 'arg2'],
         command_output=command_output,
     )
@@ -133,9 +133,9 @@ def test_format_command__DEBUG(caplog, command_output):
 
 
 @pytest.mark.parametrize('log_level', ['DEBUG', 'INFO'])
-def test_format_command__empty_output(caplog, log_level):
+def test_format_command_result__empty_output(caplog, log_level):
     caplog.set_level(log_level)
-    actual = wheel.format_command(
+    actual = wheel.format_command_result(
         command_args=['arg1', 'arg2'],
         command_output='',
     )