Abort pip cache commands when cache is disabled

news/8124.bugfix

@@ -0,0 +1 @@
+Abort pip cache commands early when cache is disabled.

src/pip/_internal/commands/cache.py

@@ -48,6 +48,11 @@ def run(self, options, args):
             "purge": self.purge_cache,
         }
 
+        if not options.cache_dir:
+            logger.error("pip cache commands can not "
+                         "function since cache is disabled.")
+            return ERROR
+
         # Determine action
         if not args or args[0] not in handlers:
             logger.error("Need an action ({}) to perform.".format(

tests/functional/test_cache.py

@@ -216,3 +216,15 @@ def test_cache_purge_too_many_args(script, wheel_cache_files):
     # Make sure nothing was deleted.
     for filename in wheel_cache_files:
         assert os.path.exists(filename)
+
+
+@pytest.mark.parametrize("command", ["info", "list", "remove", "purge"])
+def test_cache_abort_when_no_cache_dir(script, command):
+    """Running any pip cache command when cache is disabled should
+    abort and log an informative error"""
+    result = script.pip('cache', command, '--no-cache-dir',
+                        expect_error=True)
+    assert result.stdout == ''
+
+    assert ('ERROR: pip cache commands can not function'
+            ' since cache is disabled.' in result.stderr.splitlines())