fix: require username and password to be specified

We didn't require username and password to be specified when one was
provided but not the other. Such as username being provided but without
a password, or vice versa. Due to that convert2rhel fails much later
in the process than other warnings.

This addresses that with warning messages and aligns with other cases
like activation_key and org

convert2rhel/toolopts.py

@@ -498,6 +498,18 @@ def _process_cli_options(self):
                 "Either the --org or the --activationkey option is missing. You can't use one without the other."
             )
 
+        if (parsed_opts.password or config_opts.password) and not (parsed_opts.username or config_opts.username):
+            loggerinst.warning(
+                "You have passed the RHSM password without an associated username. Please provide a username together"
+                " with the password."
+            )
+
+        if (parsed_opts.username or config_opts.username) and not (parsed_opts.password or config_opts.password):
+            loggerinst.warning(
+                "You have passed the RHSM username without an associated password. Please provide a password together"
+                " with the username."
+            )
+
 
 def _log_command_used():
     """We want to log the command used for convert2rhel to make it easier to know what command was used

convert2rhel/unit_tests/toolopts_test.py

@@ -668,3 +668,29 @@ def test_setting_no_rpm_va(argv, env_var, expected, message, monkeypatch, global
     assert global_tool_opts.no_rpm_va == expected
     if message:
         assert caplog.records[-1].message == message
+
+
+@pytest.mark.parametrize(
+    ("argv", "message"),
+    (
+        # The message is a log of used command
+        (mock_cli_arguments(["-u", "user", "-p", "pass"]), "-u ***** -p *****"),
+        (
+            mock_cli_arguments(["-p", "pass"]),
+            "You have passed the RHSM password without an associated username. Please provide a username together with the password",
+        ),
+        (
+            mock_cli_arguments(["-u", "user"]),
+            "You have passed the RHSM username without an associated password. Please provide a password together with the username",
+        ),
+    ),
+)
+def test_cli_userpass_specified(argv, message, monkeypatch, caplog, global_tool_opts):
+    monkeypatch.setattr(sys, "argv", argv)
+
+    try:
+        convert2rhel.toolopts.CLI()
+    except SystemExit:
+        # Don't care about the exception, focus on output message
+        pass
+    assert message in caplog.text