Take additional CLI arguments from CSET_ADDOPTS env var

Fix test of CLI help

src/CSET/__init__.py

@@ -16,6 +16,7 @@
 
 import argparse
 import logging
+import os
 import sys
 from importlib.metadata import version
 from pathlib import Path
@@ -114,7 +115,8 @@ def main():
     )
     parser_cookbook.set_defaults(func=_cookbook_command)
 
-    args, unparsed_args = parser.parse_known_args()
+    cli_args = sys.argv[1:] + os.getenv("CSET_ADDOPTS", "").split()
+    args, unparsed_args = parser.parse_known_args(cli_args)
 
     # Setup logging.
     logging.captureWarnings(True)
@@ -139,7 +141,8 @@ def main():
             parser.print_usage()
             sys.exit(2)
     else:
-        parser.print_help()
+        parser.print_usage()
+        sys.exit(2)
 
 
 def _bake_command(args, unparsed_args):

tests/test_cli.py

@@ -29,14 +29,15 @@
 def test_command_line_help():
     """Check that help commands work."""
     subprocess.run(["cset", "--help"], check=True)
-    # Test verbose options. This is really just to up the coverage number.
-    subprocess.run(["cset", "-v"], check=True)
-    subprocess.run(["cset", "-vv"], check=True)
     subprocess.run(["cset", "--version"], check=True)
 
     # Gain coverage of __main__.py
     subprocess.run(["python3", "-m", "CSET", "-h"], check=True)
 
+    # Test verbose options. This is really just to up the coverage number.
+    subprocess.run(["cset", "-v"])
+    subprocess.run(["cset", "-vv"])
+
 
 def test_recipe_execution():
     """Test running CSET recipe from the command line."""