Print usage for module tool without subcommand (#1515)

* Print usage for module tool without subcommand

src/inmanta/app.py

@@ -53,7 +53,7 @@
 
 from inmanta import const, module, moduletool, protocol
 from inmanta.ast import CompilerException
-from inmanta.command import CLIException, Commander, command
+from inmanta.command import CLIException, Commander, command, ShowUsageException
 from inmanta.compiler import do_compile
 from inmanta.config import Config
 from inmanta.const import EXIT_START_FAILED
@@ -625,6 +625,9 @@ def report(e: Exception) -> None:
 
     try:
         options.func(options)
+    except ShowUsageException as e:
+        print(e.args[0], file=sys.stderr)
+        parser.print_usage()
     except CLIException as e:
         report(e)
         sys.exit(e.exitcode)

src/inmanta/command.py

@@ -18,11 +18,17 @@
 
 
 class CLIException(Exception):
-    def __init__(self, exitcode, *args, **kwargs):
+    def __init__(self, exitcode: int, *args, **kwargs):
         self.exitcode = exitcode
         super(CLIException, self).__init__(*args, **kwargs)
 
 
+class ShowUsageException(Exception):
+    """
+        Raise this exception to show the usage message of the given level
+    """
+
+
 class Commander(object):
     """
         This class handles commands

src/inmanta/moduletool.py

@@ -33,7 +33,7 @@
 
 import inmanta
 from inmanta.ast import Namespace, RuntimeException
-from inmanta.command import CLIException
+from inmanta.command import CLIException, ShowUsageException
 from inmanta.const import MAX_UPDATE_ATTEMPT
 from inmanta.module import INSTALL_MASTER, INSTALL_RELEASES, Module, Project, gitprovider
 from inmanta.parser.plyInmantaParser import parse
@@ -80,7 +80,11 @@ def execute(self, cmd, args):
             outargs = {k: getattr(args, k) for k in margs if hasattr(args, k)}
             method(**outargs)
         else:
-            raise Exception("%s not implemented" % cmd)
+            if cmd is None or cmd == "":
+                msg = "A subcommand is required."
+            else:
+                msg = f"{cmd} does not exist."
+            raise ShowUsageException(msg)
 
     def get_project(self, load=False) -> Project:
         project = Project.get()

tests/test_app_cli.py

@@ -25,6 +25,7 @@
 import pytest
 
 from inmanta.app import cmd_parser
+from inmanta.command import ShowUsageException
 from inmanta.config import Config
 from inmanta.const import VersionState
 
@@ -85,6 +86,13 @@ def test_help_sub(inmanta_config, capsys):
     assert "update" in out
 
 
+def test_module_help(inmanta_config, capsys):
+    with pytest.raises(ShowUsageException) as info:
+        app(["module"])
+
+    assert info.value.args[0].startswith("A subcommand is required.")
+
+
 @pytest.mark.parametrize("push_method", [([]), (["-d"]), (["-d", "--full"])])
 @pytest.mark.asyncio
 async def test_export(tmpdir, server, client, push_method):