diff --git a/subcmds/init.py b/subcmds/init.py
index eb82e2e4..41578076 100644
--- a/subcmds/init.py
+++ b/subcmds/init.py
@@ -488,6 +488,9 @@ to update the working directory files.
     if opt.archive and opt.mirror:
       self.OptionParser.error('--mirror and --archive cannot be used together.')
 
+    if args:
+      self.OptionParser.error('init takes no arguments')
+
   def Execute(self, opt, args):
     git_require(MIN_GIT_VERSION_HARD, fail=True)
     if not git_require(MIN_GIT_VERSION_SOFT):
diff --git a/tests/test_subcmds.py b/tests/test_subcmds.py
new file mode 100644
index 00000000..2234e646
--- /dev/null
+++ b/tests/test_subcmds.py
@@ -0,0 +1,43 @@
+# Copyright (C) 2020 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Unittests for the subcmds module (mostly __init__.py than subcommands)."""
+
+import unittest
+
+import subcmds
+
+
+class AllCommands(unittest.TestCase):
+  """Check registered all_commands."""
+
+  def test_required_basic(self):
+    """Basic checking of registered commands."""
+    # NB: We don't test all subcommands as we want to avoid "change detection"
+    # tests, so we just look for the most common/important ones here that are
+    # unlikely to ever change.
+    for cmd in {'cherry-pick', 'help', 'init', 'start', 'sync', 'upload'}:
+      self.assertIn(cmd, subcmds.all_commands)
+
+  def test_naming(self):
+    """Verify we don't add things that we shouldn't."""
+    for cmd in subcmds.all_commands:
+      # Reject filename suffixes like "help.py".
+      self.assertNotIn('.', cmd)
+
+      # Make sure all '_' were converted to '-'.
+      self.assertNotIn('_', cmd)
+
+      # Reject internal python paths like "__init__".
+      self.assertFalse(cmd.startswith('__'))
diff --git a/tests/test_subcmds_init.py b/tests/test_subcmds_init.py
new file mode 100644
index 00000000..3a5ca3c2
--- /dev/null
+++ b/tests/test_subcmds_init.py
@@ -0,0 +1,49 @@
+# Copyright (C) 2020 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Unittests for the subcmds/init.py module."""
+
+import unittest
+
+from subcmds import init
+
+
+class InitCommand(unittest.TestCase):
+  """Check registered all_commands."""
+
+  def setUp(self):
+    self.cmd = init.Init()
+
+  def test_cli_parser_good(self):
+    """Check valid command line options."""
+    ARGV = (
+        [],
+    )
+    for argv in ARGV:
+      opts, args = self.cmd.OptionParser.parse_args(argv)
+      self.cmd.ValidateOptions(opts, args)
+
+  def test_cli_parser_bad(self):
+    """Check invalid command line options."""
+    ARGV = (
+        # Too many arguments.
+        ['asdf'],
+
+        # Conflicting options.
+        ['--mirror', '--archive'],
+    )
+    for argv in ARGV:
+      opts, args = self.cmd.OptionParser.parse_args(argv)
+      with self.assertRaises(SystemExit):
+        self.cmd.ValidateOptions(opts, args)