test that at least one cli group is expected in custom commands file

bocadillo/cli.py

@@ -53,7 +53,7 @@ def _load_group(self, path: str):
         groups = (val for val in ns.values() if isinstance(val, click.Group))
         group = next(groups, None)
         if group is None:
-            raise click.ClickException(
+            raise ValueError(
                 f"Expected at least one group in {path}, none found."
             )
         for name, cmd in group.commands.items():

tests/test_cli_custom_commands.py

@@ -1,7 +1,10 @@
 import os
 from inspect import cleandoc
 
+import pytest
+
 from bocadillo.cli import create_cli
+from tests.utils import env
 
 
 def test_can_init_custom_commands(runner, tmpdir):
@@ -34,10 +37,19 @@ def hello():
         )
     )
 
-    os.environ["BOCA_CUSTOM_COMMANDS_FILE"] = str(boca_dot_py)
+    with env("BOCA_CUSTOM_COMMANDS_FILE", str(boca_dot_py)):
+        cli = create_cli()
 
-    cli = create_cli()
     result = runner.invoke(cli, ["hello"])
 
     assert result.exit_code == 0
     assert result.output == "Hello!\n"
+
+
+def test_at_least_one_group_is_expected(runner, tmpdir):
+    boca_dot_py = tmpdir.join("boca.py")
+    boca_dot_py.write("import click")
+
+    with env("BOCA_CUSTOM_COMMANDS_FILE", str(boca_dot_py)):
+        with pytest.raises(ValueError):
+            create_cli()