From 2103cf2f9d5f60117ed5b47c7a166ee544015717 Mon Sep 17 00:00:00 2001
From: Bruno Alla <alla.brunoo@gmail.com>
Date: Wed, 5 Jun 2019 19:00:43 +0100
Subject: [PATCH] Add a pre-generation hook to avoid non-lowercase slugs -
 fixes #2042

---
 hooks/pre_gen_project.py              |  4 ++++
 tests/test_cookiecutter_generation.py | 12 ++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/hooks/pre_gen_project.py b/hooks/pre_gen_project.py
index e7bc1e39..91332f14 100644
--- a/hooks/pre_gen_project.py
+++ b/hooks/pre_gen_project.py
@@ -22,6 +22,10 @@ if hasattr(project_slug, "isidentifier"):
         project_slug.isidentifier()
     ), "'{}' project slug is not a valid Python identifier.".format(project_slug)
 
+assert (
+    project_slug == project_slug.lower()
+), "'{}' project slug should be all lowercase".format(project_slug)
+
 assert (
     "\\" not in "{{ cookiecutter.author_name }}"
 ), "Don't include backslashes in author name."
diff --git a/tests/test_cookiecutter_generation.py b/tests/test_cookiecutter_generation.py
index 4292f989..77f71df5 100755
--- a/tests/test_cookiecutter_generation.py
+++ b/tests/test_cookiecutter_generation.py
@@ -2,6 +2,7 @@ import os
 import re
 
 import pytest
+from cookiecutter.exceptions import FailedHookException
 from pytest_cases import pytest_fixture_plus
 import sh
 import yaml
@@ -145,3 +146,14 @@ def test_travis_invokes_pytest(cookies, context):
             assert yaml.load(travis_yml)["script"] == ["pytest"]
         except yaml.YAMLError as e:
             pytest.fail(e)
+
+
+@pytest.mark.parametrize("slug", ["project slug", "Project_Slug"])
+def test_invalid_slug(cookies, context, slug):
+    """Invalid slug should failed pre-generation hook."""
+    context.update({"project_slug": slug})
+
+    result = cookies.bake(extra_context=context)
+
+    assert result.exit_code != 0
+    assert isinstance(result.exception, FailedHookException)