Added uuid extension to be able to generate uuids (cookiecutter#1493)

* Update extensions.py

* Added tests and full function

* fixed bug

* fixed call

* Fixed doc string

* linting

cookiecutter/environment.py

@@ -26,6 +26,7 @@ def __init__(self, **kwargs):
             'cookiecutter.extensions.JsonifyExtension',
             'cookiecutter.extensions.RandomStringExtension',
             'cookiecutter.extensions.SlugifyExtension',
+            'cookiecutter.extensions.UUIDExtension',
             'jinja2_time.TimeExtension',
         ]
         extensions = default_extensions + self._read_extensions(context)

cookiecutter/extensions.py

@@ -1,6 +1,7 @@
 """Jinja2 extensions."""
 import json
 import string
+import uuid
 from secrets import choice
 
 from jinja2.ext import Extension
@@ -49,3 +50,17 @@ def slugify(value, **kwargs):
             return pyslugify(value, **kwargs)
 
         environment.filters['slugify'] = slugify
+
+
+class UUIDExtension(Extension):
+    """Jinja2 Extension to generate uuid4 string."""
+
+    def __init__(self, environment):
+        """Jinja2 Extension constructor."""
+        super(UUIDExtension, self).__init__(environment)
+
+        def uuid4():
+            """Generate UUID4."""
+            return str(uuid.uuid4())
+
+        environment.globals.update(uuid4=uuid4)

docs/advanced/template_extensions.rst

@@ -32,6 +32,7 @@ By default Cookiecutter includes the following extensions:
 - ``cookiecutter.extensions.JsonifyExtension``
 - ``cookiecutter.extensions.RandomStringExtension``
 - ``cookiecutter.extensions.SlugifyExtension``
+- ``cookiecutter.extensions.UUIDExtension``
 - ``jinja2_time.TimeExtension``
 
 Jsonify extension
@@ -109,3 +110,23 @@ be passed to `slugify()`.
 .. _`now`: https://github.com/hackebrot/jinja2-time#now-tag
 .. _`jinja2_time.TimeExtension`: https://github.com/hackebrot/jinja2-time
 .. _`python-slugify`: https://github.com/un33k/python-slugify
+
+UUID4 extension
+~~~~~~~~~~~~~~~~~~~~~~~
+
+*New in Cookiecutter 1.x*
+
+The ``cookiecutter.extensions.UUIDExtension`` extension provides a ``uuid4()``
+method in templates that generates a uuid4.
+
+Generate a uuid4 string:
+
+.. code-block:: jinja
+
+    {{ uuid4() }}
+
+Outputs:
+
+.. code-block:: text
+
+    83b5de62-31b4-4a1e-83fa-8c548de65a11

tests/test-extensions/default/{{cookiecutter.project_slug}}/id

@@ -0,0 +1 @@
+{{ uuid4() }}

tests/test_default_extensions.py

@@ -3,6 +3,7 @@
 
 import freezegun
 import pytest
+import uuid
 
 from cookiecutter.main import cookiecutter
 
@@ -46,3 +47,18 @@ def test_jinja2_slugify_extension(tmpdir):
     )
 
     assert os.path.basename(project_dir) == "it-s-slugified-foobar"
+
+
+def test_jinja2_uuid_extension(tmpdir):
+    """Verify Jinja2 uuid extension work correctly."""
+    project_dir = cookiecutter(
+        'tests/test-extensions/default/', no_input=True, output_dir=str(tmpdir)
+    )
+    changelog_file = os.path.join(project_dir, 'id')
+    assert os.path.isfile(changelog_file)
+
+    with open(changelog_file, 'r', encoding='utf-8') as f:
+        changelog_lines = f.readlines()
+
+    uuid.UUID(changelog_lines[0], version=4)
+    assert True

tests/test_environment.py

@@ -22,3 +22,4 @@ def test_env_should_come_with_default_extensions():
     assert 'cookiecutter.extensions.JsonifyExtension' in env.extensions
     assert 'cookiecutter.extensions.RandomStringExtension' in env.extensions
     assert 'cookiecutter.extensions.SlugifyExtension' in env.extensions
+    assert 'cookiecutter.extensions.UUIDExtension' in env.extensions