Add support for click 8.x (cookiecutter#1569)

* Make read_user_dict compatible with click 8.x

The `read_user_dict` function uses a "default" sentinel instead of the actual
default value. Being a JSON dict, the latter would often be hard to type.

Under click 8.x, the default value for `click.prompt` is passed to the
`read_proc` callback. We use this callback to load JSON from the user input, and
this would choke on an input like "default" (without quotes). Therefore, change
the callback to return the default value when it receives the "default"
sentinel.

Under click 7.x (which is our minimum version), the default value for
`click.prompt` is returned as-is. Therefore, continue to handle the case where
`click.prompt` returns "default" instead of the actual default value, but only
if we're actually running under click 7.x.

(Checking for click 7.x is only done for clarity. Under click 8.x,
`click.prompt` would never return "default", even if a user entered it as a
valid JSON string. This is because our callback requires a dict, not a string.)

* test: Expect read_user_dict to call click.prompt with partial object

Previously, tests for `read_user_dict` expected `process_json` to be passed to
click.prompt directly. Instead, we now pass an instance of `functools.partial`,
so adapt the mock to reflect that.

* test: Avoid mocking `click.prompt` when testing defaults

Do not mock `click.prompt` when testing that `read_user_dict` returns the proper
default value (rather than the sentinel "default"). Mocking `click.prompt`
prevents our callback from running, and under click >= 8.0 we process the
sentinel in the callback. Instead, use `click.testing.CliRunner` to fake
standard input.

* test: Adapt regression test for default handling

Expect `json.loads` not to be called with the sentinel ("default"). Previously,
the test expected `process_json` not to be called, but under click >= 8.0 that
is now where we handle the sentinel.

* Update dependencies for click 8.x

cookiecutter/prompt.py

@@ -1,4 +1,5 @@
 """Functions for prompting the user for project info."""
+import functools
 import json
 from collections import OrderedDict
 
@@ -78,11 +79,18 @@ def read_user_choice(var_name, options):
     return choice_map[user_choice]
 
 
-def process_json(user_value):
+DEFAULT_DISPLAY = 'default'
+
+
+def process_json(user_value, default_value=None):
     """Load user-supplied value as a JSON dict.
 
     :param str user_value: User-supplied value to load as a JSON dict
     """
+    if user_value == DEFAULT_DISPLAY:
+        # Return the given default w/o any processing
+        return default_value
+
     try:
         user_dict = json.loads(user_value, object_pairs_hook=OrderedDict)
     except Exception:
@@ -107,15 +115,16 @@ def read_user_dict(var_name, default_value):
     if not isinstance(default_value, dict):
         raise TypeError
 
-    default_display = 'default'
-
     user_value = click.prompt(
-        var_name, default=default_display, type=click.STRING, value_proc=process_json
+        var_name,
+        default=DEFAULT_DISPLAY,
+        type=click.STRING,
+        value_proc=functools.partial(process_json, default_value=default_value),
     )
 
-    if user_value == default_display:
-        # Return the given default w/o any processing
-        return default_value
+    if click.__version__.startswith("7.") and user_value == DEFAULT_DISPLAY:
+        # click 7.x does not invoke value_proc on the default value.
+        return default_value  # pragma: no cover
     return user_value
 
 

setup.cfg

@@ -62,7 +62,7 @@ setup_requires =
 install_requires =
     binaryornot>=0.4.4
     Jinja2>=2.7,<4.0.0
-    click>=7.0,<8.0.0
+    click>=7.0,<9.0.0
     pyyaml>=5.3.1
     jinja2-time>=0.2.0
     python-slugify>=4.0.0

tests/test_read_user_dict.py

@@ -92,35 +92,35 @@ def test_should_call_prompt_with_process_json(mocker):
 
     read_user_dict('name', {'project_slug': 'pytest-plugin'})
 
-    assert mock_prompt.call_args == mocker.call(
-        'name', type=click.STRING, default='default', value_proc=process_json,
-    )
+    args, kwargs = mock_prompt.call_args
+
+    assert args == ('name',)
+    assert kwargs['type'] == click.STRING
+    assert kwargs['default'] == 'default'
+    assert kwargs['value_proc'].func == process_json
 
 
-def test_should_not_call_process_json_default_value(mocker, monkeypatch):
-    """Make sure that `process_json` is not called when using default value."""
-    mock_process_json = mocker.patch('cookiecutter.prompt.process_json', autospec=True)
+def test_should_not_load_json_from_sentinel(mocker):
+    """Make sure that `json.loads` is not called when using default value."""
+    mock_json_loads = mocker.patch(
+        'cookiecutter.prompt.json.loads', autospec=True, return_value={}
+    )
 
     runner = click.testing.CliRunner()
     with runner.isolation(input="\n"):
         read_user_dict('name', {'project_slug': 'pytest-plugin'})
 
-    mock_process_json.assert_not_called()
+    mock_json_loads.assert_not_called()
 
 
-def test_read_user_dict_default_value(mocker):
+@pytest.mark.parametrize("input", ["\n", "default\n"])
+def test_read_user_dict_default_value(mocker, input):
     """Make sure that `read_user_dict` returns the default value.
 
     Verify return of a dict variable rather than the display value.
     """
-    mock_prompt = mocker.patch(
-        'cookiecutter.prompt.click.prompt', autospec=True, return_value='default',
-    )
-
-    val = read_user_dict('name', {'project_slug': 'pytest-plugin'})
-
-    assert mock_prompt.call_args == mocker.call(
-        'name', type=click.STRING, default='default', value_proc=process_json,
-    )
+    runner = click.testing.CliRunner()
+    with runner.isolation(input=input):
+        val = read_user_dict('name', {'project_slug': 'pytest-plugin'})
 
     assert val == {'project_slug': 'pytest-plugin'}