Automatically generate cassette names from function names. Add

`path_transformer` and `func_path_generator`. Closes #151.

README.md

@@ -389,6 +389,43 @@ my_vcr = config.VCR(custom_patches=((where_the_custom_https_connection_lives, 'C
 @my_vcr.use_cassette(...)
 ```
 
+## Automatic Cassette Naming
+
+VCR.py now allows the omission of the path argument to the
+use_cassette function. Both of the following are now legal/should work
+
+``` python
+@my_vcr.use_cassette
+def my_test_function():
+    ...
+```
+
+``` python
+@my_vcr.use_cassette()
+def my_test_function():
+    ...
+```
+
+In both cases, VCR.py will use a path that is generated from the
+provided test function's name. If no `cassette_library_dir` has been
+set, the cassette will be in a file with the name of the test function
+in directory of the file in which the test function is declared. If a
+`cassette_library_dir` is set, has been set, the cassette will appear
+in that directory in a file with the name of the decorated function.
+
+It is possible to control the path produced by the automatic naming
+machinery by customizing the `path_transformer` and
+`func_path_generator` vcr variables. To add an extension to all
+cassette names, use `VCR.ensure_suffix` as follows:
+
+``` python
+my_vcr = VCR(path_transformer=VCR.ensure_suffix('.yaml'))
+
+@my_vcr.use_cassette
+def my_test_function():
+
+```
+
 ## Installation
 
 VCR.py is a package on PyPI, so you can `pip install vcrpy` (first you may need

tests/unit/test_cassettes.py

@@ -1,4 +1,6 @@
 import copy
+import inspect
+import os
 
 from six.moves import http_client as httplib
 import contextlib2
@@ -12,14 +14,13 @@ from vcr.patch import force_reset
 from vcr.stubs import VCRHTTPSConnection
 
 
-
 def test_cassette_load(tmpdir):
     a_file = tmpdir.join('test_cassette.yml')
     a_file.write(yaml.dump({'interactions': [
         {'request': {'body': '', 'uri': 'foo', 'method': 'GET', 'headers': {}},
          'response': 'bar'}
     ]}))
-    a_cassette = Cassette.load(str(a_file))
+    a_cassette = Cassette.load(path=str(a_file))
     assert len(a_cassette) == 1
 
 
@@ -87,33 +88,35 @@ def make_get_request():
 @mock.patch('vcr.cassette.Cassette.can_play_response_for', return_value=True)
 @mock.patch('vcr.stubs.VCRHTTPResponse')
 def test_function_decorated_with_use_cassette_can_be_invoked_multiple_times(*args):
-    decorated_function = Cassette.use('test')(make_get_request)
-    for i in range(2):
+    decorated_function = Cassette.use(path='test')(make_get_request)
+    for i in range(4):
          decorated_function()
 
 
 def test_arg_getter_functionality():
-    arg_getter = mock.Mock(return_value=('test', {}))
+    arg_getter = mock.Mock(return_value={'path': 'test'})
     context_decorator = Cassette.use_arg_getter(arg_getter)
 
     with context_decorator as cassette:
         assert cassette._path == 'test'
 
-    arg_getter.return_value = ('other', {})
+    arg_getter.return_value = {'path': 'other'}
 
     with context_decorator as cassette:
         assert cassette._path == 'other'
 
-    arg_getter.return_value = ('', {'filter_headers': ('header_name',)})
+    arg_getter.return_value = {'path': 'other', 'filter_headers': ('header_name',)}
 
     @context_decorator
     def function():
         pass
 
-    with mock.patch.object(Cassette, 'load', return_value=mock.MagicMock(inject=False)) as cassette_load:
+    with mock.patch.object(
+        Cassette, 'load',
+        return_value=mock.MagicMock(inject=False)
+    ) as cassette_load:
         function()
-        cassette_load.assert_called_once_with(arg_getter.return_value[0],
-                                              **arg_getter.return_value[1])
+        cassette_load.assert_called_once_with(**arg_getter.return_value)
 
 
 def test_cassette_not_all_played():
@@ -156,13 +159,13 @@ def test_nesting_cassette_context_managers(*args):
     second_response['body']['string'] = b'second_response'
 
     with contextlib2.ExitStack() as exit_stack:
-        first_cassette = exit_stack.enter_context(Cassette.use('test'))
+        first_cassette = exit_stack.enter_context(Cassette.use(path='test'))
         exit_stack.enter_context(mock.patch.object(first_cassette, 'play_response',
                                                     return_value=first_response))
         assert_get_response_body_is('first_response')
 
         # Make sure a second cassette can supercede the first
-        with Cassette.use('test') as second_cassette:
+        with Cassette.use(path='test') as second_cassette:
             with mock.patch.object(second_cassette, 'play_response', return_value=second_response):
                 assert_get_response_body_is('second_response')
 
@@ -172,12 +175,12 @@ def test_nesting_cassette_context_managers(*args):
 
 def test_nesting_context_managers_by_checking_references_of_http_connection():
     original = httplib.HTTPConnection
-    with Cassette.use('test'):
+    with Cassette.use(path='test'):
         first_cassette_HTTPConnection = httplib.HTTPConnection
-        with Cassette.use('test'):
+        with Cassette.use(path='test'):
             second_cassette_HTTPConnection = httplib.HTTPConnection
             assert second_cassette_HTTPConnection is not first_cassette_HTTPConnection
-            with Cassette.use('test'):
+            with Cassette.use(path='test'):
                 assert httplib.HTTPConnection is not second_cassette_HTTPConnection
                 with force_reset():
                     assert httplib.HTTPConnection is original
@@ -188,12 +191,14 @@ def test_nesting_context_managers_by_checking_references_of_http_connection():
 def test_custom_patchers():
     class Test(object):
         attribute = None
-    with Cassette.use('custom_patches', custom_patches=((Test, 'attribute', VCRHTTPSConnection),)):
+    with Cassette.use(path='custom_patches',
+                      custom_patches=((Test, 'attribute', VCRHTTPSConnection),)):
         assert issubclass(Test.attribute, VCRHTTPSConnection)
         assert VCRHTTPSConnection is not Test.attribute
         old_attribute = Test.attribute
 
-        with Cassette.use('custom_patches', custom_patches=((Test, 'attribute', VCRHTTPSConnection),)):
+        with Cassette.use(path='custom_patches',
+                          custom_patches=((Test, 'attribute', VCRHTTPSConnection),)):
             assert issubclass(Test.attribute, VCRHTTPSConnection)
             assert VCRHTTPSConnection is not Test.attribute
             assert  Test.attribute is not old_attribute
@@ -203,10 +208,10 @@ def test_custom_patchers():
         assert  Test.attribute is old_attribute
 
 
-def test_use_cassette_decorated_functions_are_reentrant():
+def test_decorated_functions_are_reentrant():
     info = {"second": False}
     original_conn = httplib.HTTPConnection
-    @Cassette.use('whatever', inject=True)
+    @Cassette.use(path='whatever', inject=True)
     def test_function(cassette):
         if info['second']:
             assert httplib.HTTPConnection is not info['first_conn']
@@ -217,3 +222,35 @@ def test_use_cassette_decorated_functions_are_reentrant():
             assert httplib.HTTPConnection is info['first_conn']
     test_function()
     assert httplib.HTTPConnection is original_conn
+
+
+def test_cassette_use_called_without_path_uses_function_to_generate_path():
+    @Cassette.use(inject=True)
+    def function_name(cassette):
+        assert cassette._path == 'function_name'
+    function_name()
+
+
+def test_path_transformer_with_function_path():
+    path_transformer = lambda path: os.path.join('a', path)
+    @Cassette.use(inject=True, path_transformer=path_transformer)
+    def function_name(cassette):
+        assert cassette._path == os.path.join('a', 'function_name')
+    function_name()
+
+
+def test_path_transformer_with_context_manager():
+    with Cassette.use(
+        path='b', path_transformer=lambda *args: 'a'
+    ) as cassette:
+        assert cassette._path == 'a'
+
+
+def test_func_path_generator():
+    def generator(function):
+        return os.path.join(os.path.dirname(inspect.getfile(function)),
+                                            function.__name__)
+    @Cassette.use(inject=True, func_path_generator=generator)
+    def function_name(cassette):
+        assert cassette._path == os.path.join(os.path.dirname(__file__), 'function_name')
+    function_name()

tests/unit/test_vcr.py

@@ -1,3 +1,5 @@
+import os
+
 import mock
 import pytest
 
@@ -9,7 +11,10 @@ from vcr.stubs import VCRHTTPSConnection
 def test_vcr_use_cassette():
     record_mode = mock.Mock()
     test_vcr = VCR(record_mode=record_mode)
-    with mock.patch('vcr.cassette.Cassette.load', return_value=mock.MagicMock(inject=False)) as mock_cassette_load:
+    with mock.patch(
+        'vcr.cassette.Cassette.load',
+        return_value=mock.MagicMock(inject=False)
+    ) as mock_cassette_load:
         @test_vcr.use_cassette('test')
         def function():
             pass
@@ -87,7 +92,10 @@ def test_custom_patchers():
         assert issubclass(Test.attribute, VCRHTTPSConnection)
         assert VCRHTTPSConnection is not Test.attribute
 
-    with test_vcr.use_cassette('custom_patches', custom_patches=((Test, 'attribute2', VCRHTTPSConnection),)):
+    with test_vcr.use_cassette(
+        'custom_patches',
+        custom_patches=((Test, 'attribute2', VCRHTTPSConnection),)
+    ):
         assert issubclass(Test.attribute, VCRHTTPSConnection)
         assert VCRHTTPSConnection is not Test.attribute
         assert Test.attribute is Test.attribute2
@@ -128,3 +136,57 @@ def test_with_current_defaults():
     vcr.record_mode = 'all'
     changing_defaults(assert_record_mode_all)
     current_defaults(assert_record_mode_once)
+
+
+def test_cassette_library_dir_with_decoration_and_no_explicit_path():
+    library_dir = '/libary_dir'
+    vcr = VCR(inject_cassette=True, cassette_library_dir=library_dir)
+    @vcr.use_cassette()
+    def function_name(cassette):
+        assert cassette._path == os.path.join(library_dir, 'function_name')
+    function_name()
+
+
+def test_cassette_library_dir_with_path_transformer():
+    library_dir = '/libary_dir'
+    vcr = VCR(inject_cassette=True, cassette_library_dir=library_dir,
+              path_transformer=lambda path: path + '.json')
+    @vcr.use_cassette()
+    def function_name(cassette):
+        assert cassette._path == os.path.join(library_dir, 'function_name.json')
+    function_name()
+
+
+def test_use_cassette_with_no_extra_invocation():
+    vcr = VCR(inject_cassette=True, cassette_library_dir='/')
+    @vcr.use_cassette
+    def function_name(cassette):
+        assert cassette._path == os.path.join('/', 'function_name')
+    function_name()
+
+
+def test_path_transformer():
+    vcr = VCR(inject_cassette=True, cassette_library_dir='/',
+              path_transformer=lambda x: x + '_test')
+    @vcr.use_cassette
+    def function_name(cassette):
+        assert cassette._path == os.path.join('/', 'function_name_test')
+    function_name()
+
+
+def test_cassette_name_generator_defaults_to_using_module_function_defined_in():
+    vcr = VCR(inject_cassette=True)
+    @vcr.use_cassette
+    def function_name(cassette):
+        assert cassette._path == os.path.join(os.path.dirname(__file__),
+                                              'function_name')
+    function_name()
+
+
+def test_ensure_suffix():
+    vcr = VCR(inject_cassette=True, path_transformer=VCR.ensure_suffix('.yaml'))
+    @vcr.use_cassette
+    def function_name(cassette):
+        assert cassette._path == os.path.join(os.path.dirname(__file__),
+                                              'function_name.yaml')
+    function_name()

vcr/cassette.py

@@ -1,4 +1,5 @@
 """The container for recorded requests and responses"""
+import functools
 import logging
 
 import contextlib2
@@ -9,11 +10,12 @@ except ImportError:
     from backport_collections import Counter
 
 # Internal imports
+from .errors import UnhandledHTTPRequestError
+from .matchers import requests_match, uri, method
 from .patch import CassettePatcherBuilder
 from .persist import load_cassette, save_cassette
 from .serializers import yamlserializer
-from .matchers import requests_match, uri, method
-from .errors import UnhandledHTTPRequestError
+from .util import partition_dict
 
 
 log = logging.getLogger(__name__)
@@ -29,9 +31,11 @@ class CassetteContextDecorator(object):
     from interfering with another.
     """
 
+    _non_cassette_arguments = ('path_transformer', 'func_path_generator')
+
     @classmethod
-    def from_args(cls, cassette_class, path, **kwargs):
-        return cls(cassette_class, lambda: (path, kwargs))
+    def from_args(cls, cassette_class, **kwargs):
+        return cls(cassette_class, lambda: dict(kwargs))
 
     def __init__(self, cls, args_getter):
         self.cls = cls
@@ -49,6 +53,14 @@ class CassetteContextDecorator(object):
             # somewhere else.
             cassette._save()
 
+    @classmethod
+    def key_predicate(cls, key, value):
+        return key in cls._non_cassette_arguments
+
+    @classmethod
+    def _split_keys(cls, kwargs):
+        return partition_dict(cls.key_predicate, kwargs)
+
     def __enter__(self):
         # This assertion is here to prevent the dangerous behavior
         # that would result from forgetting about a __finish before
@@ -59,8 +71,11 @@ class CassetteContextDecorator(object):
         #     with context_decorator:
         #         pass
         assert self.__finish is None, "Cassette already open."
-        path, kwargs = self._args_getter()
-        self.__finish = self._patch_generator(self.cls.load(path, **kwargs))
+        other_kwargs, cassette_kwargs = self._split_keys(self._args_getter())
+        if 'path_transformer' in other_kwargs:
+            transformer = other_kwargs['path_transformer']
+            cassette_kwargs['path'] = transformer(cassette_kwargs['path'])
+        self.__finish = self._patch_generator(self.cls.load(**cassette_kwargs))
         return next(self.__finish)
 
     def __exit__(self, *args):
@@ -70,23 +85,42 @@ class CassetteContextDecorator(object):
     @wrapt.decorator
     def __call__(self, function, instance, args, kwargs):
         # This awkward cloning thing is done to ensure that decorated
-        # functions are reentrant. Reentrancy is required for thread
+        # functions are reentrant. This is required for thread
         # safety and the correct operation of recursive functions.
-        clone = type(self)(self.cls, self._args_getter)
+        args_getter = self._build_args_getter_for_decorator(
+            function, self._args_getter
+        )
+        clone = type(self)(self.cls, args_getter)
         with clone as cassette:
             if cassette.inject:
                 return function(cassette, *args, **kwargs)
             else:
                 return function(*args, **kwargs)
 
+    @staticmethod
+    def get_function_name(function):
+        return function.__name__
+
+    @classmethod
+    def _build_args_getter_for_decorator(cls, function, args_getter):
+        def new_args_getter():
+            kwargs = args_getter()
+            if 'path' not in kwargs:
+                name_generator = (kwargs.get('func_path_generator') or
+                                  cls.get_function_name)
+                path = name_generator(function)
+                kwargs['path'] = path
+            return kwargs
+        return new_args_getter
+
 
 class Cassette(object):
     """A container for recorded requests and responses"""
 
     @classmethod
-    def load(cls, path, **kwargs):
+    def load(cls, **kwargs):
         """Instantiate and load the cassette stored at the specified path."""
-        new_cassette = cls(path, **kwargs)
+        new_cassette = cls(**kwargs)
         new_cassette._load()
         return new_cassette
 
@@ -95,8 +129,8 @@ class Cassette(object):
         return CassetteContextDecorator(cls, arg_getter)
 
     @classmethod
-    def use(cls, *args, **kwargs):
-        return CassetteContextDecorator.from_args(cls, *args, **kwargs)
+    def use(cls, **kwargs):
+        return CassetteContextDecorator.from_args(cls, **kwargs)
 
     def __init__(self, path, serializer=yamlserializer, record_mode='once',
                  match_on=(uri, method),  before_record_request=None,

vcr/config.py

@@ -1,23 +1,35 @@
 import collections
 import copy
 import functools
+import inspect
 import os
 
+import six
+
 from .cassette import Cassette
 from .serializers import yamlserializer, jsonserializer
+from .util import compose
 from . import matchers
 from . import filters
 
 
 class VCR(object):
 
-    def __init__(self, serializer='yaml', cassette_library_dir=None,
-                 record_mode="once", filter_headers=(), ignore_localhost=False,
-                 custom_patches=(), filter_query_parameters=(),
-                 filter_post_data_parameters=(), before_record_request=None,
-                 before_record_response=None, ignore_hosts=(),
+    @staticmethod
+    def ensure_suffix(suffix):
+        def ensure(path):
+            if not path.endswith(suffix):
+                return path + suffix
+            return path
+        return ensure
+
+    def __init__(self, path_transformer=lambda x: x, before_record_request=None,
+                 custom_patches=(), filter_query_parameters=(), ignore_hosts=(),
+                 record_mode="once", ignore_localhost=False, filter_headers=(),
+                 before_record_response=None, filter_post_data_parameters=(),
                  match_on=('method', 'scheme', 'host', 'port', 'path', 'query'),
-                 before_record=None, inject_cassette=False):
+                 before_record=None, inject_cassette=False, serializer='yaml',
+                 cassette_library_dir=None, func_path_generator=None):
         self.serializer = serializer
         self.match_on = match_on
         self.cassette_library_dir = cassette_library_dir
@@ -46,6 +58,8 @@ class VCR(object):
         self.ignore_hosts = ignore_hosts
         self.ignore_localhost = ignore_localhost
         self.inject_cassette = inject_cassette
+        self.path_transformer = path_transformer
+        self.func_path_generator = func_path_generator
         self._custom_patches = tuple(custom_patches)
 
     def _get_serializer(self, serializer_name):
@@ -69,27 +83,48 @@ class VCR(object):
             )
         return matchers
 
-    def use_cassette(self, path, with_current_defaults=False, **kwargs):
+    def use_cassette(self, path=None, **kwargs):
+        if path is not None and not isinstance(path, six.string_types):
+            function = path
+            # Assume this is an attempt to decorate a function
+            return self._use_cassette(**kwargs)(function)
+        return self._use_cassette(path=path, **kwargs)
+
+    def _use_cassette(self, with_current_defaults=False, **kwargs):
         if with_current_defaults:
-            path, config = self.get_path_and_merged_config(path, **kwargs)
-            return Cassette.use(path, **config)
+            config = self.get_merged_config(**kwargs)
+            return Cassette.use(**config)
         # This is made a function that evaluates every time a cassette
         # is made so that changes that are made to this VCR instance
         # that occur AFTER the `use_cassette` decorator is applied
         # still affect subsequent calls to the decorated function.
-        args_getter = functools.partial(self.get_path_and_merged_config,
-                                        path, **kwargs)
+        args_getter = functools.partial(self.get_merged_config, **kwargs)
         return Cassette.use_arg_getter(args_getter)
 
-    def get_path_and_merged_config(self, path, **kwargs):
+    def get_merged_config(self, **kwargs):
         serializer_name = kwargs.get('serializer', self.serializer)
         matcher_names = kwargs.get('match_on', self.match_on)
+        path_transformer = kwargs.get(
+            'path_transformer',
+            self.path_transformer
+        )
+        func_path_generator = kwargs.get(
+            'func_path_generator',
+            self.func_path_generator
+        )
         cassette_library_dir = kwargs.get(
             'cassette_library_dir',
             self.cassette_library_dir
         )
         if cassette_library_dir:
-            path = os.path.join(cassette_library_dir, path)
+            def add_cassette_library_dir(path):
+                if not path.startswith(cassette_library_dir):
+                    return os.path.join(cassette_library_dir, path)
+            path_transformer = compose(add_cassette_library_dir, path_transformer)
+        elif not func_path_generator:
+            # If we don't have a library dir, use the functions
+            # location to build a full path for cassettes.
+            func_path_generator = self._build_path_from_func_using_module
 
         merged_config = {
             'serializer': self._get_serializer(serializer_name),
@@ -102,9 +137,14 @@ class VCR(object):
             'custom_patches': self._custom_patches + kwargs.get(
                 'custom_patches', ()
             ),
-            'inject': kwargs.get('inject_cassette', self.inject_cassette)
+            'inject': kwargs.get('inject_cassette', self.inject_cassette),
+            'path_transformer': path_transformer,
+            'func_path_generator': func_path_generator
         }
-        return path, merged_config
+        path = kwargs.get('path')
+        if path:
+            merged_config['path'] = path
+        return merged_config
 
     def _build_before_record_response(self, options):
         before_record_response = options.get(
@@ -185,6 +225,11 @@ class VCR(object):
             return request
         return filter_ignored_hosts
 
+    @staticmethod
+    def _build_path_from_func_using_module(function):
+        return os.path.join(os.path.dirname(inspect.getfile(function)),
+                                            function.__name__)
+
     def register_serializer(self, name, serializer):
         self.serializers[name] = serializer
 

vcr/util.py

@@ -0,0 +1,16 @@
+def partition_dict(predicate, dictionary):
+    true_dict = {}
+    false_dict = {}
+    for key, value in dictionary.items():
+        this_dict = true_dict if predicate(key, value) else false_dict
+        this_dict[key] = value
+    return true_dict, false_dict
+
+
+def compose(*functions):
+    def composed(incoming):
+        res = incoming
+        for function in functions[::-1]:
+            res = function(res)
+        return res
+    return composed