add cassette's method to find the most similar request(s) of a request

This method get the requests in the cassettes with the most matchers that succeeds.

tests/unit/test_cassettes.py

@@ -317,3 +317,51 @@ def test_use_as_decorator_on_generator():
         yield 2
 
     assert list(test_function()) == [1, 2]
+
+
+@mock.patch("vcr.cassette.get_matchers_results")
+def test_find_requests_with_most_matches_one_similar_request(mock_get_matchers_results):
+    mock_get_matchers_results.side_effect = [
+        (["method"], [("path", "failed : path"), ("query", "failed : query")]),
+        (["method", "path"], [("query", "failed : query")]),
+        ([], [("method", "failed : method"), ("path", "failed : path"), ("query", "failed : query")]),
+    ]
+
+    cassette = Cassette("test")
+    for request in range(1, 4):
+        cassette.append(request, 'response')
+    result = cassette.find_requests_with_most_matches("fake request")
+    assert result == [(2, ["method", "path"], [("query", "failed : query")])]
+
+
+@mock.patch("vcr.cassette.get_matchers_results")
+def test_find_requests_with_most_matches_no_similar_requests(mock_get_matchers_results):
+    mock_get_matchers_results.side_effect = [
+        ([], [("path", "failed : path"), ("query", "failed : query")]),
+        ([], [("path", "failed : path"), ("query", "failed : query")]),
+        ([], [("path", "failed : path"), ("query", "failed : query")]),
+    ]
+
+    cassette = Cassette("test")
+    for request in range(1, 4):
+        cassette.append(request, 'response')
+    result = cassette.find_requests_with_most_matches("fake request")
+    assert result == []
+
+
+@mock.patch("vcr.cassette.get_matchers_results")
+def test_find_requests_with_most_matches_many_similar_requests(mock_get_matchers_results):
+    mock_get_matchers_results.side_effect = [
+        (["method", "path"], [("query", "failed : query")]),
+        (["method"], [("path", "failed : path"), ("query", "failed : query")]),
+        (["method", "path"], [("query", "failed : query")]),
+    ]
+
+    cassette = Cassette("test")
+    for request in range(1, 4):
+        cassette.append(request, 'response')
+    result = cassette.find_requests_with_most_matches("fake request")
+    assert result == [
+        (1, ["method", "path"], [("query", "failed : query")]),
+        (3, ["method", "path"], [("query", "failed : query")])
+    ]

vcr/cassette.py

@@ -8,7 +8,7 @@ import wrapt
 
 from .compat import contextlib
 from .errors import UnhandledHTTPRequestError
-from .matchers import requests_match, uri, method
+from .matchers import requests_match, uri, method, get_matchers_results
 from .patch import CassettePatcherBuilder
 from .serializers import yamlserializer
 from .persisters.filesystem import FilesystemPersister
@@ -290,6 +290,38 @@ class Cassette(object):
     def rewind(self):
         self.play_counts = collections.Counter()
 
+    def find_requests_with_most_matches(self, request):
+        """
+        Get the most similar request(s) stored in the cassette
+        of a given request as a list of tuples like this:
+        - the request object
+        - the successful matchers as string
+        - the failed matchers and the related assertion message with the difference details as strings tuple
+
+        This is useful when a request failed to be found,
+        we can get the similar request(s) in order to know what have changed in the request parts.
+        """
+        best_matches = []
+        request = self._before_record_request(request)
+        for index, (stored_request, response) in enumerate(self.data):
+            successes, fails = get_matchers_results(request, stored_request, self._match_on)
+            best_matches.append((len(successes), stored_request, successes, fails))
+        best_matches.sort(key=lambda t: t[0], reverse=True)
+        # Get the first best matches (multiple if equal matches)
+        final_best_matches = []
+        previous_nb_success = best_matches[0][0]
+        for best_match in best_matches:
+            nb_success = best_match[0]
+            # Do not keep matches that have 0 successes,
+            # it means that the request is totally different from
+            # the ones stored in the cassette
+            if nb_success < 1 or previous_nb_success != nb_success:
+                break
+            previous_nb_success = nb_success
+            final_best_matches.append(best_match[1:])
+
+        return final_best_matches
+
     def _as_dict(self):
         return {"requests": self.requests, "responses": self.responses}