change all the matchers with an assert statement and refactor the requests_match function

In order to use the new assert mechanism that returns explicit assertion failure message, all the default matchers does not return a boolean, but only do an assert statement with a basic assertion message (value_1 != value_2).
The requests_match function has been refactored to use the 'get_matchers_results' function in order to have explicit failures that are logged if any.
Many unit tests have been changed as the matchers does not return a boolean value anymore.
Note: Only the matchers "body" and "raw_body" does not have an assertion message, the body values might be big and not useful to be display to spot the differences.

tests/unit/test_matchers.py

@@ -1,4 +1,5 @@
 import itertools
+from vcr.compat import mock
 
 import pytest
 
@@ -21,20 +22,22 @@ REQUESTS = {
 def assert_matcher(matcher_name):
     matcher = getattr(matchers, matcher_name)
     for k1, k2 in itertools.permutations(REQUESTS, 2):
-        matched = matcher(REQUESTS[k1], REQUESTS[k2])
-        if matcher_name in {k1, k2}:
-            assert not matched
+        expecting_assertion_error = matcher_name in {k1, k2}
+        if expecting_assertion_error:
+            with pytest.raises(AssertionError):
+                matcher(REQUESTS[k1], REQUESTS[k2])
         else:
-            assert matched
+            assert matcher(REQUESTS[k1], REQUESTS[k2]) is None
 
 
 def test_uri_matcher():
     for k1, k2 in itertools.permutations(REQUESTS, 2):
-        matched = matchers.uri(REQUESTS[k1], REQUESTS[k2])
-        if {k1, k2} != {'base', 'method'}:
-            assert not matched
+        expecting_assertion_error = {k1, k2} != {"base", "method"}
+        if expecting_assertion_error:
+            with pytest.raises(AssertionError):
+                matchers.uri(REQUESTS[k1], REQUESTS[k2])
         else:
-            assert matched
+            assert matchers.uri(REQUESTS[k1], REQUESTS[k2]) is None
 
 
 req1_body = (b"<?xml version='1.0'?><methodCall><methodName>test</methodName>"
@@ -107,7 +110,7 @@ req2_body = (b"<?xml version='1.0'?><methodCall><methodName>test</methodName>"
     )
 ])
 def test_body_matcher_does_match(r1, r2):
-    assert matchers.body(r1, r2)
+    assert matchers.body(r1, r2) is None
 
 
 @pytest.mark.parametrize("r1, r2", [
@@ -135,13 +138,30 @@ def test_body_matcher_does_match(r1, r2):
     )
 ])
 def test_body_match_does_not_match(r1, r2):
-    assert not matchers.body(r1, r2)
+    with pytest.raises(AssertionError):
+        matchers.body(r1, r2)
 
 
 def test_query_matcher():
-    req1 = request.Request('GET', 'http://host.com/?a=b&c=d', '', {})
-    req2 = request.Request('GET', 'http://host.com/?c=d&a=b', '', {})
-    assert matchers.query(req1, req2)
+    req1 = request.Request("GET", "http://host.com/?a=b&c=d", "", {})
+    req2 = request.Request("GET", "http://host.com/?c=d&a=b", "", {})
+    assert matchers.query(req1, req2) is None
+
+    req1 = request.Request("GET", "http://host.com/?a=b&a=b&c=d", "", {})
+    req2 = request.Request("GET", "http://host.com/?a=b&c=d&a=b", "", {})
+    req3 = request.Request("GET", "http://host.com/?c=d&a=b&a=b", "", {})
+    assert matchers.query(req1, req2) is None
+    assert matchers.query(req1, req3) is None
+
+
+def test_matchers():
+    assert_matcher("method")
+    assert_matcher("scheme")
+    assert_matcher("host")
+    assert_matcher("port")
+    assert_matcher("path")
+    assert_matcher("query")
+
 
 def test_evaluate_matcher_does_match():
     def bool_matcher(r1, r2):
@@ -230,3 +250,20 @@ def test_get_matchers_results(r1, r2, expected_successes, expected_failures):
     for i, expected_failure in enumerate(expected_failures):
         assert failures[i][0] == expected_failure
         assert failures[i][1] is not None
+
+
+@mock.patch("vcr.matchers.get_matchers_results")
+@pytest.mark.parametrize(
+    "successes, failures, expected_match",
+    [
+        (["method", "path"], [], True),
+        (["method"], ["path"], False),
+        ([], ["method", "path"], False),
+    ],
+)
+def test_requests_match(mock_get_matchers_results, successes, failures, expected_match):
+    mock_get_matchers_results.return_value = (successes, failures)
+    r1 = request.Request("GET", "http://host.com/p?a=b", "", {})
+    r2 = request.Request("GET", "http://host.com/p?a=b", "", {})
+    match = matchers.requests_match(r1, r2, [matchers.method, matchers.path])
+    assert match is expected_match

vcr/matchers.py

@@ -8,35 +8,47 @@ log = logging.getLogger(__name__)
 
 
 def method(r1, r2):
-    return r1.method == r2.method
+    assert r1.method == r2.method, "{} != {}".format(r1.method, r2.method)
 
 
 def uri(r1, r2):
-    return r1.uri == r2.uri
+    assert r1.uri == r2.uri, "{} != {}".format(r1.uri, r2.uri)
 
 
 def host(r1, r2):
-    return r1.host == r2.host
+    assert r1.host == r2.host, "{} != {}".format(r1.host, r2.host)
 
 
 def scheme(r1, r2):
-    return r1.scheme == r2.scheme
+    assert r1.scheme == r2.scheme, "{} != {}".format(r1.scheme, r2.scheme)
 
 
 def port(r1, r2):
-    return r1.port == r2.port
+    assert r1.port == r2.port, "{} != {}".format(r1.port, r2.port)
 
 
 def path(r1, r2):
-    return r1.path == r2.path
+    assert r1.path == r2.path, "{} != {}".format(r1.path, r2.path)
 
 
 def query(r1, r2):
-    return r1.query == r2.query
+    assert r1.query == r2.query, "{} != {}".format(r1.query, r2.query)
 
 
 def raw_body(r1, r2):
-    return read_body(r1) == read_body(r2)
+    assert read_body(r1) == read_body(r2)
+
+
+def body(r1, r2):
+    transformer = _get_transformer(r1)
+    r2_transformer = _get_transformer(r2)
+    if transformer != r2_transformer:
+        transformer = _identity
+    assert transformer(read_body(r1)) == transformer(read_body(r2))
+
+
+def headers(r1, r2):
+    assert r1.headers == r2.headers, "{} != {}".format(r1.headers, r2.headers)
 
 
 def _header_checker(value, header='Content-Type'):
@@ -74,31 +86,15 @@ def _get_transformer(request):
         return _identity
 
 
-def body(r1, r2):
-    transformer = _get_transformer(r1)
-    r2_transformer = _get_transformer(r2)
-    if transformer != r2_transformer:
-        transformer = _identity
-    return transformer(read_body(r1)) == transformer(read_body(r2))
-
-
-def headers(r1, r2):
-    return r1.headers == r2.headers
-
-
-def _log_matches(r1, r2, matches):
-    differences = [m for m in matches if not m[0]]
-    if differences:
-        log.debug(
-            "Requests {} and {} differ according to "
-            "the following matchers: {}".format(r1, r2, differences)
-        )
-
-
 def requests_match(r1, r2, matchers):
-    matches = [(m(r1, r2), m) for m in matchers]
-    _log_matches(r1, r2, matches)
-    return all(m[0] for m in matches)
+    successes, failures = get_matchers_results(r1, r2, matchers)
+    if failures:
+        log.debug(
+            "Requests {} and {} differ.\n"
+            "Failure details:\n"
+            "{}".format(r1, r2, failures)
+        )
+    return len(failures) == 0
 
 
 def _evaluate_matcher(matcher_function, *args):