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.

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):