GODRIVER-1021 specify behavior when URI has auth database but no credentials

Change-Id: Ib3d07fea98402f680a2c1adddae5708005e7b7d7

Author: iwysiu

data/auth/README.rst

@@ -0,0 +1,53 @@
+==========
+Auth Tests
+==========
+
+The YAML and JSON files in this directory tree are platform-independent tests
+that drivers can use to prove their conformance to the Auth Spec at least with
+respect to connection string URI input.
+
+Drivers should do additional unit testing if there are alternate ways of
+configuring credentials on a client.
+
+Driver must also conduct the prose tests in the Auth Spec test plan section.
+
+Format
+------
+
+Each YAML file contains an object with a single ``tests`` key. This key is an
+array of test case objects, each of which have the following keys:
+
+- ``description``: A string describing the test.
+- ``uri``: A string containing the URI to be parsed.
+- ``valid:`` A boolean indicating if the URI should be considered valid.
+- ``credential``: If null, the credential must not be considered configured for the
+  the purpose of deciding if the driver should authenticate to the topology.  If non-null,
+  it is an object containing one or more of the following properties of a credential:
+
+  - ``username``: A string containing the username. For auth mechanisms
+    that do not utilize a password, this may be the entire ``userinfo`` token
+    from the connection string.
+  - ``password``: A string containing the password.
+  - ``source``: A string containing the authentication database.
+  - ``mechanism``: A string containing the authentication mechanism.  A null value for
+    this key is used to indicate that a mechanism wasn't specified and that mechanism
+    negotiation is required.  Test harnesses should modify the mechanism test as needed
+    to assert this condition.
+  - ``mechanism_properties``: A document containing mechanism-specific properties.  It
+    specifies a subset of properties that must match.  If a key exists in the test data,
+    it must exist with the corresponding value in the credential.  Other values may
+    exist in the credential without failing the test.
+
+If any key is missing, no assertion about that key is necessary.  Except as
+specified explicitly above, if a key is present, but the test value is null,
+the observed value for that key must be uninitialized (whatever that means for
+a given driver and data type).
+
+Implementation notes
+====================
+
+Testing whether a URI is valid or not should simply be a matter of checking
+whether URI parsing (or MongoClient construction) raises an error or exception.
+
+If a credential is configured, its properties must be compared to the
+``credential`` field.