PYTHON-2183 Test that readPreferenceTags are always interpreted as an array

Also resolves PYTHON-2085.

test/uri_options/auth-options.json

@@ -1,7 +1,7 @@
 {
   "tests": [
     {
-      "description": "Valid auth options are parsed correctly",
+      "description": "Valid auth options are parsed correctly (GSSAPI)",
       "uri": "mongodb://foo:bar@example.com/?authMechanism=GSSAPI&authMechanismProperties=SERVICE_NAME:other,CANONICALIZE_HOST_NAME:true&authSource=$external",
       "valid": true,
       "warning": false,
@@ -15,6 +15,18 @@
         },
         "authSource": "$external"
       }
+    },
+    {
+      "description": "Valid auth options are parsed correctly (SCRAM-SHA-1)",
+      "uri": "mongodb://foo:bar@example.com/?authMechanism=SCRAM-SHA-1&authSource=authSourceDB",
+      "valid": true,
+      "warning": false,
+      "hosts": null,
+      "auth": null,
+      "options": {
+        "authMechanism": "SCRAM-SHA-1",
+        "authSource": "authSourceDB"
+      }
     }
   ]
 }

test/uri_options/concern-options.json

@@ -36,15 +36,6 @@
         "w": "arbitraryButStillValid"
       }
     },
-    {
-      "description": "Too low w causes a warning",
-      "uri": "mongodb://example.com/?w=-2",
-      "valid": true,
-      "warning": true,
-      "hosts": null,
-      "auth": null,
-      "options": {}
-    },
     {
       "description": "Non-numeric wTimeoutMS causes a warning",
       "uri": "mongodb://example.com/?wTimeoutMS=invalid",

test/uri_options/read-preference-options.json

@@ -21,6 +21,21 @@
         "maxStalenessSeconds": 120
       }
     },
+    {
+      "description": "Single readPreferenceTags is parsed as array of size one",
+      "uri": "mongodb://example.com/?readPreferenceTags=dc:ny",
+      "valid": true,
+      "warning": false,
+      "hosts": null,
+      "auth": null,
+      "options": {
+        "readPreferenceTags": [
+          {
+            "dc": "ny"
+          }
+        ]
+      }
+    },
     {
       "description": "Invalid readPreferenceTags causes a warning",
       "uri": "mongodb://example.com/?readPreferenceTags=invalid",