Updated test of application of hint so that it works with MongoDB 3.2 sharded clusters, in which the explain plan output has changed slightly.

Author: jyemin

driver/src/test/functional/com/mongodb/DBCursorFunctionalSpecification.groovy

@@ -74,15 +74,17 @@ class DBCursorFunctionalSpecification extends FunctionalSpecification {
 
         when:
         dbCursor = collection.find().hint(new BasicDBObject('a', 1))
+        def explainPlan = dbCursor.explain()
 
         then:
-        dbCursor.explain().queryPlanner.winningPlan.inputStage.keyPattern == cursorMap
+        getKeyPattern(explainPlan) == cursorMap
 
         when:
         dbCursor = collection.find().addSpecial('$hint', new BasicDBObject('a', 1))
+        explainPlan = dbCursor.explain()
 
         then:
-        dbCursor.explain().queryPlanner.winningPlan.inputStage.keyPattern == cursorMap
+        getKeyPattern(explainPlan) == cursorMap
     }
 
     def 'should use provided hint for count'() {
@@ -118,15 +120,17 @@ class DBCursorFunctionalSpecification extends FunctionalSpecification {
 
         when:
         dbCursor = collection.find().hint('a_1')
+        def explainPlan = dbCursor.explain()
 
         then:
-        dbCursor.explain().queryPlanner.winningPlan.inputStage.keyPattern == cursorMap
+        getKeyPattern(explainPlan) == cursorMap
 
         when:
         dbCursor = collection.find().addSpecial('$hint', 'a_1')
+        explainPlan = dbCursor.explain()
 
         then:
-        dbCursor.explain().queryPlanner.winningPlan.inputStage.keyPattern == cursorMap
+        getKeyPattern(explainPlan) == cursorMap
     }
 
     def 'should use provided hints for count'() {
@@ -209,9 +213,10 @@ class DBCursorFunctionalSpecification extends FunctionalSpecification {
         when:
         dbCursor = collection.find().hint(new BasicDBObject('a', 1))
         dbCursor.addSpecial('$explain', 1)
+        def explainPlan = dbCursor.explain()
 
         then:
-        dbCursor.explain().queryPlanner.winningPlan.inputStage.keyPattern == cursorMap
+        getKeyPattern(explainPlan) == cursorMap
     }
 
 
@@ -372,4 +377,12 @@ class DBCursorFunctionalSpecification extends FunctionalSpecification {
         then:
         executor.getReadPreference() == ReadPreference.secondaryPreferred()
     }
+
+    static DBObject getKeyPattern(DBObject explainPlan) {
+        if (explainPlan.queryPlanner.winningPlan.inputStage != null) {
+            return explainPlan.queryPlanner.winningPlan.inputStage.keyPattern
+        } else if (explainPlan.queryPlanner.winningPlan.shards != null) {
+            return explainPlan.queryPlanner.winningPlan.shards[0].winningPlan.inputStage.keyPattern
+        }
+    }
 }