As you doesn't setup the route of mock://vm:restQuery, you may consider to add the route like this into your camel context before running the test.
Or you can use the interceptSendToEndpoint() DSL to simulate the response from the processor. You can find more example in the Camel in Action Chapter6.
Thanks. The solution was to remove any reference and use of mocks and use the interceptSendToEndpoint on the vm:restQuery endpoint to return the value.