Fix test for empty resources response

Update test_resources_returns_empty_array_when_no_resources to use
correct mock response format with empty resources array instead of
empty result object. Also reorder test to group with other resources
tests.

Follow up: https://github.com/modelcontextprotocol/ruby-sdk/pull/160

test/mcp/client_test.rb

@@ -84,6 +84,18 @@ module MCP
       assert_equal("file:///path/to/resource2", resources.last["uri"])
     end
 
+    def test_resources_returns_empty_array_when_no_resources
+      transport = mock
+      mock_response = { "result" => { "resources" => [] } }
+
+      transport.expects(:send_request).returns(mock_response).once
+
+      client = Client.new(transport: transport)
+      resources = client.resources
+
+      assert_empty(resources)
+    end
+
     def test_read_resource_sends_request_to_transport_and_returns_contents
       transport = mock
       uri = "file:///path/to/resource.txt"
@@ -129,17 +141,5 @@ module MCP
 
       assert_empty(contents)
     end
-
-    def test_resources_returns_empty_array_when_no_resources
-      transport = mock
-      mock_response = { "result" => {} }
-
-      transport.expects(:send_request).returns(mock_response).once
-
-      client = Client.new(transport: transport)
-      resources = client.resources
-
-      assert_empty(resources)
-    end
   end
 end