panic in describeconfigs merge when unknown type is received

Author: rhansen2

protocol/describeconfigs/describeconfigs.go

@@ -99,7 +99,7 @@ func (r *Response) Merge(requests []protocol.Message, results []interface{}) (
 			return nil, v
 
 		default:
-			return nil, fmt.Errorf("Unknown result type: %T", result)
+			panic(fmt.Sprintf("unknown result type in Merge: %T", result))
 		}
 	}
 
@@ -132,6 +132,4 @@ type ResponseConfigSynonym struct {
 	ConfigSource int8   `kafka:"min=v1,max=v3"`
 }
 
-var (
-	_ protocol.BrokerMessage = (*Request)(nil)
-)
+var _ protocol.BrokerMessage = (*Request)(nil)

protocol/describeconfigs/describeconfigs_test.go

@@ -54,4 +54,23 @@ func TestResponse_Merge(t *testing.T) {
 			t.Fatalf("wanted err io.EOF, got %v", err)
 		}
 	})
+
+	t.Run("panic with unexpected type", func(t *testing.T) {
+		defer func() {
+			msg := recover()
+			if msg != "unknown result type in Merge: string" {
+				t.Fatal("unexpected panic", msg)
+			}
+		}()
+		r := &Response{}
+
+		r1 := &Response{
+			Resources: []ResponseResource{
+				{ResourceName: "r1"},
+			},
+		}
+
+		_, _ = r.Merge([]protocol.Message{&Request{}}, []interface{}{r1, "how did a string got here"})
+		t.Fatal("did not panic")
+	})
 }