Github user pnowojski commented on a diff in the pull request: https://github.com/apache/flink/pull/4649#discussion_r161799248 --- Diff: flink-streaming-java/src/test/java/org/apache/flink/streaming/api/DataStreamTest.java --- @@ -183,6 +183,14 @@ public Long map(Long value) throws Exception { // verify self union assertTrue(streamGraph.getStreamNode(selfUnion.getId()).getInEdges().size() == 2); + assertTrue(streamGraph.getUniqueEdgeMap().size() == 12); --- End diff -- Can not it be tested otherwise? This test shouldn't have an access to `getUniqueEdgeMap()` since that should be a part of the private implementation. If one chooses to implement this feature differently, this test would brake. Can not this test just check that `org.apache.flink.streaming.api.graph.StreamGraph#getStreamEdges(selfUnion.getId(), selfUnion.getId())` contains two unique edges? Side note, shouldn't the `getStreamEdges()` return a `Set<StreamEdge>` instead of `List`?
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