Flaky test CriteriaUnitTests#shouldCreateIsInSet and a proposed fix

[LeoYimingLi]

• The flakiness in CriteriaUnitTests#shouldCreateIsInSet

  spring-data-cassandra/spring-data-cassandra/src/test/java/org/springframework/data/cassandra/core/query/CriteriaUnitTests.java

  Lines 113 to 119 in 880787f

  	@Test // DATACASS-343
  	void shouldCreateIsInSet() {
  	CriteriaDefinition criteria = Criteria.where("foo").in(new HashSet<>(Arrays.asList("a", "b", "c")));
  	assertThat(serializeToCqlSafely(criteria)).isEqualTo("foo IN {'a','b','c'}");
  	}

  is due to the nondeterministic iteration order of HashSet.

  spring-data-cassandra/spring-data-cassandra/src/main/java/org/springframework/data/cassandra/core/query/SerializationUtils.java

  Lines 115 to 118 in 880787f

  	private static String toString(Set<?> source) {
  	return iterableToDelimitedString(source, "{", "}",
  	(Converter<Object, Object>) SerializationUtils::serializeToCqlSafely);
  	}

  spring-data-cassandra/spring-data-cassandra/src/main/java/org/springframework/data/cassandra/core/query/SerializationUtils.java

  Lines 130 to 134 in 880787f

  	private static <T> String iterableToDelimitedString(Iterable<T> source, String prefix, String postfix,
  	Converter<? super T, Object> transformer) {
  	StringBuilder builder = new StringBuilder(prefix);
  	Iterator<T> iterator = source.iterator();

• We can include all the possible iteration order into consideration to fix the flakiness. Tentative PR: https://github.com/LeoYimingLi/spring-data-cassandra/pull/2/files

• version of spring data
  SHA: 880787f

• JVM version

  openjdk version "1.8.0_292"
  OpenJDK Runtime Environment (build 1.8.0_292-8u292-b10-0ubuntu1~18.04-b10)
  OpenJDK 64-Bit Server VM (build 25.292-b10, mixed mode)

• The way to reproduce the flaky test failure:

  • 0.Environment setup: Maven 3.6.0 and Java 1.8.0_292
  • 1.clone the repo:

  git clone https://github.com/spring-projects/spring-data-cassandra
  cd spring-data-cassandra
  git checkout 880787ff8841b461c3bff6d0755a485171867a59
  

  • 2.run with Nondex tool (which explores different behaviors of under-determined APIs and reports test failures)

  mvn install -pl spring-data-cassandra -am -DskipTests
  mvn -pl spring-data-cassandra edu.illinois:nondex-maven-plugin:1.1.2:debug -Dtest=spring-data-cassandra,org.springframework.data.cassandra.core.query.CriteriaUnitTests#shouldCreateIsInSet
  

  • 3.And we can get the test failure screenshot:
    

[mp911de]

Changing the set to a LinkedHashSet preserves iteration order unless the sets encounters duplicate items.

[LeoYimingLi]

get it, thank you.
I think this pr fixed in the suggested way: #1199