Iteration order can change when using `Columns.from(…)`

[LeoYimingLi]

• The flakiness in ColumnsUnitTests#shouldCreateFromColumns

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

  Lines 47 to 53 in 880787f

  	@Test // DATACASS-343
  	void shouldCreateFromColumns() {
  	Columns columns = Columns.from("asc", "bar");
  	assertThat(columns.toString()).isEqualTo("asc, bar");
  	}

  is due to the function Columns from(String... columnNames) where HashMap is used and the order of map is not guaranteed.
  

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

  Lines 69 to 78 in 880787f

  	public static Columns from(String... columnNames) {
  	Assert.notNull(columnNames, "Column names must not be null");
  	Map<ColumnName, Selector> columns = new HashMap<>(columnNames.length, 1);
  	Arrays.stream(columnNames)
  	.forEach(columnName -> columns.put(ColumnName.from(columnName), ColumnSelector.from(columnName)));
  	return new Columns(columns);

• We can use LinkedHashMap to replace HashMap to keep the order deterministic. Tentative PR to fix the flaky test: https://github.com/LeoYimingLi/spring-data-cassandra/pull/1/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:nondex -Dtest=org.springframework.data.cassandra.core.query.ColumnsUnitTests#shouldCreateFromColumns
  

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