[COLLECTIONS-802] ReferenceMap iterator remove violates contract

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 4.4
• Fix Version/s: 4.5.0-M1
• Component/s: Map
• Assignee: Bruno P. Kinoshita
• Reporter: Ben Manes
• Created: 31/Dec/21 05:43
• Updated: 28/Apr/22 10:39
• Resolved: 28/Apr/22 10:39

Description

Out of curiosity I ran Guava's testlib Map tests against the Apache types. This uncovered a contract bug where Iterator.remove() is invalidated by hasNext(), causing its call to no-op due to currentKey becoming null. The isolates case is,

@Test
public void iterator_remove() {
  var map = new ReferenceMap<>();
  map.put(1, 2);
  var iter = map.entrySet().iterator();
  assertTrue(iter.hasNext());
  assertTrue(iter.hasNext());
  assertEquals(iter.next(), 1);
  assertFalse(iter.hasNext());
  iter.remove();
  assertEquals(map, Map.of());
}

Guava's testlib has good coverage for the Collections Framework and might be worth integrating. The simple test case that I wrote is attached.

Issue Links

• links to: [COLLECTIONS-802] Fix remove failed by removing set null to currentKe… #300