HashMap with Enum as key - test generation fails

[alisevych]

Description

Test generation fails for a method with HashMap using Enum as key.

To Reproduce

Steps to reproduce the behavior:

1. IntelliJ IDEA with UTBotJava plugin installed
2. A project with JDK 8/11 is opened
3. Add the following class:

public class MapWithEnum {

    public void createMapWithEnum() {
        Map<WorkDays, Integer> map = new HashMap<>();
        map.put(WorkDays.Monday, 112);
        map.put(WorkDays.Tuesday, 354);
        map.put(WorkDays.Friday, 567);
        map.remove(WorkDays.Tuesday);
    }

    public enum WorkDays {
        Monday,
        Tuesday,
        Wednesday,
        Thursday,
        Friday
    }
}

4. Run Generating tests with UTBot... for this class

Expected behavior

Tests are supposed to be generated.

Actual behavior

"Failed to generate unit tests for class MapWithEnum" error popup is shown in IDEA.
It is shown immediately after test generation is started.
Map.remove() method is crucial for the issue - without it generation passes.

Visual proofs (screenshots, logs, images)

Environment

Windows 10 Pro
IntelliJ IDEA 2022.1.3
checked on JDK 8 and 11, Gradle, Maven projects - same error

Additional context

Adding some input parameters to the method helps - fuzzer is generating tests.

Map.remove() method is crucial for the issue - without it generation passes.

Map with Enum as values - test generation passes.

[dtim]

Related to #230, #414

[dtim]

It seems that the problem is not enum-specific. The following example does not work as well:

    public HashMap<String, Integer> createMapWithString() {
        HashMap<String, Integer> map = new HashMap<>();
        map.put("tuesday", 354);
        map.remove("tuesday");
        return map;
    }

[CaelmBleidd]

Looks like it doesn't work when key and value have different types. Following examples doesn't work as well:

Integer mapPutAndGet() {
  Map<Long, Integer> values = new HashMap<>();

  values.put(new Long(1), new Integer(1));

  return values.get(new Long(1));
}