Confusion over when to use linear/forked

I am a little perplexed over when it is appropriate to call fork or linear.

I have called map2.forked before I then call map2.linear to create map3, however I see changes made to my map3 reflected in my map2. I had thought that forked would mean that changes to map3 don’t affect map2.

It may be that I have misunderstood the docs and this isn’t a bug after all. Some guidance would be appreciated please…

    @Test
    public void bifurcanImmutableRemoveThenRemove() {

        /*
          1. Create the initial map1: `map { 1: true(), 2: true() }`
         */
        IMap<Integer, Boolean> map1 = new LinearMap<>();
        map1.put(1, true);
        map1.put(2, true);
        map1 = map1.forked();  // make the map immutable
        checkMapIsForked(map1);

        /*
          2. Create map2 and remove the entry with key `2`
         */
        IMap<Integer, Boolean> map2 = map1.linear();  // create a transient map for modifications
        map2 = map2.remove(2);
        map2 = map2.forked();  // make the map immutable
        checkMapIsForked(map2);

        /*
          3. Check the entries in map2 with key `1` and `2`
         */
        final Boolean expected1 = map2.get(1, null);
        assertTrue(expected1);
        final Boolean expected2 = map2.get(2, null);
        assertNull(expected2);

        /*
         4. Create map3 and remove the entry in the with key `1`
         */
        IMap<Integer, Boolean> map3 = map2.linear();  // create a transient map for modifications
        map3 = map3.remove(1);
        map3 = map3.forked();  // make the map immutable
        checkMapIsForked(map3);

        /*
         I expect map2.get(1, null) to return true
        */
        assertEquals(expected1, map2.get(1, null));

        /*
         I expect map3.get(1, null) to return null
         */
        assertNotEquals(expected1, map3.get(1, null));
    }

[adamretter]

@ztellman Thanks for being so responsive as always Zach, it’s much appreciated. Also thanks for the prompt fix, I will upgrade our project to use it.

@line-o I believe that the code as I had it before is still correct, and that this fix resolves the issue we saw.

[ztellman]

This was an extremely indirect result of IntSet.isLinear always returning false due to it not being properly overridden. I’ve confirmed that your example now exhibits the correct behavior. Thanks for catching this, I need to give some thought as to properly expose these sorts of issues in my property-based testing.

I’ll update the issue once this fix is in a released version.