Tests for MapDiff

[Akkihi]

Tests:

For <K, V> Map<K, V>.diff()

• Check that deletions, changing, additions are correct.
• Check that deletions, changing, additions are correct with compareFun.
• Check that deletions, changing, additions are correct with strictComparison.

For <K, V> MutableMap<K, V>.applyDiff()

• Check that deletions, changing, additions are correct.
• Check that deletions, changing, additions are correct with compareFun.
• Check that deletions, changing, additions are correct with strictComparison.

And additional mixed functions for general testing.

[InsanusMokrassar]

Here you should check that:

1. Values from old map (before changes) presented in diffs with strict (===) comparison
2. Values from old map absent in the oldMap after applyDiff (with strict check too)
3. Values in oldMap after applyDiff strictly (===) equal to the values from newMap by the same keys