SelectionState `hasEdgeWithin` has a false positive case

[andrewbranch]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?

Terminology: “target range” is the range described by the arguments to hasEdgeWithin.

When a SelectionState is confined to a single block, hasEdgeWithin returns true when one edge is before the target range and the other edge is after the target range. (I.e., a special case of neither edge being within the target range.)

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem.

https://runkit.com/andrewbranch/5aac76e3315c160012a07b84

const selection = SelectionState.createEmpty('a').merge({
  anchorOffset: 0,
  focusOffset: 20
});

// currently returns true, even though neither 0 nor 20 is between 5 and 10
selection.hasEdgeWithin('a', 5, 10);

What is the expected behavior?

hasEdgeWithin returns false for all cases where neither selection edge is within the target range.

Which versions of Draft.js, and which browser / OS are affected by this issue? Did this work in previous versions of Draft.js?

The hasEdgeWithin algorithm hasn’t changed since Draft JS was open sourced.

[andrewbranch]

The method has test coverage, but seems not to test this case if I’m following it correctly.

If you can confirm that this is indeed a bug, and my expected behavior is correct, I can contribute a failing test and a fix. Thanks!