Tune behavior of ignore whitespace on current line

[t9md]

Requirements

Fix #76

Description of the Change

Previously ignoreWhitespaceOnCurrentLine was not appropriately respected when one buffer is opened in multiple editors.
This PR improve behavior of ignoreWhitespaceOnCurrentLine how most user expect(I believe so).

In case test case's intention was not clear, see following illustration what happens on save.

Condition

When two editor open same file. Two editor shares same buffer.

• | represent cursor
• _ represent trailing white spaces
• editor1 have cursor at 1st line
• editor2 have cursor at 2nd line

+-------------------------+-------------------------+
| editor1                 | editor2                 |
+-------------------------+-------------------------+
| line1____|              | line1____               |
| line2____               | line2____|              |
| line3                   | line3                   |
|                         |                         |
+-------------------------+-------------------------+

case 1: saved when editor1 is active

result: editor1's cursor line was excluded

+-------------------------+-------------------------+
| editor1(active)         | editor2                 |
+-------------------------+-------------------------+
| line1____|              | line1____               |
| line2                   | line2|                  |
| line3                   | line3                   |
|                         |                         |
+-------------------------+-------------------------+

case 2: saved when editor2 is active

result: editor2's cursor line was excluded

+-------------------------+-------------------------+
| editor1                 | editor2(active)         |
+-------------------------+-------------------------+
| line1|                  | line1                   |
| line2____               | line2____|              |
| line3                   | line3                   |
|                         |                         |
+-------------------------+-------------------------+

case 3: saved when either editor1 nor editor2 was active

This situation happens when Window: Save All command was fired.

result: just removed all trailing spaces

+-------------------------+-------------------------+
| editor1                 | editor2                 |
+-------------------------+-------------------------+
| line1|                  | line1                   |
| line2                   | line2|                  |
| line3                   | line3                   |
|                         |                         |
|                         +-------------------------+
|                         | editor3(active)         |
|                         +-------------------------+
|                         | abc                     |
|                         | def                     |
+-------------------------+-------------------------+

Alternate Designs

Currently same buffer have multiple buffer.onWillSave hook.
By making this subscription per buffer basis, I think most behavior frustration described in #76 would be fixed.
But as far as I experimented it in my mind, the behavioral result would be same in that case.

So as my understanding making buffer.onWillSave subscription to per buffer-basis is kind of refactoring.
So not included in this PR.

Benefits

Users are no longer surprised by trailing WS at cursor line is removed in spite of ignoreWhitespaceOnCurrentLine is true.
This was happened when multiple same file is opened in multiple editors.

Possible Drawbacks

None

Applicable Issues

Fix #76

[ungb]

@t9md, I tried testing this fix out and I'm not seeing this working...

I added a console.log to ensure that your changes are being used.

I followed the steps in your example and looked at the issue in question. Let me know if I'm missing something.

I'm seeing the following:

[t9md]

@ungb

The behavior you showed in your GIF is expected behavior of this PR.
Which is same scenario I described as case 2: saved when editor2 is active in first comment.

When editor is saved, right pane is active, so trailing-WS at line1 is preserved, but left pane's cursor line(line2) is NOT preserved since it's not active pane when editor was saved.

I feel this behavior is natural,
You expect left inactive pane's cursor line(line2)'s trailing-WS too?

In that case, I feel it bug since

• Saving on right active pane editor does not remove tralingWS of line2 which line have no cursor on right pane editor.
• While I'm editing in right pane editor, I'm totally forgetting about cursor line of inactive pane(left pane editor).

[daviwil]

Just tested this out, looks good to me! The new tests also look good. Thanks a lot @t9md!