cover & comment right border trim behavior to be fixed

src/Buffer.test.ts

@@ -489,5 +489,22 @@ describe('Buffer', () => {
       const bufferIndex = terminal.buffer.stringIndexToBufferIndex(0, stringIndex);
       assert(terminal.buffer.lines.get(bufferIndex[0]).get(bufferIndex[1])[CHAR_DATA_CHAR_INDEX], '😃');
     });
+    it('multiline fullwidth chars with offset 1 (currently tests for broken behavior)', function(): void {
+      const input = 'a１２３４５６７８９０１２３４５６７８９０';
+      // the 'a' at the beginning moves all fullwidth chars one to the right
+      // now the end of the line contains a dangling empty cell since
+      // the next fullwidth char has to wrap early
+      // the dangling last cell is wrongly added in the string
+      // --> fixable after resolving #1685
+      terminal.write(input);
+      // TODO: reenable after fix
+      // const s = terminal.buffer.contents(true).toArray()[0];
+      // assert.equal(input, s);
+      for (let i = 10; i < input.length; ++i) {
+        const bufferIndex = terminal.buffer.stringIndexToBufferIndex(0, i + 1); // TODO: remove +1 after fix
+        const j = (i - 0) << 1;
+        assert.deepEqual([(j / terminal.cols) | 0, j % terminal.cols], bufferIndex);
+      }
+    });
   });
 });

src/Buffer.ts

@@ -202,6 +202,7 @@ export class Buffer implements IBuffer {
    * The method operates on the CharData width attribute, there are no
    * additional content or boundary checks. Therefore the string and the buffer
    * should not be altered in between.
+   * TODO: respect trim flag after fixing #1685
    * @param lineIndex line index the string was retrieved from
    * @param stringIndex index within the string
    * @param startCol column offset the string was retrieved from
@@ -419,6 +420,7 @@ export class BufferStringIterator implements IBufferStringIterator {
     const range = this._buffer.getWrappedRangeForLine(this._current);
     let result = '';
     for (let i = range.first; i <= range.last; ++i) {
+      // TODO: always apply trimRight after fixing #1685 
       result += this._buffer.translateBufferLineToString(i, (this._trimRight) ? i === range.last : false);
     }
     this._current = range.last;