fix out of bounds bug

Author: jhchen

diff.js

@@ -641,7 +641,11 @@ function fix_cursor (diffs, cursor_pos) {
   var d = ndiffs[cursor_pointer];
   var d_next = ndiffs[cursor_pointer + 1];
 
-  if (d[0] !== DIFF_EQUAL) {
+  if (d == null) {
+    // Text was deleted from end of original string,
+    // cursor is now out of bounds in new string
+    return diffs;
+  } else if (d[0] !== DIFF_EQUAL) {
     // A modification happened at the cursor location.
     // This is the expected outcome, so we can return the original diff.
     return diffs;

test.js

@@ -38,7 +38,7 @@ for(var i = 0; i < ITERATIONS; ++i) {
 
 console.log('Running tests *with* cursor information');
 for(var i = 0; i < ITERATIONS; ++i) {
-  var cursor_pos = Math.floor(random() * strings[i].length);
+  var cursor_pos = Math.floor(random() * strings[i].length + 1);
   var diffs = diff(strings[i], strings[i+1], cursor_pos);
   var patch = googlediff.patch_make(strings[i], strings[i+1], diffs);
   var expected = googlediff.patch_apply(patch, strings[i])[0];