Fixed bad range usage, added test to cover

Bad range values due to copying .net code, which uses
(start, count) values, to PHP which uses (start, end) values.

Related to #4

Author: ssddanbrown

src/Diff.php

@@ -382,7 +382,7 @@ private function removeOrphans(array $matches): Generator
         $prev = new DiffMatch(0, 0, 0);
         $curr = $matches[0] ?? new DiffMatch(0, 0, 0);
 
-        foreach (array_slice($matches, 1) as $index => $next) {
+        foreach (array_slice($matches, 1) as $next) {
             // if match has no diff on the left or on the right
             if ($prev->getEndInOld() === $curr->startInOld && $prev->getEndInNew() === $curr->startInNew
                 || $curr->getEndInOld() === $next->startInOld && $curr->getEndInNew() === $next->startInNew
@@ -395,13 +395,13 @@ private function removeOrphans(array $matches): Generator
 
             $oldDistanceInChars = array_sum(array_map(function($i) {
                 return mb_strlen($this->oldWords[$i]);
-            }, range($prev->getEndInOld(), $next->startInOld - $prev->getEndInOld())));
+            }, range($prev->getEndInOld(), $next->startInOld - 1)));
             $newDistanceInChars = array_sum(array_map(function($i) {
                 return mb_strlen($this->newWords[$i]);
-            }, range($prev->getEndInNew(), $next->startInNew - $prev->getEndInNew())));
+            }, range($prev->getEndInNew(), $next->startInNew - 1)));
             $currMatchLengthInChars = array_sum(array_map(function($i) {
                 return mb_strlen($this->newWords[$i]);
-            }, range($curr->startInNew, $curr->getEndInNew() - $curr->startInNew)));
+            }, range($curr->startInNew, $curr->getEndInNew() - 1)));
             if ($currMatchLengthInChars > max($oldDistanceInChars, $newDistanceInChars) * $this->orphanMatchThreshold) {
                 yield $curr;
             }

tests/HtmlDiffTest.php

@@ -116,4 +116,10 @@ public function test_newlines_changes_between_tags_is_tracked()
         $output = Diff::excecute("<p>Section A</p><p>Section B</p>", "<p>Section A</p>\n\n<p>Section B</p>");
         $this->assertEquals("<p>Section A</p><ins class=\"diffins\">\n\n</ins><p>Section B</p>", $output);
     }
+
+    public function test_edge_changes_result_as_expected()
+    {
+        $output = Diff::excecute("AAA BBB CCC", "ZZZ BBB YYY");
+        $this->assertEquals('<del class="diffmod">AAA</del><ins class="diffmod">ZZZ</ins> BBB <del class="diffmod">CCC</del><ins class="diffmod">YYY</ins>', $output);
+    }
 }