BUGFIX Fixed tag stacking in Diff.php thirdparty lib (AIR-71)

code/Diff.php

@@ -746,7 +746,7 @@ class Diff
 						if($tagStack[$listName]) $rechunked[$listName][sizeof($rechunked[$listName])-1] .= ' ' . $item;
 						else $rechunked[$listName][] = $item;
 	
-						if($lookForTag && isset($item[0]) && $item[0] == "<" && substr($item,0,2) != "</") {
+						if($lookForTag && !$tagStack[$listName] && isset($item[0]) && $item[0] == "<" && substr($item,0,2) != "</") { 
 							$tagStack[$listName] = 1;
 						} else if($tagStack[$listName]) {
 							if(substr($item,0,2) == "</") $tagStack[$listName]--;

tests/DiffTest.php

@@ -0,0 +1,56 @@
+<?php
+/**
+ * @package cms
+ * @subpackage tests
+ */
+
+class DiffTest extends SapphireTest {
+	
+	/**
+	 * @see https://groups.google.com/forum/#!topic/silverstripe-dev/yHcluCvuszo
+	 */
+	function testTableDiff() {
+		if(!class_exists('DOMDocument')) {
+			$this->markTestSkipped('"DOMDocument" required');
+			return;
+		}
+		
+		$from = "<table> 
+		<tbody> 
+			<tr class=\"blah\"> 
+				<td colspan=\"2\">Row 1</td> 
+			</tr> 
+			<tr class=\"foo\"> 
+				<td>Row 2</td> 
+				<td>Row 2</td> 
+			</tr> 
+			<tr> 
+				<td>Row 3</td> 
+				<td>Row 3</td> 
+			</tr> 
+			</tbody> 
+		</table>";
+
+		$to = "<table class=\"new-class\"> 
+		<tbody> 
+			<tr class=\"blah\"> 
+				<td colspan=\"2\">Row 1</td> 
+			</tr> 
+			<tr class=\"foo\"> 
+				<td>Row 2</td> 
+				<td>Row 2</td> 
+			</tr> 
+		</tbody> 
+		</table>";
+		
+		$expected = "<ins>" . $to . "</ins>" . "<del>" . $from . "</del>";
+		$compare = Diff::compareHTML($from, $to);
+		
+		// Very hard to debug this way, wouldn't need to do this if PHP had an *actual* DOM parsing lib,
+		// and not just the poor excuse that is DOMDocument
+		$compare = preg_replace('/[\s\t\n\r]*/', '', $compare);
+		$expected = preg_replace('/[\s\t\n\r]*/', '', $expected);
+		
+		$this->assertEquals($compare, $expected);
+	}
+}