PHPUnit没有在assertEquals失败时显示差异

I'm using PHPUnit 3.7.10 via CakePHP v2.3 and I run the following:

$this->assertEquals(array('a', 'b', 'c'), array('a', 'c', 'd'));

And all I get is:

Failed asserting that two arrays are equal.

Why do I not get the diff below as outlined here? http://www.phpunit.de/manual/current/en/writing-tests-for-phpunit.html#writing-tests-for-phpunit.assertions.assertEquals.example5

Failed asserting that two arrays are equal.
--- Expected
+++ Actual
@@ @@
 Array (
     0 => 'a'
-    1 => 'b'
-    2 => 'c'
+    1 => 'c'
+    2 => 'd'
 )

What am I missing?

Update. Test file called via test.php?case=Cache/Engine/PhpUnit&debug=1

<?php

class PhpUnitTest extends CakeTestCase {
    public function testDiff() {
        $this->assertEquals(array('a', 'b', 'c'), array('a', 'c', 'd'));
    }
}

This was a regression bug in CakePHP 2.3. Fixed in https://github.com/cakephp/cakephp/commit/659715664d648d9a599002b5a7c3b55505efdcde

For ref here was the ticked I opened: http://cakephp.lighthouseapp.com/projects/42648/tickets/3503-23-suppresses-phpunit-diff-output

Works for me:

<?php
class SoTest extends PHPUnit_Framework_TestCase
{
    public function testIt()
    {
        $this->assertEquals(array('a', 'b', 'c'), array('a', 'c', 'd'));
    }
}
?>

Output:

$  phpunit SoTest.php 
PHPUnit 3.7.10 by Sebastian Bergmann.

F

Time: 0 seconds, Memory: 3.00Mb

There was 1 failure:

1) SoTest::testIt
Failed asserting that two arrays are equal.
--- Expected
+++ Actual
@@ @@
 Array (
     0 => 'a'
-    1 => 'b'
-    2 => 'c'
+    1 => 'c'
+    2 => 'd'
 )

/home/cweiske/SoTest.php:6

FAILURES!
Tests: 1, Assertions: 1, Failures: 1.

You are running the unit tests on the browser. You will see the expected result when you run it on the CLI with --debug modifier. You can also try adding &debug=1 at the end of the url when using the web browser to run the tests but that has not worked many times for me.