title: Understanding assert_equal in Test::Unit with Ruby on Rails
body: <p>I have the following code:</p>
  
  <pre><code>test "unique title" do
      product = Product.new(title:       products(:ruby).title,
                            description: 'yyy',
                            price:       1,
                            image_url:   "fred.gif")
  
      assert !product.save
      puts product.errors[:title].join('; ')
      assert_equal "has already been taken", product.errors[:title].join('; ')
    end
  </code></pre>
  
  <p>The test passes. But I fail to understand why the assert_equal doesn't trigger an error. </p>
  
  <p>Because "has already been taken" is not equal to: <code>ProductTest#test_unique_titlehas already been taken</code></p>
  
  <p>Which is the output of the puts statement.</p>
  
  <p>Why does this test pass?</p>