title: Multiline expectation RSpec testing assertion?
body: <p>How to assert the multiline string with RSpec?
  I've something like below as expectation:</p>
  
  <pre><code>it "should generate the correct header for the xml file" do
    xml_header = &lt;&lt;-XML
    &lt;?xml version="1.0" encoding="utf-8"?&gt;
    &lt;FileSpec&gt;
      &lt;Header&gt;
          &lt;Version&gt;1.0&lt;/Version&gt;
          &lt;DateTime&gt;2010-10-17T10:41:18&lt;/DateTime&gt;
          &lt;Sequence&gt;3&lt;/Sequence&gt;
          &lt;ClientID&gt;QQWW&lt;/ClientID&gt;
          &lt;FileType&gt;QQWW&lt;/FileType&gt;
      &lt;/Header&gt;
    &lt;/FileSpec&gt;
    XML
    puts SomeXml.build_xml_header
    SomeXml.build_xml_header.to_s.should == xml_header
  end
  </code></pre>
  
  <p>Though the output is as expected, the test fails due to the new-lines and tabs characters.
  How to assert in such condition? I think that <code>==</code> matcher cant handle it.</p>
  
  <pre><code>Failure/Error: SomeXml.build_xml_header.to_s.should == xml_header
   expected: "    &lt;?xml version=\"1.0\" encoding=\"utf-8\"?&gt;\n    &lt;FileSpec&gt;\n    \t&lt;Header&gt;\n    \t\t&lt;Version&gt;1.0&lt;/Version&gt;\n    \t\t&lt;DateTime&gt;2010-10-17T10:41:18&lt;/DateTime&gt;\n    \t\t&lt;Sequence&gt;3&lt;/Sequence&gt;\n    \t\t&lt;ClientID&gt;QQWW&lt;/ClientID&gt;\n    \t\t&lt;FileType&gt;QQWW&lt;/FileType&gt;\n    \t&lt;/Header&gt;\n    &lt;/FileSpec&gt;\n",
        got: "&lt;?xml version=\"1.0\" encoding=\"UTF-8\"?&gt;\n&lt;FileSpec&gt;\n  &lt;Header&gt;\n    &lt;Version&gt;1.0&lt;/Version&gt;\n    &lt;DateTime&gt;2010-10-17T10:41:18&lt;/DateTime&gt;\n    &lt;Sequence&gt;3&lt;/Sequence&gt;\n    &lt;ClientID&gt;QQWW&lt;/ClientID&gt;\n    &lt;FileType&gt;QQWW&lt;/FileType&gt;\n  &lt;/Header&gt;\n&lt;/FileSpec&gt;\n" (using ==)
  </code></pre>