title: How can I create a regex that parses all lines of a string for a substring, and returns a match only if the substring is not found?
body: <p>I am trying to build a regular expression but am finding it difficult to do so for this one particular case. I want to return a match only if the string I am trying to parse does not contain a specific substring. For example (searching for the substring "test" with case insensitivity):</p>
  
  <pre><code>"Line one
  Line two
  Line test three" - Return false.
  
  "Line test one" - Return false.
  
  "Tfest" - Return true.
  
  "Tfest
  Tdhf
  Line three" - Return true.
  </code></pre>
  
  <p>I've been able to do this for single line strings using <code>^((?!message 1).)*$</code> but I'm not sure about multi-line strings.</p>
  
  <p>PS: I don't want to start a debate on using string operations VS regular expressions. Performance is a concern. The constraint of the question is that the solution must use regular expressions.</p>