 <p>You will need to do the printing yourself, as everyone suggested here.</p> <p>It's worthy to note that some languages (e.g. Scala, Ruby, Groovy) have language features that enable you to write:</p> <pre><code>x should be(3) </code></pre> <p>And that will report:</p> <pre><code>0 should be 3 but is not. </code></pre> <p>In Groovy, with <a href="http://code.google.com/p/spock" rel="nofollow noreferrer">Spock testing framework</a>, you can write:</p> <pre><code>def "my test": when: x = 0 expect: x == 3 </code></pre> <p>And that would output:</p> <p>Condition not satisfied:</p> <pre><code>x == 3 | | | 0 | 3 false </code></pre> <p>I don't think this possibly cleanly in python though.</p>