title: How to assert that a pandas data frame filtered on a condition is true
body: <p>So I have a pytest testing the results of a query that returns pandas dataframe.</p>
  
  <p>I want to assert that a particular column <code>col</code> has all the values that are a substring of a given input.</p>
  
  <p>So this below gives me the rows (dataframe) that have that column's <code>col</code> value containing some input part. How can I assert it to be true?</p>
  
  <pre><code>assert result_df[result_df['col'].astype(str).str.contains(category)].bool == True 
  </code></pre>
  
  <p>doesn't work  </p>