title: The length of the train and test sets are different from the length of the actual set
body: <p>I'm using <code>test_forecast</code> and I have my code setup like this</p>
  <pre><code>df_train &lt;- df[1:20] 
  df_test &lt;- df[21:nrow(df)] 
  
  test_forecast(actual = df, 
                forecast.obj = forecast,
                train = df_train, 
                test = df_test)
  </code></pre>
  <p>Every row in the df is accounted for in df train and df test.</p>
  <p>But, it gives me this error</p>
  <pre><code>Error in test_forecast(actual = df, forecast.obj = forecast,  : 
    The length of the train and test sets are different from the length of the actual set
  </code></pre>
  <p><code>df</code> is a data table, but I also tried this converting all the objects to data frames and that didn't work</p>