'TableIterator' object has no attribute 'shape'

I am trying to get a large dataframe and pass it into a function where it cuts it into chunks.

So for testing what I have written is as below:

def test_get_dataframe(workspace):
dataframe = workspace.get_df('testing_df',True)
assert dataframe.shape[0] == 500000 

where testing_df is the large dataframe but I got this 'TableIterator' object has no attribute 'shape' error.

I am trying to use the shape method to test if there are 500k rows returned to me through chunking.

Any help?