title: Copy all the data from an existing database when create the test database. Django
body: <p>When I run my tests, I'd like it to copy an existing database with all the data when create the test database.</p>
  
  <p>I never thought about this till one of my colleague uses <code>POSTGIS_TEMPLATE = DATABASES['default']['NAME']</code> for his tests. 
  Because we use <code>GeoDjango</code> for our project, so <code>POSTGIS_TEMPLATE</code> exists for letting the test runner know which postgis database template to use.
  And when he define it as mentioned above, it actually creates the test database with all the data as well. It's kinda handy for us, so we don't need to create the fixture files.
  But if we can not do the same with the projects which do not use <code>GeoDjango</code>. </p>
  
  <p>So I have two questions here:
  Is it good idea to use the data already exists in the project database? (For some tests, I may need to delete all the data first for a certain table, but in many cases, we test against non empty data set.)
  If it's not a bad idea, for the project which does not use <code>GeoDjango</code>, is there anyway I can set it to copy the data from the existing database?</p>