Develop testing code snippets and testing cases to test the code developed across the tasks below. You should also develop a readme file to describe the source code and how to use it. Develop at least one good testing case for tasks below.

Develop SQL code to create a database with the contents of the separate files. The ratings.csv and tags.csv can form their own tables in the database. For movies, the genres information as they stand now are not suited for database processing since they contain genres separated by | characters. So, your task is to hold the genres information in a separate table which contains (movieId, genre) pairs. A movie with Crime and Thriller genres will generate two rows in the genres table. The remaining information from movies.csv can be exported readily into its own table.