ETL Testing coverage

i'm working on a testing project for ETL ,and i need to be sure that my test cases covered most of the issues in the project.Is there anyway to check this.

You have a source to target mapping specification? If yes, test that.

thanks for your replay ,
i'm a little confused about the cases when the column in the destination table come from complex query (multiple joins between tables) from the source DB .i.e in the case that employee name is stored in the contact table that have foreign key with the employee table so what will be the situation in the mapping document ?? (the Employee name in the Employee Dim cann't be mapped to the contact Name in the Contact table in the source DB)

Here are some of the test cases:

1) Test data is loaded correctly and it is conformed to the specification.
2) If data is coming from different DB, then unload source data into a file and also unload target data ( from data warehouse or ODS) into a file. Open those files into MS Access and do the data comparison and validation.
3) There should be unique index on the business keys in data warehouse or in ODS. Any data load reject should be researched or tested based on the unique business key..
4) If source data does not have all the test scenarios to test ETL process, then use existing data and updated it as per the test scenario. For example is client name must not be null and you want to test it then updated a record and make a client name null and load that data to test ETL.