Our organization is in the process of preparing for a CMMI Maturity Level 2 SCAMPI A appraisal. We are concerned about our approach for bi-directional traceability REQM SP 1.4. We maintain traceability is follows:
1. High Level Requirements <--> Use Cases (Includes GUIs and Database Interactions) <--> Test Cases
2. Use Cases <--> Source Code
Note: One can trace from Test Cases to Source Code through the Use Cases and Vice Versa, but the traceability is not direct. The reason behind this is, test cases are generated from use cases and are tested against the application (black box testing). Source code does not have associated test cases.
Is this kind of traceability considered bi-directional and is satisfactory for Maturity Level 2?
What you describe is one of many ways to implement bi-directional traceability and meet the intent of the CMMI. If your method supports your business goals and objectives and there are no quality issues, your approach should be acceptable for a Maturity Level 2 appraisal.
It is interesting that you think tracing from Test Cases to Source Code via Use Cases may not be acceptable. Traceability is a multi-dimensional mapping that can have one-to-many and many-to-one relationships. As long as you trace from the top all the way to the bottom and vice versa, you should be fine no matter how many links there are in the chain, and the chain can have branches as well.
Please note that bi-directional traceability does not mean tracing one whole document to another whole document. What it means is that a given item in one document (a specific requirement for example) can trace to multiple items in another document, multiple items in one document can trace to one item in another document, one item can trace to one item, etc.