# 1. Goal
A company groups its departments in a hierarchy. Each department can have a
parent department. A report and an OData service read the departments and also
need the data of the parent department. The data must come from the database,
from a CDS view entity. An ABAP SQL consumer reads the parent data with a path
expression.

# 2. Open questions
None.

# 3. Context
- Table {{P}}DEPT (department), package $TMP. Key: DEPT_ID (CHAR 8).
  Fields: DEPT_NAME (CHAR 30), PARENT_ID (CHAR 8), HEADCOUNT (INT4).
- PARENT_ID holds the DEPT_ID of the parent department. The top department has
  an empty PARENT_ID. A PARENT_ID can also point to a department that does not
  exist.

# 4. Contract
- Create the CDS view entity {{P}}I_DEPT in package $TMP.
- Elements, with these names: DEPT_ID (key), DEPT_NAME, PARENT_ID, HEADCOUNT.
- The view has an association with the name _PARENT. The association points to
  the department data. Through the association, a consumer can read the
  DEPT_NAME and the other elements of the parent department.
- No authorization check (#NOT_REQUIRED).

# 5. Business rules
1. The view shows one row for each department in {{P}}DEPT.
2. DEPT_ID is the key element of the view.
3. The association _PARENT matches the department whose DEPT_ID is the PARENT_ID
   of the current department. A department has at most one parent department.
4. A department with an empty PARENT_ID has no parent department. Reading the
   parent's DEPT_NAME through the association gives an empty value.
5. A department whose PARENT_ID does not match any department has no parent
   department. Reading the parent's DEPT_NAME through the association gives an
   empty value.
6. DEPT_NAME, PARENT_ID and HEADCOUNT show the values of the department itself.

# 6. Constraints
- Release target: 8.16.
- Coding standards: Clean ABAP.
- Out of scope: do not change {{P}}DEPT and {{P}}SEED_DEPT.

# 7. Acceptance
- The view is active and has no syntax error.
- The hidden tests pass.
- Write ABAP Unit tests with CL_CDS_TEST_ENVIRONMENT in a global test class.