# 1. Goal
A personnel system stores employees. Each employee can have a manager, who is
also an employee. A report reads the manager data of the employees. The data
must be in the database, in CDS views. The report uses an association in an
ABAP SQL path expression.

# 2. Open questions
None.

# 3. Context
- Table {{P}}EMP (employee), package $TMP. Key: EMP_ID (CHAR 10).
  Fields: MANAGER_ID (CHAR 10, the EMP_ID of the manager), EMP_NAME (CHAR 40),
  DEPARTMENT (CHAR 10), IS_MANAGER (CHAR 1, 'X' for a manager).
- The table is filled by the seed class {{P}}SEED_DATA.

# 4. Contract
- Create the CDS view entity {{P}}I_MANAGER in package $TMP.
  Scalar elements: MGR_ID (key), MGR_NAME, MGR_DEPT.
- Create the CDS view entity {{P}}I_EMPLOYEE in package $TMP.
  Scalar elements: EMP_ID (key), MANAGER_ID, EMP_NAME, DEPARTMENT.
- {{P}}I_EMPLOYEE also has the exposed association _MANAGER. _MANAGER is an
  element of the view. It is not a scalar element.
- Both views have no authorization check (#NOT_REQUIRED).

# 5. Business rules
1. {{P}}I_MANAGER shows one row for each row of {{P}}EMP with IS_MANAGER = 'X'.
   MGR_ID, MGR_NAME and MGR_DEPT have the values of EMP_ID, EMP_NAME and
   DEPARTMENT of that employee.
2. {{P}}I_EMPLOYEE shows one row for each row of {{P}}EMP. EMP_ID, MANAGER_ID,
   EMP_NAME and DEPARTMENT have the values of the employee.
3. The association _MANAGER leads from an employee to the manager of the
   employee. The manager is the row of {{P}}I_MANAGER whose MGR_ID is the
   MANAGER_ID of the employee. An employee whose MANAGER_ID is empty or has no
   such row has no manager.
4. _MANAGER is part of the public interface of {{P}}I_EMPLOYEE. An ABAP SQL
   statement reads the manager data with the path expression
   {{P}}I_EMPLOYEE\_MANAGER. Example:
     SELECT FROM {{P}}I_EMPLOYEE\_MANAGER FIELDS mgr_name
       INTO TABLE @DATA(lt_name).
   The elements of the path expression are the elements of the manager, not
   the elements of the employee.

# 6. Constraints
- Release target: 8.16.
- Out of scope: do not change {{P}}EMP.
- Use ABAP SQL and CDS only.

# 7. Acceptance
- Both views are active and have no syntax error.
- The hidden tests pass.
- Write ABAP Unit tests with CL_CDS_TEST_ENVIRONMENT in a global test class.