IDENTIFICATION DIVISION.
      *> PROGRAM-ID: RerunTest
      *> Cross-cutting: RERUN/RESTART idempotency
      *> Tests: RR-N001 through RR-N004
       PROGRAM-ID. RerunTest.
       ENVIRONMENT DIVISION.
       INPUT-OUTPUT SECTION.
       FILE-CONTROL.
           SELECT INPUT-FILE ASSIGN TO "input.dat"
               ORGANIZATION IS SEQUENTIAL
               ACCESS MODE IS SEQUENTIAL
               FILE STATUS IS FS-INPUT.
           SELECT OUTPUT-FILE ASSIGN TO "output.dat"
               ORGANIZATION IS SEQUENTIAL
               ACCESS MODE IS SEQUENTIAL
               FILE STATUS IS FS-OUTPUT.
       DATA DIVISION.
       FILE SECTION.
       FD INPUT-FILE.
       01 IN-REC.
          05 IN-KEY            PIC X(04).
          05 IN-VALUE          PIC 9(03).
       FD OUTPUT-FILE.
       01 OUT-REC.
          05 OUT-KEY           PIC X(04).
          05 OUT-VALUE         PIC 9(06).
       WORKING-STORAGE SECTION.
       77 FS-INPUT             PIC XX.
       77 FS-OUTPUT            PIC XX.
       77 WS-SUM               PIC 9(06).
       77 WS-COUNT             PIC 9(03).
       77 TC                   PIC 99 VALUE 0.
       PROCEDURE DIVISION.
      *
      * RR-N001: Initial run - create input and output
      *
       RR-N001.
           ADD 1 TO TC.
           DISPLAY "RR-N001: Create initial input data".
           OPEN OUTPUT INPUT-FILE.
           IF FS-INPUT NOT = "00"
               DISPLAY "FAIL: CREATE INPUT FS=" FS-INPUT
               STOP RUN.
           MOVE "R001" TO IN-KEY.
           MOVE 100 TO IN-VALUE.
           WRITE IN-REC.
           MOVE "R002" TO IN-KEY.
           MOVE 200 TO IN-VALUE.
           WRITE IN-REC.
           MOVE "R003" TO IN-KEY.
           MOVE 300 TO IN-VALUE.
           WRITE IN-REC.
           MOVE "R004" TO IN-KEY.
           MOVE 400 TO IN-VALUE.
           WRITE IN-REC.
           MOVE "R005" TO IN-KEY.
           MOVE 500 TO IN-VALUE.
           WRITE IN-REC.
           CLOSE INPUT-FILE.
           DISPLAY "RR-N001: PASS".
      *
      * RR-N002: Process input to output (idempotent operation)
      *
       RR-N002.
           ADD 1 TO TC.
           DISPLAY "RR-N002: Process input -> output".
           OPEN INPUT INPUT-FILE.
           IF FS-INPUT NOT = "00"
               DISPLAY "FAIL: OPEN INPUT FS=" FS-INPUT
               STOP RUN.
           OPEN OUTPUT OUTPUT-FILE.
           IF FS-OUTPUT NOT = "00"
               DISPLAY "FAIL: OPEN OUTPUT FS=" FS-OUTPUT
               STOP RUN.
           MOVE 0 TO WS-SUM.
           MOVE 0 TO WS-COUNT.
           PERFORM UNTIL FS-INPUT NOT = "00"
               READ INPUT-FILE
               AT END
                   EXIT PERFORM
               NOT AT END
                   ADD 1 TO WS-COUNT
                   MULTIPLY IN-VALUE BY 2 GIVING OUT-VALUE
                   MOVE IN-KEY TO OUT-KEY
                   WRITE OUT-REC
                   ADD IN-VALUE TO WS-SUM
               END-READ
           END-PERFORM.
           CLOSE INPUT-FILE.
           CLOSE OUTPUT-FILE.
           DISPLAY "  RECORDS=" WS-COUNT " SUM=" WS-SUM.
           IF WS-COUNT = 5 AND WS-SUM = 1500
               DISPLAY "  PROCESS OK"
           ELSE
               DISPLAY "  PROCESS FAIL"
           END-IF.
           DISPLAY "RR-N002: PASS".
      *
      * RR-N003: Re-run idempotent - same input, same result
      *
       RR-N003.
           ADD 1 TO TC.
           DISPLAY "RR-N003: Re-run idempotent verification".
           OPEN INPUT INPUT-FILE.
           MOVE 0 TO WS-SUM.
           MOVE 0 TO WS-COUNT.
           PERFORM UNTIL FS-INPUT NOT = "00"
               READ INPUT-FILE
               AT END
                   EXIT PERFORM
               NOT AT END
                   ADD 1 TO WS-COUNT
                   ADD IN-VALUE TO WS-SUM
               END-READ
           END-PERFORM.
           CLOSE INPUT-FILE.
           IF WS-COUNT = 5 AND WS-SUM = 1500
               DISPLAY "  IDEMPOTENT READ OK (same count=" WS-COUNT
                       " sum=" WS-SUM ")"
           ELSE
               DISPLAY "  IDEMPOTENT READ FAIL count=" WS-COUNT
                       " sum=" WS-SUM
           END-IF.
           DISPLAY "RR-N003: PASS".
      *
      * RR-N004: Output file already exists (STATUS 95 emulation)
      *
       RR-N004.
           ADD 1 TO TC.
           DISPLAY "RR-N004: Output file already exists".
           OPEN EXTEND OUTPUT-FILE.
           IF FS-OUTPUT = "00"
               DISPLAY "  EXTEND OPEN OK (file exists, FS=" FS-OUTPUT ")"
           ELSE
               DISPLAY "  EXTEND FS=" FS-OUTPUT
           END-IF.
           MOVE "R999" TO OUT-KEY.
           MOVE 999999 TO OUT-VALUE.
           WRITE OUT-REC.
           IF FS-OUTPUT = "00"
               DISPLAY "  APPEND OK"
           ELSE
               DISPLAY "  APPEND FAIL FS=" FS-OUTPUT
           END-IF.
           CLOSE OUTPUT-FILE.
           DISPLAY "RR-N004: PASS".
      *
      * Summary
      *
       END-TEST.
           DISPLAY "RERUN: ALL " TC " TESTS DONE".
           STOP RUN.