Classic and new ABAP Debugger — Guided debugger and evidence walkthrough

Training simulation: All sample identifiers, logs, requests, transactions, values and cases are fictional. Tools and permissions vary by SAP release; perform any changes only in approved DEV/QA environments.

Classic and new ABAP Debugger — Guided debugger and evidence walkthrough

Outcome: Set the correct breakpoint, step across calls and inspect the actual changing variable.

Before you begin: Classic SAP GUI debugger and New ABAP Debugger; availability/options depend on installed SAP_BASIS release. Use only fictional test keys and an authorized development/test tenant.

Reproduce with the sample evidence

DATA(lv_amount) = CONV decfloat34( '1250.00' ).CALL METHOD zcl_discount_demo=>apply  CHANGING cv_amount = lv_amount." Observed after call: LV_AMOUNT = 0.00" Expected for customer group B: LV_AMOUNT = 1187.50 

Six-stage diagnosis

1. Set a session breakpoint before the method call in a permitted DEV report; run with a fictional customer group B.
2. Inspect LV_AMOUNT and confirm 1250.00 before the call. Capture the executing program and call stack.
3. Use F5 to enter APPLY; inspect importing and changing parameters and any field-symbol references.
4. Use F6 over routine subcalls and compare the amount after each step; isolate the statement that changes it.
5. Check the IF/CASE predicate, current customizing or condition input that selects the branch.
6. Step out, execute the complete transaction and verify amount, persisted status and a negative test in a new run.

What should be observed

1. Before APPLY, the changing parameter is 1250.00: the wrong value is introduced later.
2. Inside APPLY the active branch clears the amount: inspect predicate and input, not the ALV display.
3. After changing the DEV rule, the amount is 1187.50 and persisted display agrees.

Alternative hypotheses to rule out

• A method branch cleared the amount on an unexpected customer group.
• A field symbol or reference changed the same memory location after the expected calculation.
• The calculation was correct but a subsequent display conversion or currency formatting lost decimals.

Verify, not just fix

• Positive test: Known group B applies the documented 5% discount and produces 1187.50 for test input 1250.00.
• Negative test: Unknown groups follow an explicit documented fallback without corrupting the original amount.
• Cross-process regression: Display currency formatting and the value read back from the saved document agree with the calculation.

Test your diagnosis

Question: After F5 the highlighted statement is CLEAR lv_amount. What is the safest next step?

A. Change LV_AMOUNT in production to the expected price.
B. Inspect branch inputs, then execute one statement and compare the value.
C. Resume with F8 and claim that CLEAR caused the problem without checking.

Correct: B. Evidence must connect statement execution and branch inputs before a correction.

Production-safe approach: Never skip authorization logic or alter productive financial amounts using debugger variable editing. Use synthetic inputs and approved DEV changes.

Synthetic support case: A calculation or field value changes unexpectedly in a SAP GUI transaction.

The fictional method's fallback branch clears the amount because the group lookup does not match the intended customer category. The watchpoint/call stack identifies the actual writer.

• Debugger launch is not equivalent to proving the program is correct.
• Step Into may enter framework or generated code; Step Over is often more useful to keep context.
• Field-symbol assignment refers to underlying storage; changing a referenced row can change the original table.

Correct the exact group predicate and add ABAP Unit tests for configured and missing customer groups; avoid overriding the debugger value to hide the branch.

• Positive test: Known group B applies the documented 5% discount and produces 1187.50 for test input 1250.00.
• Negative test: Unknown groups follow an explicit documented fallback without corrupting the original amount.
• Cross-process regression: Display currency formatting and the value read back from the saved document agree with the calculation.

Never skip authorization logic or alter productive financial amounts using debugger variable editing. Use synthetic inputs and approved DEV changes.

Show practical debugger fluency: starting with /h, stepping with F5/F6/F7/F8, using breakpoints and watchpoints, inspecting variables and internal tables, and — importantly — debugging safely without changing data in production.