1. Requirements

1.1 Notes

NPR 7150.2, NASA Software Engineering Requirements, does not include any notes for this requirement.

1.2 History

1.3 Applicability Across Classes

2. Rationale

Test results are the basis for confirming that the team has fulfilled the software requirements in the resulting software product. To make such decisions, test results must be reviewed and evaluated using a documented, repeatable process. The team can derive quality conclusions by capturing the actual test results, comparing them to expected results, analyzing those results against pre-established criteria, and documenting that analysis/evaluation process.

3. Guidance

Evaluation of software testing is a complicated activity and the evaluations are further impacted by the amount of data produced by the software test.  All software test data should be evaluated and compared to the expected results for the test.  The evaluation process and evaluation tools used should be recorded for future assessments.  If a software test evaluation tool has an error, the software test data may be misinterpreted by the evaluation team.  The process for software test evaluations should be repeatable.

The following from IEEE-STD-1012-2004, IEEE Standard for Software Verification and Validation,

• Validate that software correctly implements the design.
• Validate that the test results trace to test criteria established by the test traceability in the test planning documents.
• Validate that the software satisfies the test acceptance criteria.
• Verify that the software components are integrated correctly.
• Validate that the software satisfies the system requirements.

Other elements for the evaluation methodology include:

• Verify that the test results cover the requirements.
• Determine if actual results match expected results.
• Verify adequacy and completeness of test coverage.
• Determine the appropriateness of test standards and methods used.

For all levels of software testing (unit, component, integration, etc.) capture and record items used to generate and collect the results. These items are an important part of analyzing the test results since some anomalies could have been caused by the tests themselves. The following are captured, not only for results analysis but for future regression testing:

• Simulators.
• Test drivers and stubs.
• Test suites.
• Test data.

In addition to the information used to generate test results, the following may be important inputs to the analysis of the result:

• Discrepancies found during testing (e.g., discrepancies between expected and actual results).
• Disposition of discrepancies.
• Retest history.

When performing the actual test results analysis/evaluation, consider the following practices

• Use application or domain specialists as part of the analysis/evaluation team.
• Use checklists to assist in the analysis and ensure consistency.
• Use automated tools to perform the analysis, when possible.
• Capture a complete account of the procedures that were followed.
• If a test cannot be evaluated, capture that fact and the reasons for it.
• Plan the criteria to be used to evaluate the test results, consider (from a 1997 University of Southern California Center for System and Software Engineering project file entitled, “Software Test Description and Results”):

• The range or accuracy over which output can vary and still be acceptable.
• The minimum number of combinations or alternatives of input and output conditions constitute an acceptable test result.
• Maximum/minimum allowable test duration, in terms of time or number of events.
• The maximum number of interrupts, halts or other system breaks that may occur.
• Allowable severity of processing errors.
• Conditions under which the result is inconclusive and retesting is to be performed.
• Conditions under which the outputs are to be interpreted as indicating irregularities in input test data, in the test database/data files, or test procedures.
• Allowable indications of the control, status, and results of the test and the readiness for the next test case (maybe the output of auxiliary test software).
• Additional criteria not mentioned above.

When recording the outcome of the analysis, important items to include are:

• Major anomalies.
• Problem reports were generated as a result of the test.
• Operational difficulties (e.g, constraints or restrictions imposed by the test, aspects of the requirement under test that could not be fully verified due to test design or testbed limitations).
• Abnormal terminations.
• Reasons/justifications for discrepancies (e.g., caused by test cases or procedures, not a product issue).
• Any known requirement deficiencies present in the software element tested.
• Corrective actions were taken during testing.
• Success/failure status of the test.

Additional guidance related to software test results may be found in the following related requirements in this Handbook:

4. Small Projects

No additional guidance is available for small projects.

5. Resources

5.1 References

5.2 Tools

6. Lessons Learned

6.1 NASA Lessons Learned

A documented lesson from the NASA Lessons Learned database notes the following:

• Flight Software Reviews (Have test results peer-reviewed.) Lesson Number 1294

  Swerefn
  refnum 548

  : "Rigorous peer reviews of spacecraft bus software resulted in good on-orbit performance. A lack of rigorous peer reviews of the instrument software has resulted in numerous on-orbit patches and changes."

6.2 Other Lessons Learned

No other Lessons Learned have currently been identified for this requirement.

7. Software Assurance

7.1 Tasking for Software Assurance

1. Confirm that test results are assessed and recorded.

2. Confirm that the project documents software non-conformances in a tracking system.

3. Confirm that test results are sufficient verification artifacts for the hazard reports.

7.2 Software Assurance Products

• SA assessment of verification adequacy for hazard reports.

  
  

  Note
  title Objective Evidence
  Software test report(s) Software problem report or defect data. Software test coverage metric data.

  Expand
  title Definition of objective evidence
  Include Page SITE:Definition of Objective Evidence SITE:Definition of Objective Evidence

7.3 Metrics

• # of software work product Non-Conformances identified by life-cycle phase over time
• # of safety-related Non-Conformances
• Total # of Non-Conformances over time (Open, Closed, # of days Open, and Severity of Open)
• # of Non-Conformances in the current reporting period (Open, Closed, Severity)
• # of safety-critical requirement verifications vs. total # of safety-critical requirement verifications completed
• # of Open issues vs. # of Closed over time
• # of tests successfully completed vs. total # of tests
• # of Hazards containing software that has been successfully tested vs. total # of Hazards containing software
• # of Non-Conformances identified during each testing phase (Open, Closed, Severity)
• # of tests executed vs. # of tests successfully completed
• # of Non-Conformances identified while confirming hazard controls are verified through test plans/procedures/cases
• # of hazards with completed test procedures/cases vs. total number of hazards over time
• # of safety-related non-conformances identified by life-cycle phase over time
• # of Safety-Critical tests executed vs. # of Safety-Critical tests witnessed by SA
• Total # of tests completed vs. number of test results evaluated and signed off

7.4 Guidance

Software assurance needs to review all software test reports and assess whether the results of the test(s) have been accurately captured. Software assurance will confirm that any discrepancies /nonconformances found during the test(s) are fully described in the test report and documented in the project tracking system. The discrepancies/nonconformances need to be addressed and resolutions agreed upon before software assurance signs off on the test completion. 

Software assurance will review the test reports and confirm that all software safety-related verifications in the Hazard Report or Safety Package have been tested and assure they are performed according to the test plan, test procedures, and or safety plan.  Testing of these features should include correct and safe operations in known operational and nominal configurations as well as the ability to handle off-nominal conditions and transition to a safe state. Testing should also include testing of the software under load, stress, and off-nominal conditions including the operation of software controls and mitigations in various modes and states. Any discrepancies or nonconformances should be documented and addressed before the closure of the hazard verification.