Flight-like Flight Software Testing Methods Celina A Garcia Jet Propulsion Laboratory California Institute of Technology ©2009 California Institute of

Flight-like Flight Software Testing Methods

Celina A Garcia

Jet Propulsion LaboratoryCalifornia Institute of Technology

©2009 California Institute of Technology. Government sponsorship acknowledged.

Introduction

Flight Software (FSW) testing methods used by Mars Science Laboratory (MSL)– Not a new concept, many contributors

What is “flight-like” testing?– Same means & methods used in Mission

Operations– Use flight scenarios similar to those

defined by Systems to test FSW

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Previous FSW Test Methods

Past experience with FSW test methods– FSW Developer: white box testing– FSW Build & Integration: minimal gray box

testing– Systems Engineering: black box testing

Normal S/W development, the schedule can absorb any changes due to design flaws

Tight S/W schedules can’t afford to catch design flaws during Systems Eng. & ATLO (Assembly Test & Launch Ops) testing.


Issue

FSW schedule is impacted– Very tight schedule– Unscheduled point releases due to

problems found during systems tests Causes:

– FSW team testing did not necessarily include sending commands and verifying telemetry

– Dynamic design and/or poor interpretation of requirements & functionality


Solution

Formation of MSL FSW internal test (FIT) team– Objective: Use gray box testing approach to

discover FSW problems before Systems Eng. testing does

– Employ same interfaces to S/C as Systems Eng.

– Use FSW knowledge to test & stress FSW in ways Systems Eng. may not• FSW Event Reporting throttling• Stressing uplink & downlink

Results in fewer point builds & ensures a more stable FSW product


FIT Approach

Gray box testing– “Test as you fly and fly as you test”– Mix of black & white box testing– Going beyond traditional unit testing– Testing against FSW requirements &

functionality described in Functional Description Documents

– Ensure that FSW works how Systems Eng. expects it to work

– Make use of Ground S/W tools• scripting interface

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FIT Approach (cont.)

– Test using same venues as Systems Eng.• Workstation Testset (WSTS)

– simulated avionics with closed loop simulation for Attitude Control Sys. & Entry, Descent, & Landing

• Testbed– combination of simulated and real avionics with

closed loop simulation as well

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Flight-like FSW Testing Process

FIT testers create functional tests by:– Reviewing Functional Description

Documents (FDDs) and FSW design docs– Consulting FSW developer and Systems

Engineer– Test script design & test results are

reviewed & approved– Testing done using Workstation Simulation

Testset and/or Testbed


Initial Results

In progress Short term benefits:

– FSW integration is an easier task near code freeze and release

– FSW has access to the FIT test suite– FIT can act as a liaison between Systems,

Ground S/W and FSW developer– Provide early feedback to Ground &

Simulation S/W– Functional tests become means for

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Contact Info

E-mail: [email protected] MSL FSW Build & Integration Lead &

FIT team member
