TESSY vs LDRA TBrun: Embedded Unit Testing Coverage, Certification Evidence, and Audit-Readiness

TESSY vs LDRA TBrun: Coverage, Certification Evidence, and Audit-Readiness

When Indian aerospace and automotive teams need unit testing tools that satisfy DO-178C or ISO 26262 certification requirements, two names frequently appear on shortlists: Razorcat TESSY and LDRA TBrun. Both are established in the safety-critical embedded space, both provide MC/DC coverage measurement, and both have been used in certified production systems worldwide.

The differences are in workflow design, audit evidence generation, target hardware support, and how each tool fits into the broader verification toolchain. This article compares the two for teams evaluating their next unit testing investment.

Coverage Metrics

TESSY measures statement, branch, decision, MC/DC, and MCC (Multiple Condition Coverage) coverage. All metrics are computed from instrumented code compiled by the project’s actual cross-compiler. Coverage results display as colour-coded source views and export as HTML/PDF reports structured for safety case inclusion.

LDRA TBrun operates within the LDRA tool suite, which also includes TBvision (structural coverage analysis) and TBsafe (safety reporting). TBrun measures statement, branch, MC/DC, and function coverage. The LDRA tool suite’s strength is the tight integration between its static analysis (LDRA Testbed) and dynamic testing (TBrun) components, coverage data flows between tools within the LDRA environment.

Both tools satisfy the structural coverage requirements of ISO 26262 Part 6, IEC 61508 Part 3, and DO-178C. TESSY’s additional MCC metric provides supplementary evidence for complex conditionals, though it is not required by any current standard.

Target Hardware Support

TESSY supports on-target unit testing through debug probes, including SEGGER J-Link, Lauterbach TRACE32, and standard JTAG/SWD interfaces. Tests compile with the project’s cross-compiler (Arm Compiler 6, IAR, TASKING, HighTec, GCC) and execute directly on the microcontroller. This matters for safety certification because coverage data comes from the actual production target, not a simulated host environment.

LDRA TBrun supports both host-based and target-based test execution. Target execution is available through LDRA’s target deployment package, which supports multiple debug interfaces. The LDRA suite has long-standing support for aerospace-grade targets (PowerPC, LEON, Arm Cortex-R) commonly used in DO-178C projects.

For Indian teams working on Infineon AURIX TC3xx (automotive ECUs in Pune and Bengaluru) or Arm Cortex-M7 (industrial controllers in Hyderabad), both tools provide adequate target support. TESSY’s integration with SEGGER J-Link is particularly streamlined, a single configuration step connects the probe, and test execution on hardware is as simple as host execution.

Certification Evidence and Audit-Readiness

This is where workflow differences matter most.

TESSY generates certification-ready reports that include: test case specifications with input/output values, expected vs actual results, coverage measurements with source annotation, and requirements traceability matrices (via ReqIF import/export). The Classification Tree Editor (CTE) provides documented test design rationale, assessors can see why each test case was created, not just what it covers. This systematic test design evidence speaks to the test case derivation routes ISO 26262 Part 6 recommends.

LDRA TBrun generates test reports within the LDRA tool suite’s reporting framework. TBsafe provides safety-focused report generation for DO-178C and ISO 26262, including coverage matrices and traceability tables. LDRA’s advantage is the unified reporting across static analysis, coding standards compliance, and dynamic testing, a single report package covers multiple verification activities.

For DO-178C DAL A projects, common in Bengaluru’s aerospace corridor, LDRA’s integrated static + dynamic reporting can simplify the certification package by presenting all verification evidence in one format. For ISO 26262 automotive projects where the static analysis tool may be different (e.g., Perforce QAC for MISRA), TESSY’s standalone dynamic testing reports integrate cleanly with reports from any static analysis tool.

Test Case Design

TESSY’s Classification Tree Editor is a graphical method for systematic test case design. Engineers define input equivalence classes, boundary values, and invalid ranges visually, then combine them in a combination table. The CTE produces an explicit design rationale that auditors can review independently of the test results.

LDRA TBrun supports manual test case creation through its test editor and provides automated test generation for coverage ramp-up. Test design documentation is generated as part of the LDRA suite’s reporting workflow.

For teams where assessment is a frequent activity (automotive OEMs with annual safety audits, aerospace programs with DER reviews), TESSY’s CTE provides stronger standalone evidence of systematic test design.

CI/CD Integration

Both tools support CI/CD pipeline integration. TESSY provides command-line batch execution for Jenkins, GitLab CI, and Azure DevOps. LDRA provides similar capabilities through its command-line interface, with the LDRA tool suite supporting automated analysis pipelines.

TESSY’s CI integration is self-contained, a single command-line invocation runs tests, measures coverage, and generates reports. LDRA’s integration involves the broader tool suite, which provides more comprehensive analysis (static + dynamic + coding standards in one pipeline) but requires the full LDRA environment to be installed on CI runners.

Licensing Model

LDRA’s tool suite is modular, TBrun (dynamic testing), Testbed (static analysis), TBvision (coverage), and TBsafe (safety reporting) are separate licensed components. The total cost for a complete safety verification workflow includes multiple modules.

TESSY provides unit testing, coverage measurement, Classification Tree design, and report generation in a consolidated package. For teams that already have a separate MISRA static analysis tool, TESSY’s focused licensing avoids paying for overlapping static analysis capabilities.

Why Buy from GSAS

GSAS Micro Systems is the authorized Razorcat partner, providing TESSY licensing with INR invoicing, proof-of-concept support, onboarding workshops, and CI/CD integration consulting. Our engineers in Bengaluru, Hyderabad, Chennai, Pune, Mumbai, and Delhi NCR work with automotive, aerospace, and industrial safety teams to evaluate TESSY against their specific toolchain, target hardware, and certification requirements. Whether your project targets ISO 26262 ASIL D for an automotive ECU or DO-178C DAL A for an avionics LRU, GSAS provides the tooling expertise and local support to make your unit testing infrastructure audit-ready.

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