unit testing with tessy

Automated dynamic Unit and Integration Testing

TESSY automates unit testing for embedded C/C++ software, guiding users through the entire testing workflow while managing test organization and providing comprehensive reporting.

Unit testing with TESSY

Unit testing with TESSY

TESSY performs automated dynamic module / unit and integration testing of embedded software in C/C++ and determines the code coverage along the way. This kind of test is required for certifications according to standards such as DO-178, IEC 61508, or ISO 26262.

Basic functionality of TESSY

Principle of unit testing with TESSY

For programs written in the C programming language, a unit or a module is a function in the sense of C; for programs in C++, a unit or a module is a method. To start unit testing with TESSY, you simply browse for the source module containing the unit to be tested.

TESSY automatically determines the interface of the unit under test. The interface essentially consists of the set of input variables and the set of output variables of this unit. TESSY automatically generates the software for a test driver that allows the unit under test to be called in isolation from the rest of the application. The user supplies the test input data to the unit under test and the expected results.

Units called by the unit under test can be replaced by stubs (also known as mocks) with a defined behavior. Such stubs can check whether they were called with valid parameters and can return predefined values with which the unit under test shall work. These stubs are created by TESSY completely. Test drivers and the unit under test are compiled and linked by TESSY, usually with the cross compiler for the embedded system in question. The tests are carried out by TESSY directly on the embedded system, but can also run on the host. Actual test results are automatically compared to expected results and test reports are generated.

TESSY Frequently Asked Questions


We have put together the most frequently asked questions on TESSY and module/unit testing. The FAQs are categorized starting from general questions and moving on to more technical questions.

Frequently asked questions
Get your TESSY evaluation version

Free-of-charge, full-featured evaluation

Get the full-featured TESSY free trial. Get to know and appreciate TESSY step by step. Here on the web or upon request from our TESSY team, you will find numerous assistance, tips and tricks for the first steps!

Free TESSY evaluation
Get to know TESSY

Get to know TESSY better

Dive deeper into the module and unit test with TESSY: take a look at our YouTube channel and watch the entire "TESSY program" - from the introduction to special functions!

TESSY videos for beginners and pros
TESSY's basic functionality

TESSY's basic functionality

TESSY lets you configure a test project that links source files to test and test result. The Test Environment Editor (TEE) allows to configure the settings of your test project, e.g. to select the embedded cross compiler and the software debugger to use. TESSY determines the interface of the test object and lets you specify the test cases.

Discover basic functionality
Component / integration testing

Component / integration testing

Component testing is integration testing of the units. A component according to this specification may also be called a “module”, and its testing “module testing” respectively.

Component / Integration Testing
TESSY's requirement management system

Requirement management

One can create requirements in TESSY or import requirements from files in various formats, e.g. ReqIF. Requirements can be linked to test cases in TESSY. Reports reveal, if all requirements are tested. Requirements can also be exported together with the information about the test cases linked to a requirement.

Requirement Management
TESSY can generate test cases

Test case creation

Besides the interactive manual creation of test cases, TESSY can generate test cases from value ranges and can import test cases from files (e.g. Excel, scripts). TESSY also includes the Classification Tree Editor (CTE) for test case specification according to the Classification Tree Method (CTM).

Test case creation with the CTE
helpful and informative documents for the use for TESSY

TESSY documents

We have made a large collection of helpful and informative documents available for you to download and use for TESSY and the unit/module test.

TESSY download area
Contact us with your TESSY questions!

TESSY contact

Do you have any questions about TESSY that we couldn't answer here? Would you like to arrange a web session about TESSY with us or do you need further advice? Contact us!

Contact us!

Unit Test Training

Format: online training
Duration: 5 days, from 8:30 a.m. to 1 p.m.
Language of instruction: English
Cost: 1,980.00 EUR (early bird discount 100 EUR)


Vom 17. bis 21. Juni 2024 findet ein Unit-Test Online-Training auf Deutsch statt.