Traditionally, the software tests are performed at different levels to achieve the DO-178B/C objectives. The Hardware-Software Integration tests (HSIT) are performed to get the High-Level Requirements coverage and Low-Level Requirement tests are performed to get the Low-Level requirements coverage and the structural coverage at the source code level. In this paper we have attempted an approach for obtaining the structural coverage from HSIT based tests and thereby eliminating/ minimizing need of low-level requirements based test.
The low-level requirements based tests are performed based on low-level requirements. The test cases are developed for each unit (or function). Each unit is tested in isolation by creating a stub functions for the external functions called by Unit under test (UUT). The stub functions are used to manipulate the control in the UUT by the return value or by the passed parameters. The structural coverage is also achieved for the UUT while performing the LLR based tests.