Software QA Testing Question:

Bottom-up testing is a technique of integration testing. A test engineer creates and uses test drivers for components that have not yet been developed, because, with bottom-up testing, low-level components are tested first. The objective of bottom-up testing is to call low-level components first, for testing purposes.
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An integration testing technique that tests the low-level components first using test drivers for those components that have not yet been developed to call the low-level components for test.