Test Oracle is a fundamental concept in software testing that acts as a benchmark or standard to judge whether a test case produces the expected outcome or not. It’s like a reference point against which the actual output of the software being tested is compared to determine if the test case succeeded or failed. Essentially, the test oracle helps evaluate the accuracy and quality of the software under examination.
The term “oracle” draws inspiration from the notion of an all-knowing or infallible source of truth, akin to the oracles in Greek mythology. In software testing, a test oracle serves as a dependable way to gauge whether the software behaves as anticipated and desired.
There exist various types of test oracles, each serving different purposes:
Human Oracle: This could be a human tester or an expert in the field who relies on their knowledge of the application’s requirements and expected behavior to assess test results.
Specification-Based Oracle: These oracles derive expectations from formal specifications, requirements documents, or other written sources outlining the software’s intended functionality.
Historical Data Oracle: Using past validated data as a reference point, this oracle compares the software’s current output against known correct outputs.
Automated Oracle: Scripts, algorithms, or predefined rules form automated oracles, frequently employed in regression testing and automated testing frameworks.
Model-Based Oracle: This type of oracle utilizes a model of the system’s behavior to predict outcomes and compare them with the actual results.
The selection of a suitable test oracle depends on factors such as the software’s complexity, testing objectives, and available resources.