I have seen the following question and the answer on 'Oracle Assumption' for ISTQB Foundation Level exam (Source).

19 The oracle assumption:

  • a) is that there is some existing system against which test output may be checked.
  • b) is that the tester can routinely identify the correct outcome of a test.
  • c) is that the tester knows everything about the software under test.
  • d) is that the tests are reviewed by experienced testers.

According to the site, the answer is

- b) is that the tester can routinely identify the correct outcome of a test.

However, the ISTQB glossary says that a Test Oracle is :

A source to determine expected results to compare with the actual result of the software under test. An oracle may be the existing system (for a benchmark), other software, a user manual, or an individual's specialized knowledge, but should not be the code.

Another source says that the Oracle Assumption is :

the assumption that testers will (a) work out expected ourcomes in advance of test execution, as part of test case specification; and (b) avoid doing so by hand wherever possible.

I could not find any other exact definition for Oracle Assumption online.

I have two questions :

  1. Is the answer given to the MCQ is correct/incorrect? Why?
  2. What is the correct definition of Oracle Assumption for ISTQB - Foundation Level?
  • I also don't understand how the tester knows what will be the expected outcome of a test untill it is not executed. Commented Sep 26, 2017 at 13:06

1 Answer 1


In the sample question you posted, answer (b) is correct. The Oracle Assumption is that the tester knows what the expected outcome of a test is based on other information about the system at their disposal. If the question instead read "A Test Oracle:", then the correct answer would have been (a) per the definition you cited from the ISTQB glossary. A Test Oracle is the entity that gives a tester the Oracle Assumption.

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