Improve test coverage for test 6.1.18

[peinjoh]

Test 6.1.18 states:

It MUST be tested that no item of the revision history has a number of 0 or 0.y.z when the document status is final or interim.

During the implementation of 6.1.18 in csaf-rs/csaf, we identified that the current coverage does not fully cover the functionality of the test.

Currently, there is one test for CSAF 2.0 and 2.1 (6-1-18-01), which checks the combination of document status final and a revision history with an item with number 0.

We propose to extend the test coverage as follows:

• One more failing test, which checks the combination of document status final or interim and a revision history with an item with number 0.y.z.
• One more passing test, which checks the combination of document status draft and a revision history with an item with number 0 or 0.y.z.

We already implemented these test cases on our site as part of our development work. The naming schema mirrors the existing tests, prefixed with "s" for "supplementary". We hope these can be helpful examples.

• S01: added failing test (document status final and revision history item number 0.9.0)

  • S01 for CSAF 2.0
  • S01 for CSAF 2.1

• S11: added passing test (document status draft and revision history item number 0.9.0)

  • S11 for CSAF 2.0
  • S11 for CSAF 2.1

This issue was announced here: https://groups.oasis-open.org/discussion/new-issue-improve-test-coverage-for-test-6118