[SUREFIRE-2071] failIfNoTests config option to fail when no tests are found (in a given module)

**[Marcin Zajaczkowski](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=szpak)** opened **[SUREFIRE-2071](https://issues.apache.org/jira/browse/SUREFIRE-2071?redirect=false)** and commented

TL;TR. When enabled, failIfNoTests set to "true" in the Surefire (also Failsafe?) configuration should fail its execution when no tests found in a given module.

Rationale. Recently, adding SonarQube reporting in a multi module Maven project (which I didn't know well), I was surprised that the XML reports (from JUnit 5) on CI are generated only for one module. After some investigation, I've noticed that due to migration to JUnit Platform in that one module, tests in JUnit 4 from the other modules were not executed at all (in Maven/Surefire) due to dependency misconfiguration. However, they were executed fine in Idea.

With that flag (hopefully enabled by default in Surefire 3.0-final), people making a migration would be alarmed about the problem - 0 tests in some module. Without that, the problem could be hidden for some time (if developers run them from IDE).

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**Affects:** 3.0.0-M6

Start by reading the requested failIfNoTests behavior for Surefire and the possible Failsafe counterpart, then inspect how test execution is configured across Maven modules. Clarify whether the option should be enabled by default and what counts as no tests, including JUnit 4 and JUnit 5 migration cases. Done means a module with no discovered tests fails when enabled, with the behavior covered for the relevant plugin configuration.

Written by the indexing model from the issue text.