POI unit tests fail when run under non-US locale. There already is a check for this that tells what JVM flags to set to make the tests pass. However, the tests should IMHO run "out of the box", as this also might frustrate new contributors when a clean checkout and build fails for no apparent reason (the check for the locale settings is done after several tests have already failed so it's easy to overlook):

      Test testTextStrangeFormat() FAILED
      org.opentest4j.AssertionFailedError: expected: <--123456.7891> but was: <--123456,7891>
          at org.apache.poi.ss.formula.functions.TestText.testText(TestText.java:286)
    
      Test testTextEmptyStringWithDateFormat() PASSED
      Test testTextErrorAsFormat() PASSED
      Test testTextBlankTreatedAsZero() FAILED
      org.opentest4j.AssertionFailedError: expected: <0.000> but was: <0,000>
          at org.apache.poi.ss.formula.functions.TestText.testText(TestText.java:286)
    
      Test testTextErrorAsValue() PASSED
      Test testTextWithDateFormatSecondArg() PASSED
      Test testTextVariousValidNumberFormats() FAILED
      org.opentest4j.AssertionFailedError: expected: <-123456.789> but was: <-123456,789>
          at org.apache.poi.ss.formula.functions.TestText.testText(TestText.java:286)

I will prepare and commit the necessary change.