Add JUnit 4 to extlib for PIT mutation testing on CI

The committed junit.jar is JUnit 3, which lacks the org.junit classes
that PIT 1.15.3 requires for test discovery. This was the root cause
of the PIT CI failure, not the TestNG warning.

Made-with: Cursor

Author: dbenn

build.xml

@@ -494,9 +494,7 @@
 	<target name="pit" depends="test">
 		<path id="mutation.path">
 			<path refid="pitest.classpath" />
-			<fileset dir="${extlib}" includes="*.jar" excludes="jacocoant.jar,testng*.jar,pitest*.jar" />
-			<pathelement location="${dist}/vstar.jar" />
-			<pathelement path="${test_build}" />
+			<path refid="test.classpath" />
 		</path>
 		<!-- export feature activated to write mutants to file -->
 		<pitest features="+EXPORT" threads="2" pitClasspath="pitest.classpath" classPath="mutation.path" targetClasses="org.aavso.tools.vstar.*" targetTests="org.aavso.tools.vstar.*" excludedtestclasses="org.aavso.tools.vstar.util.period.dcdft.*,org.aavso.tools.vstar.util.stats.DescStatsTest,org.aavso.tools.vstar.util.stats.anova.*" reportDir="${mutation_coverage_dir}" sourceDir="${src}" outputFormats="XML,HTML" />

extlib/ReadMe.txt

@@ -64,10 +64,15 @@ See the URL for the web page of each project for more information.
     * ANTLR4 http://www.antlr.org
 
 If you are a developer who wishes to contribute toward coding or 
-testing VStar, apart from JUnit 3 (junit.jar), the following libraries
-must be downloaded (e.g. from https://mvnrepository.com) for unit 
-testing purposes. Note that none of these libraries are redistributed
-as part of a VStar release.
+testing VStar, the following libraries are required for unit testing
+and CI purposes. None of these libraries are redistributed as part
+of a VStar release.
+
+  o JUnit 4 (test runner, required by pitest mutation testing)
+    - junit-4.12.jar
+    - hamcrest-core-1.3.jar
+    - Eclipse Public License 1.0 (not distributed with VStar releases)
+    - https://junit.org/junit4/
 
   o Property based testing framework
     - quicktheories-0.26.jar
@@ -91,7 +96,7 @@ under tools/spotbugs/ and used by the spotbugs Ant target. Run with:
 
 For nullness checking with the Checker Framework, the annotation
 types are in extlib and the checker processor is under tools:
-  ant checkerframework
+  ant checker
 
   o Checker Framework (3.54.1)
     - https://checkerframework.org
@@ -107,8 +112,4 @@ For mutation testing, additional libraries are required.
     - pitest-ant-1.15.3.jar
     - pitest-entry-1.15.3.jar
     - testng-7.9.0.jar
-    - JUnit 4 (or 5) required by pitest
-      o under EPL-1.0 licence: can't be linked or distributed with VStar
-        and not currently included here
-        - junit-4.12.jar
-        - hamcrest-core-1.3.jar
+    - JUnit 4 required by pitest (see above)