added unifyTest

pom.xml

@@ -54,8 +54,8 @@ http://maven.apache.org/maven-v4_0_0.xsd">
 				<version>3.8.0</version>
 				<configuration>
 					<compilerArgs>--enable-preview</compilerArgs>
-                    <source>19</source>
+                    <source>21</source>
-                    <target>19</target>
+                    <target>21</target>
                 </configuration>
 			</plugin>
 			<plugin>

src/main/java/de/dhbwstuttgart/core/JavaTXCompiler.java

@@ -88,8 +88,9 @@ public class JavaTXCompiler {
 		this(sourceFiles, null);
 	}
     public JavaTXCompiler(List<File> sources, List<File> contextPath) throws IOException, ClassNotFoundException {
-    	statistics = new FileWriter(new File(System.getProperty("user.dir") + "/" + sources.get(0).getName() + "_"+ new Timestamp(System.currentTimeMillis())));
+    	//statistics = new FileWriter(new File(System.getProperty("user.dir") + "/" + sources.get(0).getName() + "_"+ new Timestamp(System.currentTimeMillis())));
-    	statistics.write("test");
+    	statistics = new OutputStreamWriter(new NullOutputStream());
+		statistics.write("test");
         if(contextPath == null || contextPath.isEmpty()){
         	//When no contextPaths are given, the working directory is the sources root
 			contextPath = Lists.newArrayList(new File(System.getProperty("user.dir")));

src/main/java/de/dhbwstuttgart/typeinference/unify/TypeUnifyTask.java

@@ -56,6 +56,7 @@ import java.io.OutputStreamWriter;
 import java.io.Writer;
 
 import com.google.common.collect.Ordering;
+import org.apache.commons.io.output.NullWriter;
 
 
 /**
@@ -161,7 +162,10 @@ public class TypeUnifyTask extends RecursiveTask<Set<Set<UnifyPair>>>  {
 		this.statistics = statistics;
 	}
 	public TypeUnifyTask(Set<UnifyPair> eq, List<Set<Constraint<UnifyPair>>> oderConstraints, IFiniteClosure fc, boolean parallel, Writer logFile, Boolean log, int rekTiefe, UnifyResultModel urm, UnifyTaskModel usedTasks) {
-		synchronized (this) { 
+		synchronized (this) {
+            if(statistics==null){
+                statistics = new NullWriter();
+            }
 			this.eq = eq;
 			//this.oderConstraints = oderConstraints.stream().map(x -> x.stream().map(y -> new HashSet<>(y)).collect(Collectors.toSet(HashSet::new))).collect(Collectors.toList(ArrayList::new));
 			this.oderConstraintsField = oderConstraints; /*.stream().map(x -> {