Add tests for Factory

src/test/java/be/cylab/java/wowa/training/FactoryTest.java

+package be.cylab.java.wowa.training;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class FactoryTest {
+
+    @Test
+    void testCreateSolutionObject() {
+        Factory fact = new Factory(new SolutionDistance(5));
+        AbstractSolution solution = fact.createSolutionObject(5);
+        assertTrue(solution instanceof SolutionDistance);
+
+        Factory fact2 = new Factory(new SolutionAUC(5));
+        AbstractSolution solution2 = fact2.createSolutionObject(5);
+        assertTrue(solution2 instanceof SolutionAUC);
+
+    }
+}
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