feat: test data and utils

assignment/src/test/java/appointmentplanner/TestUtils.java

@@ -0,0 +1,10 @@
+package appointmentplanner;
+
+import java.time.Duration;
+
+public class TestUtils {
+
+    public static Duration makeDuration(String durationString) {
+        return Duration.ofHours(Long.parseLong(durationString));
+    }
+}