src/main/java/Job/Job.java

@@ -20,7 +20,7 @@ public abstract class Job implements HasExperience {
 
     public void levelUp() {
         level++;
-        experience = 0;
+        experience = experience - 100;
     }
 
     @Override

src/main/java/Job/Miner.java

@@ -27,4 +27,8 @@ public class Miner extends Job {
             levelUp();
         }
     }
+
+    public int remainingXpUntilLevelUp() {
+        return 100;
+    }
 }

src/test/java/MinerTest.java

@@ -6,7 +6,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 public class MinerTest {
 
     @Test
-    void miner_can_level_up() {
+    void can_level_up() {
         var job = new Miner();
         assertEquals(1, job.getLevel());
         job.levelUp();
@@ -14,20 +14,26 @@ public class MinerTest {
     }
 
     @Test
-    void miner_can_gain_xp() {
+    void can_gain_xp() {
         var job = new Miner();
         job.gainExperience(25);
         assertEquals(25, job.getExperience());
     }
 
     @Test
-    void miner_level_up_when_experience_is_100() {
+    void level_up_when_experience_cap_is_reached() {
         var job = new Miner();
-        job.gainExperience(100);
-        assertEquals(0, job.getExperience());
+        job.gainExperience(job.remainingXpUntilLevelUp());
         assertEquals(2, job.getLevel());
     }
 
+    @Test
+    void additional_xp_carries_over_on_level_up() {
+       var job = new Miner();
+       job.gainExperience(job.remainingXpUntilLevelUp() + 10);
+       assertEquals(10, job.getExperience());
+    }
+
 }