Test all branches of LanguageChangedEvent

src/main/java/app/events/LanguageChangedEvent.java

@@ -17,18 +17,22 @@ public class LanguageChangedEvent extends Event {
   public LanguageChangedEvent(String language) {
     this.language = language;
 
-    switch (language) {
+    switch (language.toLowerCase()) {
 
-      case "Java":
+      case "java":
         Model.setLanguage(new Java());
         break;
 
-      case "Markdown":
+      case "markdown":
         Model.setLanguage(new Markdown());
         break;
 
-      default:
+      case "empty":
+        Model.setLanguage(new Empty());
         break;
+
+      default:
+        throw new IllegalArgumentException("Could not recognize language: " + language);
     }
   }
 

src/test/java/app/events/LanguageChangedEventTest.java

@@ -1,9 +1,12 @@
 package app.events;
 
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
 import app.model.Model;
+import app.model.languages.Empty;
 import app.model.languages.Java;
 import app.testing.EventTestTemplate;
 
@@ -16,4 +19,20 @@ public class LanguageChangedEventTest extends EventTestTemplate {
       this.mockModel.verify(() -> Model.setLanguage(new Java()));
   }
 
+
+  @Test
+  @DisplayName("Change into every possible language")
+  private void checkPossibleLanguages() {
+      new LanguageChangedEvent("Java");
+      this.mockModel.verify(() -> Model.setLanguage(new Java()));
+
+      new LanguageChangedEvent("Markdown");
+      this.mockModel.verify(() -> Model.setLanguage(new Java()));
+
+      new LanguageChangedEvent("Empty");
+      this.mockModel.verify(() -> Model.setLanguage(new Empty()));
+
+      assertThrows(IllegalArgumentException.class, () -> new LanguageChangedEvent("")); 
+  }
+    
 }