Update karl's languages to use test runner v3 features

exercises/concept/karls-languages/build.gradle

@@ -1,23 +1,22 @@
-apply plugin: "java"
-apply plugin: "eclipse"
-apply plugin: "idea"
-
-// set default encoding to UTF-8
-compileJava.options.encoding = "UTF-8"
-compileTestJava.options.encoding = "UTF-8"
+plugins {
+  id "java"
+}
 
 repositories {
   mavenCentral()
 }
 
 dependencies {
-  testImplementation "junit:junit:4.13"
+  testImplementation platform("org.junit:junit-bom:5.10.0")
+  testImplementation "org.junit.jupiter:junit-jupiter"
   testImplementation "org.assertj:assertj-core:3.15.0"
 }
 
 test {
+  useJUnitPlatform()
+
   testLogging {
-    exceptionFormat = 'full'
+    exceptionFormat = "full"
     showStandardStreams = true
     events = ["passed", "failed", "skipped"]
   }

exercises/concept/karls-languages/src/test/java/LanguageListTest.java

@@ -1,57 +1,42 @@
-import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
 
-import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
 
 public class LanguageListTest {
 
     LanguageList languageList = new LanguageList();
 
     @Test
+    @Tag("task:1")
+    @DisplayName("The isEmpty method returns true when the list contains no languages")
     public void empty() {
         assertThat(languageList.isEmpty()).isTrue();
     }
 
     @Test
+    @Tag("task:2")
+    @DisplayName("The isEmpty method returns false after adding a language to the list")
     public void nonEmpty() {
         languageList.addLanguage("Java");
 
         assertThat(languageList.isEmpty()).isFalse();
     }
 
     @Test
-    public void addOneLanguage() {
-        languageList.addLanguage("Java");
-
-        assertThat(languageList.containsLanguage("Java")).isTrue();
-        assertThat(languageList.containsLanguage("Python")).isFalse();
-    }
-
-    @Test
-    public void addMultipleLanguages() {
-        languageList.addLanguage("Java");
-        languageList.addLanguage("Ruby");
-        languageList.addLanguage("C++");
-
-        assertThat(languageList.containsLanguage("Java")).isTrue();
-        assertThat(languageList.containsLanguage("Ruby")).isTrue();
-        assertThat(languageList.containsLanguage("C++")).isTrue();
-        assertThat(languageList.containsLanguage("Python")).isFalse();
-    }
-
-    @Test
+    @Tag("task:3")
+    @DisplayName("The removeLanguage method correctly removes a language from the list")
     public void removeLanguage() {
         languageList.addLanguage("Java");
-        languageList.addLanguage("Python");
-        languageList.addLanguage("Ruby");
-
-        languageList.removeLanguage("Python");
+        languageList.removeLanguage("Java");
 
-        assertThat(languageList.containsLanguage("Java")).isTrue();
-        assertThat(languageList.containsLanguage("Python")).isFalse();
-        assertThat(languageList.containsLanguage("Ruby")).isTrue();
+        assertThat(languageList.isEmpty()).isTrue();
     }
 
     @Test
+    @Tag("task:4")
+    @DisplayName("The firstLanguage method returns the first language that was added to the list")
     public void firstLanguage() {
         languageList.addLanguage("Java");
         languageList.addLanguage("Python");
@@ -61,6 +46,8 @@ public void firstLanguage() {
     }
 
     @Test
+    @Tag("task:5")
+    @DisplayName("The count method returns the number of languages in the list")
     public void countThree() {
         languageList.addLanguage("Java");
         languageList.addLanguage("Python");
@@ -70,18 +57,42 @@ public void countThree() {
     }
 
     @Test
+    @Tag("task:5")
+    @DisplayName("The count method returns 0 when the list is empty")
     public void countEmpty() {
         assertThat(languageList.count()).isEqualTo(0);
     }
 
     @Test
+    @Tag("task:6")
+    @DisplayName("The containsLanguage method returns true when the language is in the list")
+    public void containsLanguage() {
+        languageList.addLanguage("Java");
+
+        assertThat(languageList.containsLanguage("Java")).isTrue();
+    }
+
+    @Test
+    @Tag("task:6")
+    @DisplayName("The containsLanguage method returns false when the language is not in the list")
+    public void doesNotContainLanguage() {
+        languageList.addLanguage("Kotlin");
+
+        assertThat(languageList.containsLanguage("Java")).isFalse();
+    }
+
+    @Test
+    @Tag("task:7")
+    @DisplayName("The isExciting method returns true when the list contains Java")
     public void excitingLanguageListWithJava() {
         languageList.addLanguage("Java");
 
         assertThat(languageList.isExciting()).isTrue();
     }
 
     @Test
+    @Tag("task:7")
+    @DisplayName("The isExciting method returns true when the list contains Kotlin")
     public void excitingLanguageListWithKotlin() {
         languageList.addLanguage("Python");
         languageList.addLanguage("Kotlin");
@@ -90,6 +101,8 @@ public void excitingLanguageListWithKotlin() {
     }
 
     @Test
+    @Tag("task:7")
+    @DisplayName("The isExciting method returns false when the list contains neither Java nor Kotlin")
     public void boringLanguageList() {
         languageList.addLanguage("Python");
         languageList.addLanguage("Ruby");