Add JUnit and Mockito test setup

build.gradle

@@ -18,6 +18,9 @@ dependencies {
     compileOnly 'io.papermc.paper:paper-api:26.2.build.129-stable'
     compileOnly 'com.sk89q.worldedit:worldedit-bukkit:7.4.5'
     compileOnly 'com.sk89q.worldguard:worldguard-bukkit:7.0.19'
+
+    testImplementation 'org.junit.jupiter:junit-jupiter:5.13.4'
+    testImplementation 'org.mockito:mockito-junit-jupiter:5.24.0'
 }
 
 java {
@@ -43,6 +46,10 @@ tasks.named('processResources') {
     }
 }
 
+tasks.named('test') {
+    useJUnitPlatform()
+}
+
 tasks.named('wrapper') {
     gradleVersion = '9.8.0'
     distributionType = Wrapper.DistributionType.BIN