test: add JUnit

.github/workflows/test.yaml

@@ -0,0 +1,17 @@
+on:
+  push:
+    branches:
+      - main
+      - pull-req/**
+      - release/**
+      - hotfix/**
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 21
+      - run: ./gradlew build

build.gradle

@@ -14,6 +14,22 @@ jar {
   }
 }
 
+repositories {
+  mavenCentral()
+}
+
+test {
+  reports.html.required = false
+  dependsOn cleanTest
+  testLogging.showStandardStreams = true
+}
+
+dependencies {
+  // https://mvnrepository.com/artifact/junit/junit
+  testImplementation 'org.junit.jupiter:junit-jupiter:5.7.1'
+  testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
+}
+
 tasks.withType(JavaCompile) { // gradle's default is not utf-8
   options.encoding = 'UTF-8'
 }

src/test/java/HelloTest.java

@@ -0,0 +1,9 @@
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+public class HelloTest {
+  @Test
+  public void TestHelloMain () {
+    assertNotNull(new Hello());
+  }
+}