Allow beans to be injected in tests even if they aren't used in the app

Fixes: #1749

extensions/arc/deployment/src/main/java/io/quarkus/arc/deployment/TestsAsBeanDefiningAnnotationsProcessor.java

@@ -0,0 +1,23 @@
+package io.quarkus.arc.deployment;
+
+import org.jboss.jandex.DotName;
+
+import io.quarkus.deployment.annotations.BuildProducer;
+import io.quarkus.deployment.annotations.BuildStep;
+import io.quarkus.deployment.builditem.LaunchModeBuildItem;
+import io.quarkus.runtime.LaunchMode;
+
+public class TestsAsBeanDefiningAnnotationsProcessor {
+
+    @BuildStep
+    public void testsAsBeanDefiningAnnotations(LaunchModeBuildItem launchMode,
+            BuildProducer<BeanDefiningAnnotationBuildItem> producer) {
+        if (launchMode.getLaunchMode() != LaunchMode.TEST) {
+            return;
+        }
+
+        producer.produce(new BeanDefiningAnnotationBuildItem(DotName.createSimple("io.quarkus.test.junit.QuarkusTest")));
+        producer.produce(new BeanDefiningAnnotationBuildItem(DotName.createSimple("org.junit.runner.RunWith")));
+    }
+
+}

integration-tests/main/src/main/java/io/quarkus/example/arc/UnusedBean.java

@@ -0,0 +1,7 @@
+package io.quarkus.example.arc;
+
+import javax.enterprise.context.ApplicationScoped;
+
+@ApplicationScoped
+public class UnusedBean {
+}

integration-tests/main/src/test/java/io/quarkus/example/test/BeanOnlyInTestCase.java

@@ -0,0 +1,22 @@
+package io.quarkus.example.test;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import javax.inject.Inject;
+
+import org.junit.jupiter.api.Test;
+
+import io.quarkus.example.arc.UnusedBean;
+import io.quarkus.test.junit.QuarkusTest;
+
+@QuarkusTest
+class BeanOnlyInTestCase {
+
+    @Inject
+    UnusedBean unusedBean;
+
+    @Test
+    void assertBeanIsInjected() {
+        assertNotNull(unusedBean);
+    }
+}