Ensure QuarkusJsonbComponentInstanceCreator can be used in unit tests

Fixes: #4090

Author: geoand

extensions/jsonb/runtime/pom.xml

@@ -34,6 +34,11 @@
             <groupId>io.quarkus</groupId>
             <artifactId>quarkus-jsonp</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

extensions/jsonb/runtime/src/main/java/io/quarkus/jsonb/QuarkusJsonbComponentInstanceCreator.java

@@ -9,6 +9,7 @@
 import org.eclipse.yasson.spi.JsonbComponentInstanceCreator;
 
 import io.quarkus.arc.Arc;
+import io.quarkus.arc.ArcContainer;
 import io.quarkus.arc.InstanceHandle;
 
 public class QuarkusJsonbComponentInstanceCreator implements JsonbComponentInstanceCreator {
@@ -34,17 +35,26 @@ public void close() throws IOException {
     @Override
     public <T> T getOrCreateComponent(Class<T> componentClass) {
         return (T) components.computeIfAbsent(componentClass, c -> {
-            InstanceHandle<T> beanHandle = Arc.container().instance(componentClass);
+            ArcContainer container = Arc.container();
+            if (container == null) { // this class can be used in unit tests where Arc obviously doesn't run
+                return fallbackCreate(componentClass);
+            }
+
+            InstanceHandle<T> beanHandle = container.instance(componentClass);
             if (beanHandle.isAvailable()) {
                 beanHandles.add(beanHandle);
                 return beanHandle.get();
             }
-            try {
-                return componentClass.newInstance();
-            } catch (InstantiationException | IllegalAccessException e) {
-                throw new IllegalStateException("Cannot instantiate Jsonb component: " + componentClass, e);
-            }
+            return fallbackCreate(componentClass);
         });
     }
 
+    private <T> Object fallbackCreate(Class<T> componentClass) {
+        try {
+            return componentClass.newInstance();
+        } catch (InstantiationException | IllegalAccessException e) {
+            throw new IllegalStateException("Cannot instantiate Jsonb component: " + componentClass, e);
+        }
+    }
+
 }

extensions/jsonb/runtime/src/test/java/io/quarkus/jsonb/JsonbUnitTest.java

@@ -0,0 +1,51 @@
+package io.quarkus.jsonb;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.time.Instant;
+
+import javax.json.bind.JsonbBuilder;
+import javax.json.bind.adapter.JsonbAdapter;
+import javax.json.bind.annotation.JsonbProperty;
+import javax.json.bind.annotation.JsonbTypeAdapter;
+
+import org.junit.jupiter.api.Test;
+
+class JsonbUnitTest {
+
+    @Test
+    void testJsonbWorksProperly() {
+        SomeClass instance = JsonbBuilder.create().fromJson("{\"time\":1570039000}", SomeClass.class);
+        assertEquals(Instant.ofEpochSecond(1570039000), instance.getTime());
+    }
+
+    public static class SomeClass {
+
+        @JsonbProperty("time")
+        @JsonbTypeAdapter(EpochSecondsAdapter.class)
+        private Instant time;
+
+        public SomeClass() {
+        }
+
+        public Instant getTime() {
+            return time;
+        }
+
+        public void setTime(Instant time) {
+            this.time = time;
+        }
+
+        public static class EpochSecondsAdapter implements JsonbAdapter<Instant, Long> {
+            @Override
+            public Long adaptToJson(Instant obj) {
+                return obj.getEpochSecond();
+            }
+
+            @Override
+            public Instant adaptFromJson(Long obj) {
+                return Instant.ofEpochSecond(obj);
+            }
+        }
+    }
+}