Small improvements to Jupiter extension code style (#947)

* Small improvements to Jupiter extension code style

Follow up to #887

* Only raise exception if annotated field is not Startable

Author: kiview

modules/junit-jupiter/src/main/java/org/testcontainers/junit/jupiter/TestcontainersExtension.java

@@ -1,5 +1,6 @@
 package org.testcontainers.junit.jupiter;
 
+import lombok.Getter;
 import org.junit.jupiter.api.extension.BeforeEachCallback;
 import org.junit.jupiter.api.extension.ExtensionConfigurationException;
 import org.junit.jupiter.api.extension.ExtensionContext;
@@ -30,7 +31,7 @@ public void postProcessTestInstance(final Object testInstance, final ExtensionCo
         store.put(TEST_INSTANCE, testInstance);
 
         findSharedContainers(testInstance)
-            .forEach(adapter -> store.getOrComputeIfAbsent(adapter.key, k -> adapter.start()));
+            .forEach(adapter -> store.getOrComputeIfAbsent(adapter.getKey(), k -> adapter.start()));
     }
 
     @Override
@@ -39,13 +40,13 @@ public void beforeEach(final ExtensionContext context) {
             .parallelStream()
             .flatMap(this::findRestartContainers)
             .forEach(adapter -> context.getStore(NAMESPACE)
-                .getOrComputeIfAbsent(adapter.key, k -> adapter.start()));
+                .getOrComputeIfAbsent(adapter.getKey(), k -> adapter.start()));
     }
 
     private Set<Object> collectParentTestInstances(final ExtensionContext context) {
         Set<Object> testInstances = new LinkedHashSet<>();
         Optional<ExtensionContext> current = Optional.of(context);
-        while(current.isPresent()) {
+        while (current.isPresent()) {
             ExtensionContext ctx = current.get();
             Object testInstance = ctx.getStore(NAMESPACE).remove(TEST_INSTANCE);
             if (testInstance != null) {
@@ -83,7 +84,18 @@ private Predicate<Field> isRestartContainer() {
     }
 
     private static Predicate<Field> isContainer() {
-        return field -> Startable.class.isAssignableFrom(field.getType()) && AnnotationSupport.isAnnotated(field, Container.class);
+        return field -> {
+            boolean isAnnotatedWithContainer = AnnotationSupport.isAnnotated(field, Container.class);
+            if (isAnnotatedWithContainer) {
+                boolean isStartable = Startable.class.isAssignableFrom(field.getType());
+
+                if (!isStartable) {
+                    throw new ExtensionConfigurationException("Annotation is only supported for Startable types");
+                }
+                return true;
+            }
+            return false;
+        };
     }
 
     private static StoreAdapter getContainerInstance(final Object testInstance, final Field field) {
@@ -103,6 +115,7 @@ private static StoreAdapter getContainerInstance(final Object testInstance, fina
      */
     private static class StoreAdapter implements CloseableResource {
 
+        @Getter
         private String key;
 
         private Startable container;

modules/junit-jupiter/src/test/java/org/testcontainers/junit/jupiter/WrongAnnotationUsageTests.java

@@ -0,0 +1,20 @@
+package org.testcontainers.junit.jupiter;
+
+
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+
+@Disabled
+@Testcontainers
+class WrongAnnotationUsageTests {
+
+    @Container
+    private String notStartable = "foobar";
+
+    @Test
+    void extension_throws_exception() {
+        assert true;
+    }
+
+}