Adding extension for JUnit5 support

CHANGELOG.md

@@ -12,6 +12,7 @@
 #### Improvements
 * Fix #2233: client.service().getUrl(..) should be able to fetch URL for ClusterIP based services
 * Fix #2278: Added type parameters for KubernetesList in KubernetesClient + test verifying waitUntilCondition **always** retrieves resource from server
+* Fix #2320: Added JUnit5 extension for mocking KubernetesClient in tests using @EnableKubernetesMockClient
 
 #### Dependency Upgrade
 

README.md

@@ -346,7 +346,36 @@ Then you can use the server like:
       assertTrue(closeLatch.await(1, TimeUnit.MINUTES));
     }
 
+### JUnit5 support through extension
+
+You can use KubernetesClient mocking mechanism with JUnit5. Since it doesn't support `@Rule` and `@ClassRule` there is dedicated annotation `@EnableKubernetesMockClient`.
+If you would like to create instance of mocked `KubernetesClient` for each test (JUnit4 `@Rule`) you need to declare instance of `KubernetesClient` as shown below.
+
+    @EnableKubernetesMockClient
+    class ExampleTest {
+
+        KubernetesClient client;
+
+        @Test
+        public void testInStandardMode() {
+            ...
+        }
+    }
 
+In case you would like to define static instance of mocked server per all the test (JUnit4 `@ClassRule`) you need to declare instance of `KubernetesClient` as shown below.
+You can also enable crudMode by using annotation field `crud`.
+
+    @EnableKubernetesMockClient(crud = true)
+    class ExampleTest {
+
+        static KubernetesClient client;
+
+        @Test
+        public void testInCrudMode() {
+            ...
+        }
+    }
+
 ## Compatibility Matrix
 
 |                           | Kubernetes 1.4.9 | Kubernetes 1.6.0 | Kubernetes 1.7.0  | Kubernetes 1.9.0  | Kubernetes 1.10.0 | Kubernetes 1.11.0 | Kubernetes 1.12.0 | Kubernetes 1.14.2 | Kubernetes 1.15.3 | Kubernetes 1.17.0 |

kubernetes-server-mock/pom.xml

@@ -65,5 +65,9 @@
       <version>${slf4j.version}</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-api</artifactId>
+    </dependency>
   </dependencies>
 </project>

kubernetes-server-mock/src/main/java/io/fabric8/kubernetes/client/server/mock/EnableKubernetesMockClient.java

@@ -0,0 +1,40 @@
+package io.fabric8.kubernetes.client.server.mock;
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+/**
+ * Annotation that is used for enabling KubernetesMockServerExtension JUnit5 extension.
+ * You may set here two parameters of `KubernetesServer`: crudMode and https
+ */
+@Target({ TYPE, METHOD, ANNOTATION_TYPE })
+@Retention(RUNTIME)
+@ExtendWith(KubernetesMockServerExtension.class)
+public @interface EnableKubernetesMockClient {
+
+	boolean https() default true;
+
+	boolean crud() default false;
+}

kubernetes-server-mock/src/main/java/io/fabric8/kubernetes/client/server/mock/KubernetesMockServerExtension.java

@@ -0,0 +1,115 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.fabric8.kubernetes.client.server.mock;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.util.HashMap;
+import java.util.Optional;
+
+import io.fabric8.kubernetes.client.KubernetesClient;
+import io.fabric8.kubernetes.client.NamespacedKubernetesClient;
+import io.fabric8.mockwebserver.Context;
+import okhttp3.mockwebserver.MockWebServer;
+import org.junit.jupiter.api.extension.AfterAllCallback;
+import org.junit.jupiter.api.extension.AfterEachCallback;
+import org.junit.jupiter.api.extension.BeforeAllCallback;
+import org.junit.jupiter.api.extension.BeforeEachCallback;
+import org.junit.jupiter.api.extension.ExtensionContext;
+
+/**
+ * The class that implements JUnit5 extension mechanism. You can use it directly in your JUnit test
+ * by annotating it with `@ExtendWith(KubernetesMockServerExtension.class)` or through
+ * @EnableKubernetesMockClient annotation
+ */
+public class KubernetesMockServerExtension implements AfterEachCallback, AfterAllCallback, BeforeEachCallback, BeforeAllCallback {
+
+  private KubernetesMockServer mock;
+  private NamespacedKubernetesClient client;
+
+  @Override
+  public void afterEach(ExtensionContext context) throws Exception {
+    Optional<Class<?>> optClass = context.getTestClass();
+    if (optClass.isPresent()) {
+      Class<?> testClass = optClass.get();
+      if (findField(testClass, true) == null) {
+        destroy();
+      }
+    }
+  }
+
+  @Override
+  public void afterAll(ExtensionContext context) throws Exception {
+    destroy();
+  }
+
+  @Override
+  public void beforeEach(ExtensionContext context) throws Exception {
+    setKubernetesClientField(context, false);
+  }
+
+  @Override
+  public void beforeAll(ExtensionContext context) throws Exception {
+    setKubernetesClientField(context, true);
+  }
+
+  private void setKubernetesClientField(ExtensionContext context, boolean isStatic) throws IllegalAccessException {
+    Optional<Class<?>> optClass = context.getTestClass();
+    if (optClass.isPresent()) {
+      Class<?> testClass = optClass.get();
+      Field[] fields = testClass.getDeclaredFields();
+      for (Field f : fields) {
+        if (f.getType() == KubernetesClient.class && Modifier.isStatic(f.getModifiers()) == isStatic) {
+          createKubernetesClient(testClass);
+          f.setAccessible(true);
+          if (isStatic) {
+            f.set(null, client);
+          } else {
+            Optional<Object> optTestInstance = context.getTestInstance();
+            if (optTestInstance.isPresent())
+              f.set(optTestInstance.get(), client);
+          }
+        }
+      }
+    }
+  }
+
+  private void createKubernetesClient(Class<?> testClass) {
+    EnableKubernetesMockClient a = testClass.getAnnotation(EnableKubernetesMockClient.class);
+    mock = a.crud()
+      ? new KubernetesMockServer(new Context(), new MockWebServer(), new HashMap<>(), new KubernetesCrudDispatcher(), a.https())
+      : new KubernetesMockServer(a.https());
+    mock.init();
+    client = mock.createClient();
+  }
+
+  private void destroy() {
+    mock.destroy();
+    client.close();
+  }
+
+  private Field findField(Class<?> testClass, boolean isStatic) {
+    Field[] fields = testClass.getDeclaredFields();
+    for (Field f : fields) {
+      if (f.getType() == KubernetesClient.class && Modifier.isStatic(f.getModifiers()) == isStatic) {
+        return f;
+      }
+    }
+    return null;
+  }
+
+}

kubernetes-server-mock/src/test/java/io/fabric8/kubernetes/client/server/mock/KubernetesMockServerExtensionStaticTests.java

@@ -0,0 +1,32 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.fabric8.kubernetes.client.server.mock;
+
+import io.fabric8.kubernetes.client.KubernetesClient;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+@EnableKubernetesMockClient(crud = true)
+public class KubernetesMockServerExtensionStaticTests {
+
+	static KubernetesClient client;
+
+	@Test
+	void testExample() {
+		Assertions.assertNotNull(client);
+	}
+}

kubernetes-server-mock/src/test/java/io/fabric8/kubernetes/client/server/mock/KubernetesMockServerExtensionTests.java

@@ -0,0 +1,32 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.fabric8.kubernetes.client.server.mock;
+
+import io.fabric8.kubernetes.client.KubernetesClient;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+@EnableKubernetesMockClient(crud = true)
+public class KubernetesMockServerExtensionTests {
+
+	KubernetesClient client;
+
+	@Test
+	void testExample() {
+		Assertions.assertNotNull(client);
+	}
+}