Develop Reference

How to mock ServletContext getResource?

i am currently writing Junit-Tests for on OData-Application (a hobby project). In there, I initialize a Servlet with the init() function. In order to receive specific application settings, i use the context.getResource() method.
Here is my code:
#Override
public void init(ServletConfig config) {
try {
super.init(config);
ServletContext context = getServletContext();
URL resourceUrl = context.getResource("/WEB-INF/config.properties");
if (resourceUrl == null) {
throw new ConfigurationException("Unable to find config.properties");
}
Path configFile = Paths.get(resourceUrl.toURI());
Now, I try to mock it. The Servlet itself is easy to mock, but im getting error when i try to mock the "getResource"-functionality. Here is my Junit-(beforeClass) Block:
public static ODataServlet getServlet() throws MalformedURLException {
if (servlet == null) {
servletConfig = new MockServletConfig();
MockServletContext context = new MockServletContext();
Path path = Paths.get("src/test/resources/config.properties");
when(context.getResource("/WEB-INF/config.properties")).thenReturn(path.toUri().toURL());
servlet = new ODataServlet(){
/**
*
*/
private static final long serialVersionUID = 1L;
public ServletContext getServletContext() {
return context; // return the mock
}
};
servlet.init(servletConfig);
}
return servlet;
}
Unfortunately, i always get the Exception:
org.mockito.exceptions.misusing.MissingMethodInvocationException:
when() requires an argument which has to be 'a method call on a mock'.
In the line
when(context.getResource("/WEB-INF/config.properties")).thenReturn(path.toUri().toURL());
I dont understand why. the context-Object is a MockedObject (MockServletContext).
Any advice ? Im also thinking changing everytghing to classloader.getResource as a workaround. But actually i like it like this ...
Any help would be much appreciated.
Sephir
UPDATE: SOLVED. After literally only a few minutes in here, some guys pointed out the Issue: MockServletContext context is from the Package org.springframework.mock.web which is not working with the Mockito.
After changing the MockServletContext
MockServletContext context = new MockServletContext();
to
context = Mockito.mock(ServletContext.class);
everything is working.
Big thanks to you Guys (!).

Spring IntegrationFlow is failing due to incorrect handle method

Hi I am trying to add Spring IntegrationFlow but dont know what is the error for following scenario.
My IntegrationConfig is as below
#Configuration
#EnableIntegration
#IntegrationComponentScan
public class IntegrationConfig {
#Bean
public IntegrationFlow sayHelloFlow(){
String uri = "http://localhost:8081/hellos";
return IntegrationFlows.from("integration.example.gateway.channel")
.filter("headers['operation'] == 'OPERATION_A'")
.<SearchRequest>handle((request) -> {
Map<String, String> header = new HashMap<String, String>();
header.put("a_header", request.getHeaders().get("initial_val", String.class));
SearchRequestB obj = new SearchRequestB(
request.getPayload()+"Modified",
header);
})
.handle(Http.outboundGateway(uri).httpMethod(HttpMethod.POST))
.get();
}
}
My IntegrationGateway class is
import org.springframework.integration.annotation.Gateway;
import org.springframework.integration.annotation.MessagingGateway;
#MessagingGateway
public interface IntegrationGateway {
#Gateway(requestChannel = "integration.example.gateway.channel")
public String canSearch(String message);
}
In the above problem is once I remove handle(Http.outboundGateway(uri).httpMethod(HttpMethod.POST)) line it works properly. and by keeping same line I am getting following error
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.integration.dsl.IntegrationFlow]: Factory method 'sayHelloFlow' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: The 'currentComponent' (com.integration.config.IntegrationConfig$$Lambda$793/0x0000000800567440#340cb97f) is a one-way 'MessageHandler' and it isn't appropriate to configure 'outputChannel'. This is the end of the integration flow.
I am wanted to call the another REST end point within this handle method.
What is wrong I am doing here
Thanks in advance !!

Your problem that handle(Message<?>) is really a one-way endpoint with a void return type and can be used only in the end of flow. That’s what that error about : since this endpoint cannot produce reply, there is no way to call the next endpoint in the flow. It is more suspicious that your code introduces that obj variable and does nothing with it.
See more in docs : https://docs.spring.io/spring-integration/docs/current/reference/html/dsl.html#java-dsl-class-cast.
To fix your solution we need to know if you want to call a rest with that obj or in parallel with this custom lambda.

Jmock/junit testing

If I have an SUT which handles an exception using a try/catch block, as follows:
public static void methodToBeTested() {
...
try {
desktop.browse(new URI("www.google.com"));
} catch (IOException e) {
//Display message to user and log out entry in app logs
}
...
}
Question is that should I test the condition from my unit tests that the IOException is thrown? (The method under test launches a URI in the default browser)
If yes, since I am not throwing the exception from this method, how do i unit test this condition when the desktop.browse() threw an IOException?
Any thoughts or suggestions? I am using JMock
Thanks!

Basically what you want to do is to
mockup Desktop and whenever you send a browse message to it (no matter what URI is used), instead of hitting that URI, it should throw an IOException.
I have used Jmock long time ago. JMock as far as I remember, has some limitations, for exmaple it does not provide a mechanism for mocking static methods. And I am not sure how easy it is to mock your browser class in jmock world.
However it is almost trivial to test this using jmockit, which supports all sorts of fancy mocking mechanisms (including static references, singletons etc). (I am mentioning jmockit because no matter what your browse class is, jmockit can mock it.)
Below is an excerpt from an example from their website:
package jmockit.tutorial.domain;
import org.apache.commons.mail.*;
import jmockit.tutorial.persistence.*;
import org.junit.*;
import mockit.*;
public final class MyBusinessService_ExpectationsAPI_Test
{
#Mocked(stubOutClassInitialization = true) final Database unused = null;
#Mocked SimpleEmail anyEmail;
#Test
public void doBusinessOperationXyz() throws Exception
{
final EntityX data = new EntityX(5, "abc", "abc#xpta.net");
final EntityX existingItem = new EntityX(1, "AX5", "someone#somewhere.com");
new Expectations() {{
(1) Database.find(withSubstring("select"), any);
result = existingItem; // automatically wrapped in a list of one item
}};
new MyBusinessService(data).doBusinessOperationXyz();
(2) new Verifications() {{ Database.persist(data); }};
(4) new Verifications() {{ email.send(); times = 1; }};
}
#Test(expected = EmailException.class)
public void doBusinessOperationXyzWithInvalidEmailAddress() throws Exception
{
new Expectations() {{
(3) email.addTo((String) withNotNull()); result = new EmailException();
}};
EntityX data = new EntityX(5, "abc", "someone#somewhere.com");
new MyBusinessService(data).doBusinessOperationXyz();
}
}
Above is the class under test and below is a the test which specifically tests (3) part of the above code. I think it is similar to what you are trying to do. Check it out please.
#Test(expected = EmailException.class)
public void doBusinessOperationXyzWithInvalidEmailAddress() throws Exception
{
new MockUp<Email>() {
#Mock
(3) Email addTo(String email) throws EmailException
{
assertNotNull(email);
throw new EmailException();
}
};
new MyBusinessService(data).doBusinessOperationXyz();
}
}
If you want to stick to jmock, it is fine. But then you need to give us more info about Desktop class and its browse method so that we can think about what we can do in jmock world.

Unit testing a Restlet extractor

I'm looking for some guidance on real unit testing for Restlet components, and specifically extractors. There is plenty of advice on running JUnit to rest entire endpoints, but being picky this is not unit testing, but integration testing. I really don't want to have set up an entire routing system and Spring just to check an extractor against a mock data repository.
The extractor looks like this:
public class CaseQueryExtractor extends Extractor {
protected int beforeHandle(Request request, Response response) {
extractFromQuery("offset", "offset", true);
extractFromQuery("limit", "limit", true);
// Stuff happens...
attributes.put("query", query);
return CONTINUE;
}
}
I'm thinking part of the virtue of Restlets is that its nice routing model ought to make unit testing easy, but I can't figure out what I need to do to actually exercise extractFromQuery and its friends, and all my logic that builds a query object, without mocking so much that I'm losing testing against a realistic web request.
And yes, I am using Spring, but I don't want to have to set the whole context for this -- I'm not integration testing as I haven't actually finished the app yet. I'm happy to inject manually, once I know what I need to make to get this method called.
Here's where I'm at now:
public class CaseQueryExtractorTest {
private class TraceRestlet extends Restlet {
// Does snothing, but prevents warning shouts
}
private CaseQueryExtractor extractor;
#Before
public void initialize() {
Restlet mock = new TraceRestlet();
extractor = new CaseQueryExtractor();
extractor.setNext(mock);
}
#Test
public void testBasicExtraction() {
Reference reference = new Reference();
reference.addQueryParameter("offset", "5");
reference.addQueryParameter("limit", "3");
Request request = new Request(Method.GET, reference);
Response response = extractor.handle(request);
extractor.handle(request, response);
CaseQuery query = (CaseQuery) request.getAttributes().get("query");
assertNotNull(query);
}
}
Which of course fails, as whatever set up I am doing isn't enough to make Restlets able to extract the query parameters.
Any thoughts or pointers?

There is a test module in Restlet that can provide you some hints about unit testing. See https://github.com/restlet/restlet-framework-java/tree/master/modules/org.restlet.test/src/org/restlet/test.
You can have a look at class HeaderTestCase (see https://github.com/restlet/restlet-framework-java/blob/master/modules/org.restlet.test/src/org/restlet/test/HeaderTestCase.java).
For information, if you use attributes from request, your unit test will pass ;-) See below:
public class CaseQueryExtractor extends Extractor {
protected int beforeHandle(Request request, Response response) {
extractFromQuery("offset", "offset", true);
extractFromQuery("limit", "limit", true);
// Stuff happens...
CaseQuery query = new CaseQuery();
Map<String,Object> attributes = request.getAttributes();
attributes.put("query", query);
return CONTINUE;
}
}
I don't know if you want to go further...
Hope it helps you,
Thierry

Updating Dropwizard config at runtime

Is it possible to have my app update the config settings at runtime? I can easily expose the settings I want in my UI but is there a way to allow the user to update settings and make them permanent ie save them to the config.yaml file? The only way I can see it to update the file by hand then restart the server which seems a bit limiting.

Yes. It is possible to reload the service classes at runtime.
Dropwizard by itself does not have the way to reload the app, but jersey has.
Jersey uses a container object internally to maintain the running application. Dropwizard uses the ServletContainer class of Jersey to run the application.
How to reload the app without restarting it -
Get a handle to the container used internally by jersey
You can do this by registering a AbstractContainerLifeCycleListener in Dropwizard Environment before starting the app. and implement its onStartup method as below -
In your main method where you start the app -
//getting the container instance
environment.jersey().register(new AbstractContainerLifecycleListener() {
#Override
public void onStartup(Container container) {
//initializing container - which will be used to reload the app
_container = container;
}
});
Add a method to your app to reload the app. It will take in the list of string which are the names of the service classes you want to reload. This method will call the reload method of the container with the new custom DropWizardConfiguration instance.
In your Application class
public static synchronized void reloadApp(List<String> reloadClasses) {
DropwizardResourceConfig dropwizardResourceConfig = new DropwizardResourceConfig();
for (String className : reloadClasses) {
try {
Class<?> serviceClass = Class.forName(className);
dropwizardResourceConfig.registerClasses(serviceClass);
System.out.printf(" + loaded class %s.\n", className);
} catch (ClassNotFoundException ex) {
System.out.printf(" ! class %s not found.\n", className);
}
}
_container.reload(dropwizardResourceConfig);
}
For more details see the example documentation of jersey - jersey example for reload
Consider going through the code and documentation of following files in Dropwizard/Jersey for a better understanding -
Container.java
ContainerLifeCycleListener.java
ServletContainer.java
AbstractContainerLifeCycleListener.java
DropWizardResourceConfig.java
ResourceConfig.java

No.
Yaml file is parsed at startup and given to the application as Configuration object once and for all. I believe you can change the file after that but it wouldn't affect your application until you restart it.
Possible follow up question: Can one restart the service programmatically?
AFAIK, no. I've researched and read the code somewhat for that but couldn't find a way to do that yet. If there is, I'd love to hear that :).

I made a task that reloads the main yaml file (it would be useful if something in the file changes). However, it is not reloading the environment. After researching this, Dropwizard uses a lot of final variables and it's quite hard to reload these on the go, without restarting the app.
class ReloadYAMLTask extends Task {
private String yamlFileName;
ReloadYAMLTask(String yamlFileName) {
super("reloadYaml");
this.yamlFileName = yamlFileName;
}
#Override
public void execute(ImmutableMultimap<String, String> parameters, PrintWriter output) throws Exception {
if (yamlFileName != null) {
ConfigurationFactoryFactory configurationFactoryFactory = new DefaultConfigurationFactoryFactory<ReportingServiceConfiguration>();
ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();
Validator validator = validatorFactory.getValidator();
ObjectMapper objectMapper = Jackson.newObjectMapper();
final ConfigurationFactory<ServiceConfiguration> configurationFactory = configurationFactoryFactory.create(ServiceConfiguration.class, validator, objectMapper, "dw");
File confFile = new File(yamlFileName);
configurationFactory.build(new File(confFile.toURI()));
}
}
}

You can change the configuration in the YAML and read it while your application is running. This will not however restart the server or change any server configurations. You will be able to read any changed custom configurations and use them. For example, you can change the logging level at runtime or reload other custom settings.
My solution -
Define a custom server command. You should use this command to start your application instead of the "server" command.
ArgsServerCommand.java
public class ArgsServerCommand<WC extends WebConfiguration> extends EnvironmentCommand<WC> {
private static final Logger LOGGER = LoggerFactory.getLogger(ArgsServerCommand.class);
private final Class<WC> configurationClass;
private Namespace _namespace;
public static String COMMAND_NAME = "args-server";
public ArgsServerCommand(Application<WC> application) {
super(application, "args-server", "Runs the Dropwizard application as an HTTP server specific to my settings");
this.configurationClass = application.getConfigurationClass();
}
/*
* Since we don't subclass ServerCommand, we need a concrete reference to the configuration
* class.
*/
#Override
protected Class<WC> getConfigurationClass() {
return configurationClass;
}
public Namespace getNamespace() {
return _namespace;
}
#Override
protected void run(Environment environment, Namespace namespace, WC configuration) throws Exception {
_namespace = namespace;
final Server server = configuration.getServerFactory().build(environment);
try {
server.addLifeCycleListener(new LifeCycleListener());
cleanupAsynchronously();
server.start();
} catch (Exception e) {
LOGGER.error("Unable to start server, shutting down", e);
server.stop();
cleanup();
throw e;
}
}
private class LifeCycleListener extends AbstractLifeCycle.AbstractLifeCycleListener {
#Override
public void lifeCycleStopped(LifeCycle event) {
cleanup();
}
}
}
Method to reload in your Application -
_ymlFilePath = null; //class variable
public static boolean reloadConfiguration() throws IOException, ConfigurationException {
boolean reloaded = false;
if (_ymlFilePath == null) {
List<Command> commands = _configurationBootstrap.getCommands();
for (Command command : commands) {
String commandName = command.getName();
if (commandName.equals(ArgsServerCommand.COMMAND_NAME)) {
Namespace namespace = ((ArgsServerCommand) command).getNamespace();
if (namespace != null) {
_ymlFilePath = namespace.getString("file");
}
}
}
}
ConfigurationFactoryFactory configurationFactoryFactory = _configurationBootstrap.getConfigurationFactoryFactory();
ValidatorFactory validatorFactory = _configurationBootstrap.getValidatorFactory();
Validator validator = validatorFactory.getValidator();
ObjectMapper objectMapper = _configurationBootstrap.getObjectMapper();
ConfigurationSourceProvider provider = _configurationBootstrap.getConfigurationSourceProvider();
final ConfigurationFactory<CustomWebConfiguration> configurationFactory = configurationFactoryFactory.create(CustomWebConfiguration.class, validator, objectMapper, "dw");
if (_ymlFilePath != null) {
// Refresh logging level.
CustomWebConfiguration webConfiguration = configurationFactory.build(provider, _ymlFilePath);
LoggingFactory loggingFactory = webConfiguration.getLoggingFactory();
loggingFactory.configure(_configurationBootstrap.getMetricRegistry(), _configurationBootstrap.getApplication().getName());
// Get my defined custom settings
CustomSettings customSettings = webConfiguration.getCustomSettings();
reloaded = true;
}
return reloaded;
}

Although this feature isn't supported out of the box by dropwizard, you're able to accomplish this fairly easy with the tools they give you.
Before I get started, note that this isn't a complete solution for the question asked as it doesn't persist the updated config values to the config.yml. However, this would be easy enough to implement yourself simply by writing to the config file from the application. If anyone would like to write this implementation feel free to open a PR on the example project I've linked below.
Code
Start off with a minimal config:
config.yml
myConfigValue: "hello"
And it's corresponding configuration file:
ExampleConfiguration.java
public class ExampleConfiguration extends Configuration {
private String myConfigValue;
public String getMyConfigValue() {
return myConfigValue;
}
public void setMyConfigValue(String value) {
myConfigValue = value;
}
}
Then create a task which updates the config:
UpdateConfigTask.java
public class UpdateConfigTask extends Task {
ExampleConfiguration config;
public UpdateConfigTask(ExampleConfiguration config) {
super("updateconfig");
this.config = config;
}
#Override
public void execute(Map<String, List<String>> parameters, PrintWriter output) {
config.setMyConfigValue("goodbye");
}
}
Also for demonstration purposes, create a resource which allows you to get the config value:
ConfigResource.java
#Path("/config")
public class ConfigResource {
private final ExampleConfiguration config;
public ConfigResource(ExampleConfiguration config) {
this.config = config;
}
#GET
public Response handleGet() {
return Response.ok().entity(config.getMyConfigValue()).build();
}
}
Finally wire everything up in your application:
ExampleApplication.java (exerpt)
environment.jersey().register(new ConfigResource(configuration));
environment.admin().addTask(new UpdateConfigTask(configuration));
Usage
Start up the application then run:
$ curl 'http://localhost:8080/config'
hello
$ curl -X POST 'http://localhost:8081/tasks/updateconfig'
$ curl 'http://localhost:8080/config'
goodbye
How it works
This works simply by passing the same reference to the constructor of ConfigResource.java and UpdateConfigTask.java. If you aren't familiar with the concept see here:
Is Java "pass-by-reference" or "pass-by-value"?
The linked classes above are to a project I've created which demonstrates this as a complete solution. Here's a link to the project:
scottg489/dropwizard-runtime-config-example
Footnote: I haven't verified this works with the built in configuration. However, the dropwizard Configuration class which you need to extend for your own configuration does have various "setters" for internal configuration, but it may not be safe to update those outside of run().
Disclaimer: The project I've linked here was created by me.