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Java NegativeTest private method with Reflection to catch custom ApplicationException

So I'm testing a AccountService class with a mocked databaselayer.
In this AccountService class there is a private method that checks the input received from UI according to a regex.
The positive test I wrote is working fine:
#Test
public void testEmailPatroonCorrect() throws Exception{
//Correcte emails
List<String> emails = new ArrayList<>();
emails.add("user#domain.com");
emails.add("user#domain.co.in");
emails.add("user.name#domain.com");
emails.add("user_name#domain.com");
emails.add("username#yahoo.corporate.in");
Class<AccountService> foo = AccountService.class;
Method method = foo.getDeclaredMethod("checkEmailPatroon", String.class);
method.setAccessible(true);
assertThatCode(() -> {
for(String email : emails){
method.invoke(AccountService,email);
}}).doesNotThrowAnyException();
}
However for the negative test (a list with wrong email patterns) even with only one object in the list for simplicity
#Test
public void testEmailPatroonFout() throws Exception{
//Verkeerde emailpatronen
List<String> emails = new ArrayList<>();
emails.add(".username#yahoo.com");
Class<AccountService> foo = AccountService.class;
Method method = foo.getDeclaredMethod("checkEmailPatroon", String.class);
method.setAccessible(true);
assertThatThrownBy(()->{
for(String email : emails){
method.invoke(AccountService,email);
}
}).isInstanceOf(ApplicationException.class).hasMessage(ApplicationExceptionType.ONGELDIGE_EMAIL.getMsg());
}
The exception thrown during test is: java.lang.reflect.InvocationTargetException. In the application the ApplicationException gets caught just fine.
Question is how can I write a proper test for a list of wrong email patterns? (without using #VisibleForTesting functionality since it's a school project).
Many thanks!

The InvocationTargetException wraps the exception thrown within the reflectively invoked method. So you may catch the InvocationTargetException and rethrow its cause, but I’d put that into a utility method, like
public interface TestMethod<D,A> {
void invoke(D d, A a) throws Throwable;
}
static <D,A> TestMethod<D,A> method(
Class<D> declarer, String name, Class<A> argType) throws ReflectiveOperationException {
Method method = declarer.getDeclaredMethod(name, argType);
method.setAccessible(true);
return (d,a) -> {
try {
method.invoke(d, a);
} catch(InvocationTargetException ex) {
throw ex.getTargetException();
}
};
}
which you can use like
#Test
public void testEmailPatroonFout() throws Exception{
//Verkeerde emailpatronen
List<String> emails = new ArrayList<>();
emails.add(".username#yahoo.com");
TestMethod<AccountService, String> method
= method(AccountService.class, "checkEmailPatroon", String.class);
assertThatThrownBy(() -> {
for(String email : emails){
method.invoke(AccountService, email);
}
}).isInstanceOf(ApplicationException.class)
.hasMessage(ApplicationExceptionType.ONGELDIGE_EMAIL.getMsg());
}
The shape of the TestMethod interface allows the alternative implementation like
static <D,A> TestMethod<D,A> method(
Class<D> declarer, String name, Class<A> argType) throws ReflectiveOperationException {
Method method = declarer.getDeclaredMethod(name, argType);
method.setAccessible(true);
return MethodHandleProxies.asInterfaceInstance(
TestMethod.class, MethodHandles.lookup().unreflect(method));
}

Thanks to Holger I was able to write a working test for it's purpose.
#Test
public void testEmailPatroonFoutLoop() throws Throwable {
//Verkeerde emailpatronen
List<String> wrongEmails = new ArrayList<>();
wrongEmails.add(".username#yahoo.com");
wrongEmails.add("username#yahoo.com.");
wrongEmails.add("usernameyahoo.com");
wrongEmails.add("username#yahoo.c");
wrongEmails.add("use..rname#yahoo.com");
Class<AccountService> foo = AccountService.class;
Method method = foo.getDeclaredMethod("checkEmailPatroon", String.class);
method.setAccessible(true);
int countedWrongEmails = 0;
for(String email : wrongEmails){
try{
method.invoke(accServ,email);
}
catch (InvocationTargetException ie){
Exception e = (Exception) ie.getTargetException();
if(e.getMessage().equals(ApplicationExceptionType.ONGELDIGE_EMAIL.getMsg())){
countedWrongEmails++;
}
}
}
assertThat(countedWrongEmails).isEqualTo(wrongEmails.size());
}
Although I see the benefits and elegance of writing a TestMethod interface, I however do not yet possess the knowledge to grasp it's complexity. So I will stick to this test that I'll be able to explain on the verbal exam.

Mocking a Vertx.io async handler

when I was sync I wrote unit tests mocking the persistence part and check the caller's behavior. Here is an example about what I usually did:
#Mock
private OfferPersistenceServiceImpl persistenceService;
#Inject
#InjectMocks
private OfferServiceImpl offerService;
...
#Test
public void createInvalidOffer() {
offer = new Offer(null, null, null, null, null, 4, 200D, 90D);
String expectedMessage = Offer.class.getName() + " is not valid: " + offer.toString();
Mockito.when(persistenceService.create(offer)).thenThrow(new IllegalArgumentException(expectedMessage));
Response response = offerService.create(offer);
Mockito.verify(persistenceService, Mockito.times(1)).create(offer);
Assert.assertEquals(INVALID_INPUT, response.getStatus());
String actualMessage = response.getEntity().toString();
Assert.assertEquals(expectedMessage, actualMessage);
}
But now I fell in love with Vertx.io (to which I am pretty new) and I want to be async. Nice. But Vertx has handlers, so the new persistence component to mock looks like this:
...
mongoClient.insert(COLLECTION, offer, h-> {
...
});
So I am guessing how to mock handler h to tests class who's using that mongoClient or even if it is the right way to test with Vertx.io. I am using vertx.io 3.5.0, junit 4.12 and mockito 2.13.0. Thanks.
Update
I tried to follow tsegimond suggestion but I can't get how Mockito's Answer and ArgumentCaptor can help me. Here is what I tried so far.
Using ArgumentCaptor:
JsonObject offer = Mockito.mock(JsonObject.class);
Mockito.when(msg.body()).thenReturn(offer);
Mockito.doNothing().when(offerMongo).validate(offer);
RuntimeException rex = new RuntimeException("some message");
...
ArgumentCaptor<Handler<AsyncResult<String>>> handlerCaptor =
ArgumentCaptor.forClass(Handler.class);
ArgumentCaptor<AsyncResult<String>> asyncResultCaptor =
ArgumentCaptor.forClass(AsyncResult.class);
offerMongo.create(msg);
Mockito.verify(mongoClient,
Mockito.times(1)).insert(Mockito.anyString(), Mockito.any(), handlerCaptor.capture());
Mockito.verify(handlerCaptor.getValue(),
Mockito.times(1)).handle(asyncResultCaptor.capture());
Mockito.when(asyncResultCaptor.getValue().succeeded()).thenReturn(false);
Mockito.when(asyncResultCaptor.getValue().cause()).thenReturn(rex);
Assert.assertEquals(Json.encode(rex), msg.body().encode());
and using Answer:
ArgumentCaptor<AsyncResult<String>> handlerCaptor =
ArgumentCaptor.forClass(AsyncResult.class);
AsyncResult<String> result = Mockito.mock(AsyncResult.class);
Mockito.when(result.succeeded()).thenReturn(true);
Mockito.when(result.cause()).thenReturn(rex);
Mockito.doAnswer(new Answer<MongoClient>() {
#Override
public MongoClient answer(InvocationOnMock invocation) throws Throwable {
((Handler<AsyncResult<String>>)
invocation.getArguments()[2]).handle(handlerCaptor.capture());
return null;
}
}).when(mongoClient).insert(Mockito.anyString(), Mockito.any(),
Mockito.any());
userMongo.create(msg);
Assert.assertEquals(Json.encode(rex), msg.body().encode());
And now I got confused. Is there a way to mock an AsyncResult to let it return false on succeed()?

Finally I got some times to investigate and I made it. Here is my solution.
#RunWith(PowerMockRunner.class)
#PowerMockRunnerDelegate(VertxUnitRunner.class)
#PrepareForTest({ MongoClient.class })
public class PersistenceTest {
private MongoClient mongo;
private Vertx vertx;
#Before
public void initSingleTest(TestContext ctx) throws Exception {
vertx = Vertx.vertx();
mongo = Mockito.mock(MongoClient.class);
PowerMockito.mockStatic(MongoClient.class);
PowerMockito.when(MongoClient.createShared(Mockito.any(), Mockito.any())).thenReturn(mongo);
vertx.deployVerticle(Persistence.class, new DeploymentOptions(), ctx.asyncAssertSuccess());
}
#SuppressWarnings("unchecked")
#Test
public void loadSomeDocs(TestContext ctx) {
Doc expected = new Doc();
expected.setName("report");
expected.setPreview("loremipsum");
Message<JsonObject> msg = Mockito.mock(Message.class);
Mockito.when(msg.body()).thenReturn(JsonObject.mapFrom(expected));
JsonObject result = new JsonObject().put("name", "report").put("preview", "loremipsum");
AsyncResult<JsonObject> asyncResult = Mockito.mock(AsyncResult.class);
Mockito.when(asyncResult.succeeded()).thenReturn(true);
Mockito.when(asyncResult.result()).thenReturn(result);
Mockito.doAnswer(new Answer<AsyncResult<JsonObject>>() {
#Override
public AsyncResult<JsonObject> answer(InvocationOnMock arg0) throws Throwable {
((Handler<AsyncResult<JsonObject>>) arg0.getArgument(3)).handle(asyncResult);
return null;
}
}).when(mongo).findOne(Mockito.any(), Mockito.any(), Mockito.any(), Mockito.any());
Async async = ctx.async();
vertx.eventBus().send("persistence", new JsonObject(), msgh -> {
if (msgh.failed()) {
System.out.println(msgh.cause().getMessage());
}
ctx.assertTrue(msgh.succeeded());
ctx.assertEquals(expected, Json.decodeValue(msgh.result().body().toString(), Doc.class));
async.complete();
});
async.await();
}
}
Use Powemockito to mock the MongoClient.createShared static method, so you'll have your mock when verticle starts. Mocking async handler is a bit of code to write. As you can see mocking start at Message<JsonObject> msg = Mockito.mock(Message.class); and ends at Mockito.doAnswer(new Answer.... In the Answer's method pick the handler param and force it to handle your async result then you're done.

Normally, I'd use a comment to post this, but formatting gets lost. The accepted solution is works great, just note that it can be simplified a bit using Java 8+, and you can use your actual objects instead of JSON.
doAnswer((Answer<AsyncResult<List<Sample>>>) arguments -> {
((Handler<AsyncResult<List<Sample>>>) arguments.getArgument(1)).handle(asyncResult);
return null;
}).when(sampleService).findSamplesBySampleFilter(any(), any());
getArgument(1), refers to the index of the handler argument in a method such as:
#Fluent
#Nonnull
SampleService findSamplesBySampleFilter(#Nonnull final SampleFilter sampleFilter,
#Nonnull final Handler<AsyncResult<List<Sample>>> resultHandler);

How to test Java web service with JUnit?

I need to test a service by JUnit.
Here is my code :
public class AdviesBoxTestDaoImpl {
private SearchDaoImpl searchDaoImpl;
private SearchParametersDto searchParametersDto;
JSONObject jsonObject;
#Before
public void loadJsonFile(){
try{
ObjectMapper mapper = new ObjectMapper();
searchParametersDto = mapper.readValue(new File("D:\\productsData.json"), SearchParametersDto.class);
}
catch(Exception e){
}
}
#Test
public void testsDemoMethod() throws SQLException {
System.out.println(searchParametersDto.toString());
assertEquals( "Products saved successfully",
searchDaoImpl.inTable(searchParametersDto));
}
}
Result of my service is message as "Products saved successfully" in String which is I am comparing here. Each time I run the test case , I get the NullPointerException Error.
What changes I should make in the code so that I can test the service correctly?

You should not catch the exception in the loadJsonFile() method. It hides any exception and you don't see the real cause of failing tests. Here is an improved loadJsonFile().
#Before
public void loadJsonFile() throws Exception {
ObjectMapper mapper = new ObjectMapper();
searchParametersDto = mapper.readValue(
new File("D:\\productsData.json"),
SearchParametersDto.class
);
}

PowerMock's expectNew() isn't mocking a constructor as expected

I'm trying to learn the ins and outs of various mocking libraries and PowerMock(specifically the EasyMock extension) is next on the list. I'm attempting to mock a constructor and the examples provided don't have the same response when I try to replicate them. As far as I can tell, it never mocks the constructor and just proceeds as if it were normal.
This is the test class:
#RunWith(PowerMockRunner.class)
#PrepareForTest({Writer.class})
public class FaultInjectionSituationTest {
#Test
public void testActionFail() throws Exception {
FaultInjectionSituation fis = new FaultInjectionSituation();
PowerMock.expectNew(Writer.class, "test")
.andThrow(new IOException("thrown from mock"));
PowerMock.replay(Writer.class);
System.out.println(fis.action());
PowerMock.verify(Writer.class);
}
}
I've tried replacing the "test" with an EasyMock.isA(String.class), but it yielded the same results.
This is the FaultInjectionSituation:
public class FaultInjectionSituation {
public String action(){
Writer w;
try {
w = new Writer("test");
} catch (IOException e) {
System.out.println("thrown: " + e.getMessage());
return e.getLocalizedMessage();
}
return "returned without throw";
}
}
The "Writer" is nothing more than a shell of a class:
public class Writer {
public Writer(String s) throws IOException {
}
public Writer() throws IOException{
}
}
When the test is run, it prints out "returned without throw", indicating the exception was never thrown.

You need to prepare the class that is calling the constructor as well, so PowerMock knows to expect a mocked constructor call. Try updating your code with the following:
#RunWith(PowerMockRunner.class)
#PrepareForTest({Writer.class, FaultInjectionSituation.class})
public class FaultInjectionSituationTest {
// as before
}

You need to first create a mock object:
Writer mockWriter = PowerMock.createMock(Writer.class)
PowerMock.expectNew(Writer.class, "test").andReturn(mockWriter)

How do I write a unit test to cover the case where an IOException is thrown?

I have the following class:
public class FileLoader {
private Map<Brand, String> termsOfUseText = new HashMap<Brand, String>();
public void load() {
for (Brand brand : Brand.values()) {
readAndStoreTermsOfUseForBrand(brand);
}
}
private void readAndStoreTermsOfUseForBrand(Brand brand) {
String resourceName = "termsOfUse/" + brand.name().toLowerCase() + ".txt";
InputStream in = this.getClass().getClassLoader().getResourceAsStream(resourceName);
try {
String content = IOUtils.toString(in);
termsOfUseText.put(brand, content);
} catch (IOException e) {
throw new IllegalStateException(String.format("Failed to find terms of use source file %s", resourceName),e);
}
}
public String getTextForBrand(Brand brand) {
return termsOfUseText.get(brand);
}
}
Brand is an enum, and I need all the valid .txt files to be on the classpath. How do I make the IOException occur, given that the Brand enum contains all the valid brands and therfore all the .txt files for them exist?
Suggestions around refactoring the current code are welcome if it makes it more testable!

Three options I see right off:
Use PowerMock to mock IOUtils.toString(). I consider PowerMock to be quite a last resort. I'd rather refactor the source to something a little more test-friendly.
Extract the IOUtils call to a protected method. Create a test-specific subclass of your class that overrides this method and throws the IOException.
Extract the InputStream creation to a protected method. Create a test-specific subclass to override the method and return a mock InputStream.

I would suggest a bit of refactoring. All your methods are void, this usually means they are not functional.
For example, you can extract this functionality:
private String readTermsOfUseForBrand(InputStream termsOfUserIs) {
try {
String content = IOUtils.toString(in);
return content;
} catch (IOException e) {
throw new IllegalStateException(String.format("Failed to find terms of use source file %s", resourceName), e);
}
return null;
}
So that we can assert on the String result in our tests.
Of course this is not functional code, as it reads from an Input Stream. And it does so with IOUtils.toString() method that cannot be mocked easily (well, there's PowerMock but as Ryan Stewart said it's the last resort).
To test IO exceptions you can create a failing input stream (tested with JDK7):
public class FailingInputStream extends InputStream {
#Override
public int read() throws IOException {
throw new IOException("Test generated exception");
}
}
And test like that:
#Test
public void testReadTermsOfUseForBrand() {
FileLoader instance = new FileLoader();
String result = instance.readTermsOfUseForBrand(new FailingInputStream());
assertNull(result);
}

Missing file will cause NullPointerException because getResourceAsStream will return null and you will have in==null. IOException in this case may actually be pretty rare. If it's critical for you to see it, I can only think of instrumenting this code to throw it if code is executed in test scope. But is it really that important?

I would use a mock to accomplish this.
Example (untested, just to give you some thought):
#Test(expected=IllegalStateException.class)
public void testThrowIOException() {
PowerMockito.mockStatic(IOUtils.class);
PowerMockito.when(IOUtils.toString()).thenThrow(
new IOException("fake IOException"));
FileLoader fileLoader = new FileLoader();
Whitebox.invokeMethod(fileLoader,
"readAndStoreTermsOfUseForBrand", new Brand(...));
// If IllegalStateException is not thrown then this test case fails (see "expected" above)
}

Code below is completely untested
To cause the IOException use:
FileInputStream in = this.getClass().getClassLoader().getResourceAsStream(resourceName);
in.mark(0);
//read some data
in.reset(); //IOException
To test the IOException case use:
void test
{
boolean success = false;
try
{
//code to force ioException
}
catch(IOException ioex)
{
success = true;
}
assertTrue(success);
}
In JUnit4
#Test(expected=IOException.class)
void test
{
//code to force ioException
}
Other JUnit
void test
{
try
{
//code to force IOException
fail("If this gets hit IO did not occur, fail test");
}
catch(IOException ioex)
{
//success!
}
}