We Keep Coding

Mockito mocking a new instance call with parameters

For school purposes I am creating an application that's working with a stock API.
I am trying to write a test for a method that gets all the stock data of the last 10 years. Instead of actually getting all that data, I want to throw an exception.
The method I Want to test:
#Override
public List<StockData> getAllTeslaStockData() throws AlphaVantageException {
List<StockData> stockData;
AlphaVantageConnector apiConnector = new AlphaVantageConnector(APIKEY, TIMEOUT);
TimeSeries stockTimeSeries = new TimeSeries(apiConnector);
try {
Daily responseDaily = stockTimeSeries.daily("TSLA", OutputSize.FULL);
stockData = responseDaily.getStockData();
} catch (AlphaVantageException e) {
LOGGER.log(Level.SEVERE, "something went wrong: ", e);
throw e;
}
return stockData;
}
The stockTimeSeries.daily(....) call can throw the AlphaVantageException.
I've mocked the TimeSeries class like this:
TimeSeries stockTimeSeries = mock(TimeSeries.class);
In my test class I want to mock this call, and return an exception instead of actual data.
when(stockTimeSeries.daily("TSLA", OutputSize.FULL)).thenThrow(new AlphaVantageException("No stock data available"));
Regardless of how I am trying to mock this bit of code, it'll never throw the exception. It will always just execute the code, and return valid stock data, instead of throwing the exception like i've tried to do.
How can I mock this bit of code, so that itll throw the exception I am expecting for my tests.
The AlphaVantageConnector, TimeSeries and Daily classes are part of a library used to access the stock API, so I can't change these classes.
I am using JUnit 4.12 and Mockito to try and achieve this.

You can use thenThrow() method. Below is the example
#Test(expected = NullPointerException.class)
public void whenConfigNonVoidRetunMethodToThrowEx_thenExIsThrown() {
MyDictionary dictMock = mock(MyDictionary.class);
when(dictMock.getMeaning(anyString()))
.thenThrow(NullPointerException.class);
dictMock.getMeaning("word");

The TimeSeries object is created in the method itself, so you can't mock it - mocking is intended to mock members.
What you can do is to do something like
class YourClass {
private Supplier<TimeSeries> seriesCreator = () -> {
return new TimeSeries(new AlphaVantageConnector(APIKEY, TIMEOUT));
}
which you use to create the series in your method
#Override
public List<StockData> getAllTeslaStockData() throws AlphaVantageException {
TimeSeries stockTimeSeries = seriesCreator.get();
Now you can mock that Supplier.
#Mock Supplier<TimeSeries> seriesCreatorMock;
#InjectMocks MyClass sut;
and in your test
#Test(expected = AlphaVantageException.class)
void testException() {
when(seriesCreatorMock.get()).thenThrow(new AlphaVantageException());
sut.getAllTeslaStockData()
}
EDIT: as suggested by Angkur in the comments, the clean way would be to
class SeriesCreator implements Supplier<TimeSeries> {
public TimeSeries get() {
return new TimeSeries(new AlphaVantageConnector(APIKEY, TIMEOUT));
}
}
class YourClass {
private Supplier<TimeSeries> seriesCreator = new SeriesCreator();
// ...

The code in the main class is creating a new instance of TimeSeries which it will use every time this method is called, so the mocked TimeSeries object is not getting used at all.
TimeSeries stockTimeSeries = new TimeSeries(apiConnector); // --> This is not getting mocked
try {
Daily responseDaily = stockTimeSeries.daily("TSLA", OutputSize.FULL);
stockData = responseDaily.getStockData();
}
You should create another method in your class (or even a separate class if it better satisfies the SOLID principles) which returns you the TimeSeries object. Something like:-
<access modifier> TimeSeries getTimeSeries(...) {
}
and then this method should be mocked in the Junit, and when mocked, it should return the Mocked TimeSeries reference (which is created in TimeSeries stockTimeSeries = mock(TimeSeries.class); ). You would need to use .spy() on the main class (unless you are using a different class to create TimeSeries object) in order to be able to mock the specific method getTimeSeries() but not the others.
MainClass mainObject = Mockito.spy(new MainClass());
Mockito.when(mainObject.getTimeSeries()).thenReturn(stockTimeSeries);
Then, the method call stockTimeSeries.daily() will get actually mocked by your existing code :
when(stockTimeSeries.daily("TSLA", OutputSize.FULL)).thenThrow(new AlphaVantageException("No stock data available"));
NOTE: you should also consider using .anyString() style methods provided by Mockito API while mocking.

Mocking class is returning null instead of data

In my Junit test, I'm doing the following in my Junit test :
#Before
public void setUp() throws Exception {
reportQueryParams = ReportQueryParams.builder()
.id("07")
.build();
}
#Test
public void tabSerializerTest() {
MetricsSerializer mockMonth = mock(MetricsSerializer.class);
when(mockMonth.getCurrentMonth()).thenReturn("July");
String tabSeparated = mockMonth.serializeMetrics(reportQueryParams);
String expected = new StringBuilder().append("074")
.append("\t")
.append("July")
.toString();
assertEquals(expected, tabSeparated);
}
The function which I am testing:
public String serializeMetrics(final ReportQueryParams reportQueryParams) {
stringJoiner = new StringJoiner("\t");
addValueFromString(reportQueryParams.getId());
addValueFromString(getCurrentMonth());
return stringJoiner.toString();
}
public String getCurrentMonth() {
DateFormat monthFormat = new SimpleDateFormat("MMMMM");
return monthFormat.format(new Date());
}
private void addValueFromString(final String value) {
stringJoiner.add(value);
}
My ReportQueryParams class:
public class ReportQueryParams {
private String id;
}
I am getting "null" in the actual data returned and hence the test is failing. How can I fix this?

Don't mock the object you test.What you have written is "create a mock object that returns July for current month". But this mock object doesn't have real behaviour and the other methods return null.
When you test a class you mock the objects required by the class (in order to insulate behaviour) and not the actual class. Here you can create a new MetricsSerializer (by using new :) and call it's method serializeMethod and compare against the current date (instead of July).
The way you have written the class might not be the best testable way though ;)

Your problem is that you are mocking the class, then testing the mock object, rather than testing a "real" object. I can think of two possible solutions.
Use a Mockito Spy instead of a mock. This is like a mock, but it's a real object, and the methods all have their normal behaviour, instead of "no behaviour" by default. You can stub the getCurrentMonth method of your spy, to make it return what you want.
Since the real cause of your problem is the call to new Date(), you could use a time helper, instead of calling new Date() directly in your getCurrentMonth() method. I have described this technique in detail in my answer to this question

Constructor not defined during Test

I am having a pesky error testing this piece of code.Not sure what I am doing wrong. I have tested standard controllers before but not the getSelectedMethod
Error:
Constructor not defined:[myClass].(ApexPages.StandardController)
public class MyClass{
public List<Web__c> postings {get;set;}
public static final String POSTINGSTATUS = 'Yes';
public MyClass (ApexPages.StandardSetController controller) {
List<Web__c> selectedWeb = (List<Web__c>) controller.getSelected();
postings = [Select Id, Name,
FROM Web___c Where Id IN: selectedWeb
AND Date__c != null
AND Date__c > today];
}
}
My Test Class
private class myTestClass {
static testMethod void WebTest() {
List <Web__c> posting = helper.createWeb(4);
insert posting;
Test.startTest();
PageReference pageRef = Page.VFPAGE;
Test.setCurrentPage(pageRef);
ApexPages.StandardController sc = new ApexPages.standardController(posting[0]);
myClass JPC = new myClass(sc);
sc.setSelected(posting);
Test.stopTest();
}

new ApexPages.standardController(posting[0]) looks wrong to me.
It should likely be new ApexPages.StandardSetController(posting[0]) if you want to create a new instance of ApexPages.StandardSetController, or just ApexPages.standardController(posting[0]) (without the new) if it's a static method that returns such an instance.
BTW: you should state what error you get and where in the code it occurs when asking such a question, as figuring it out without that information is pretty hard. I just found this by chance, I'd asked for that information otherwise.

Mocking member variables of a class using Mockito

I am a newbie to development and to unit tests in particular .
I guess my requirement is pretty simple, but I am keen to know others thoughts on this.
Suppose I have two classes like so -
public class First {
Second second ;
public First(){
second = new Second();
}
public String doSecond(){
return second.doSecond();
}
}
class Second {
public String doSecond(){
return "Do Something";
}
}
Let's say I am writing unit test to test First.doSecond() method. However, suppose, i want to Mock Second.doSecond() class like so. I am using Mockito to do this.
public void testFirst(){
Second sec = mock(Second.class);
when(sec.doSecond()).thenReturn("Stubbed Second");
First first = new First();
assertEquals("Stubbed Second", first.doSecond());
}
I am seeing that the mocking does not take effect and the assertion fails.
Is there no way to mock the member variables of a class that I want to test . ?

You need to provide a way of accessing the member variables so you can pass in a mock (the most common ways would be a setter method or a constructor which takes a parameter).
If your code doesn't provide a way of doing this, it's incorrectly factored for TDD (Test Driven Development).

This is not possible if you can't change your code. But I like dependency injection and Mockito supports it:
public class First {
#Resource
Second second;
public First() {
second = new Second();
}
public String doSecond() {
return second.doSecond();
}
}
Your test:
#RunWith(MockitoJUnitRunner.class)
public class YourTest {
#Mock
Second second;
#InjectMocks
First first = new First();
public void testFirst(){
when(second.doSecond()).thenReturn("Stubbed Second");
assertEquals("Stubbed Second", first.doSecond());
}
}
This is very nice and easy.

If you look closely at your code you'll see that the second property in your test is still an instance of Second, not a mock (you don't pass the mock to first in your code).
The simplest way would be to create a setter for second in First class and pass it the mock explicitly.
Like this:
public class First {
Second second ;
public First(){
second = new Second();
}
public String doSecond(){
return second.doSecond();
}
public void setSecond(Second second) {
this.second = second;
}
}
class Second {
public String doSecond(){
return "Do Something";
}
}
....
public void testFirst(){
Second sec = mock(Second.class);
when(sec.doSecond()).thenReturn("Stubbed Second");
First first = new First();
first.setSecond(sec)
assertEquals("Stubbed Second", first.doSecond());
}
Another would be to pass a Second instance as First's constructor parameter.
If you can't modify the code, I think the only option would be to use reflection:
public void testFirst(){
Second sec = mock(Second.class);
when(sec.doSecond()).thenReturn("Stubbed Second");
First first = new First();
Field privateField = PrivateObject.class.
getDeclaredField("second");
privateField.setAccessible(true);
privateField.set(first, sec);
assertEquals("Stubbed Second", first.doSecond());
}
But you probably can, as it's rare to do tests on code you don't control (although one can imagine a scenario where you have to test an external library cause it's author didn't :))

You can mock member variables of a Mockito Mock with ReflectionTestUtils
ReflectionTestUtils.setField(yourMock, "memberFieldName", value);

If you can't change the member variable, then the other way around this is to use powerMockit and call
Second second = mock(Second.class)
when(second.doSecond()).thenReturn("Stubbed Second");
whenNew(Second.class).withAnyArguments.thenReturn(second);
Now the problem is that ANY call to new Second will return the same mocked instance. But in your simple case this will work.

I had the same issue where a private value was not set because Mockito does not call super constructors. Here is how I augment mocking with reflection.
First, I created a TestUtils class that contains many helpful utils including these reflection methods. Reflection access is a bit wonky to implement each time. I created these methods to test code on projects that, for one reason or another, had no mocking package and I was not invited to include it.
public class TestUtils {
// get a static class value
public static Object reflectValue(Class<?> classToReflect, String fieldNameValueToFetch) {
try {
Field reflectField = reflectField(classToReflect, fieldNameValueToFetch);
reflectField.setAccessible(true);
Object reflectValue = reflectField.get(classToReflect);
return reflectValue;
} catch (Exception e) {
fail("Failed to reflect "+fieldNameValueToFetch);
}
return null;
}
// get an instance value
public static Object reflectValue(Object objToReflect, String fieldNameValueToFetch) {
try {
Field reflectField = reflectField(objToReflect.getClass(), fieldNameValueToFetch);
Object reflectValue = reflectField.get(objToReflect);
return reflectValue;
} catch (Exception e) {
fail("Failed to reflect "+fieldNameValueToFetch);
}
return null;
}
// find a field in the class tree
public static Field reflectField(Class<?> classToReflect, String fieldNameValueToFetch) {
try {
Field reflectField = null;
Class<?> classForReflect = classToReflect;
do {
try {
reflectField = classForReflect.getDeclaredField(fieldNameValueToFetch);
} catch (NoSuchFieldException e) {
classForReflect = classForReflect.getSuperclass();
}
} while (reflectField==null || classForReflect==null);
reflectField.setAccessible(true);
return reflectField;
} catch (Exception e) {
fail("Failed to reflect "+fieldNameValueToFetch +" from "+ classToReflect);
}
return null;
}
// set a value with no setter
public static void refectSetValue(Object objToReflect, String fieldNameToSet, Object valueToSet) {
try {
Field reflectField = reflectField(objToReflect.getClass(), fieldNameToSet);
reflectField.set(objToReflect, valueToSet);
} catch (Exception e) {
fail("Failed to reflectively set "+ fieldNameToSet +"="+ valueToSet);
}
}
}
Then I can test the class with a private variable like this. This is useful for mocking deep in class trees that you have no control as well.
#Test
public void testWithRectiveMock() throws Exception {
// mock the base class using Mockito
ClassToMock mock = Mockito.mock(ClassToMock.class);
TestUtils.refectSetValue(mock, "privateVariable", "newValue");
// and this does not prevent normal mocking
Mockito.when(mock.somthingElse()).thenReturn("anotherThing");
// ... then do your asserts
}
I modified my code from my actual project here, in page. There could be a compile issue or two. I think you get the general idea. Feel free to grab the code and use it if you find it useful.

If you want an alternative to ReflectionTestUtils from Spring in mockito, use
Whitebox.setInternalState(first, "second", sec);

Lots of others have already advised you to rethink your code to make it more testable - good advice and usually simpler than what I'm about to suggest.
If you can't change the code to make it more testable, PowerMock: https://code.google.com/p/powermock/
PowerMock extends Mockito (so you don't have to learn a new mock framework), providing additional functionality. This includes the ability to have a constructor return a mock. Powerful, but a little complicated - so use it judiciously.
You use a different Mock runner. And you need to prepare the class that is going to invoke the constructor. (Note that this is a common gotcha - prepare the class that calls the constructor, not the constructed class)
#RunWith(PowerMockRunner.class)
#PrepareForTest({First.class})
Then in your test set-up, you can use the whenNew method to have the constructor return a mock
whenNew(Second.class).withAnyArguments().thenReturn(mock(Second.class));

Yes, this can be done, as the following test shows (written with the JMockit mocking API, which I develop):
#Test
public void testFirst(#Mocked final Second sec) {
new NonStrictExpectations() {{ sec.doSecond(); result = "Stubbed Second"; }};
First first = new First();
assertEquals("Stubbed Second", first.doSecond());
}
With Mockito, however, such a test cannot be written. This is due to the way mocking is implemented in Mockito, where a subclass of the class to be mocked is created; only instances of this "mock" subclass can have mocked behavior, so you need to have the tested code use them instead of any other instance.

Refactor procedural method using OO principles

I have a method where I want to factor out some code into its own method
This is what I have:
public class TD0301AssignmentForm extends Form {
public TD0301AssignmentForm(TD0301AssignmentDAO dao, STKUser authenticatedUser) {
this.dao = dao;
this.authenticatedUser = authenticatedUser;
}
public Object insert(HttpServletRequest request) {
TD0301Assignment tdas = new TD0301Assignment();
TD0301Assignment tdas_orig = null;
Date dateNow = new Date();
try {
// Get the inuput from HTML form
tdas.setCalc_num(FormUtil.getFieldValue(request, FIELD_CALC_NUM));
processDate(request, tdas);
tdas.setCalc_dept(FormUtil.getFieldValue(request, FIELD_CALC_DEPT));
tdas.setYear_oi(Integer.toString(DateUtil.getIntYear(dateNow)));
processCalcSafetyRequirements(request, tdas);
...etc...
if (isSucces()) {
// Instantiate a base work flow instance!
WorkflowInstance wfi = new WorkflowInstance();
WorkflowInstanceDAO wfiDAO = new WorkflowInstanceDAO();
wfi.setWorkflow_class_id(tdas.getCalc_level());
wfi.setStarted_by(authenticatedUser.getBadge());
wfi.setStatus("0");
wfi.setLast_date(dateNow);
// Insert the WorkFlowInstance into the database, db sets returned sequence number into the wfi object.
wfiDAO.insert(wfi, authenticatedUser);
// Insert the TD0301Assignment into the db
tdas.setWorkflow_instance_id(wfi.getWorkflow_instance_id());
}
I'd like to remove the WorkflowInstance code out into its own method (still in this Class) like this:
if (isSucces()) {
insertWorkFlowInstance(request, tdas);
tdas.setWorkflow_instance_id(wfi.getWorkflow_instance_id());
but wfi is now marked by Eclipse as not available. Should I do something like this to fix the error so that I can still get the wfi.getWorkflow_instance_id() in the isSuccess block above? I know it removes the error, but I am trying to apply best practices.
public class TD0301AssignmentForm extends Form {
private WorkflowInstance wfi = new WorkflowInstance();
private WorkflowInstanceDAO wfiDAO = new WorkflowInstanceDAO();

Instance variables ("properties" or "fields") are not necessarily the way to go if they're not used throughout the entire class.
Variables should have the smallest scope possible--this makes code easier to reason about.
With some noise elided, and also guessing, it seems like the WorkflowInstance and WorkflowInstanceDao could be localized (names changed to match Java conventions):
public class TD0301AssignmentForm extends Form {
public Object insert(HttpServletRequest request) {
TD0301Assignment tdas = new TD0301Assignment();
try {
tdas.setCalcNum(FormUtil.getFieldValue(request, FIELD_CALC_NUM));
processDate(request, tdas);
tdas.setCalcDept(FormUtil.getFieldValue(request, FIELD_CALC_DEPT));
tdas.setYearOi(Integer.toString(DateUtil.getIntYear(dateNow)));
processCalcSafetyRequirements(request, tdas);
if (isSuccess()) {
WorkflowInstance wf = buildWorkflow(tdas);
tdas.setWorkflowInstanceId(wf.getId());
}
}
}
private buildWorkflow(TD0301Assignment tdas) {
WorkflowInstance wfi = new WorkflowInstance();
wfi.setWorkflowClassId(tdas.getCalcLevel());
wfi.setStartedBy(authenticatedUser.getBadge());
wfi.setStatus("0");
wfi.setLastDate(new Date());
WorkflowInstanceDao wfiDao = new WorkflowInstanceDao();
wfiDao.insert(wfi, authenticatedUser);
}
}
Whether or not this is appropriate depends on how/if the WorkflowInstance is used in the rest of the method snippet you show. The DAO is almost certainly able to be localized.
As methods become smaller and easier to think about, they become more testable.
For example, buildWorkflow is almost easy to test, except that the DAO is instantiated "manually". This means that testing the method will either (a) depend on having a working DAO layer, or (b) it must be mocked by a framework that can mock static utility methods (several can).

Without seeing all your code it's not easy to see exactlywhat you are trying to achieve. The reason eclipse is complaining is because it no longer has a wfi instance to play with because you've moved its local instance into your method, but creating another wfi instance is not likely to be your answer.
To get this working change the wfi to be class local and either use it's id directly or return wfi.getWorkflow_instance_id() from insertWorkFlowInstance() and then pass that value into tdas.setWorkflow_instance_id()