Java Mockito - How Mock private member that initializing in the constructor

Question

I tried to mock a member that has collect function to return a Mock object instead of getting to the function itself. But, It getting into the function no matter how i tried to mock the private member.

public class BasicReportManager implements ReportManager {
    private final ReportCollector reportCollector;

    public BasicReportManager(String id) {
        this.reportCollector = new ReportCollector(id);
    }

    private void processReport(ReportType reportTypeToProcess) {
        switch (reportTypeToProcess) {
            case REPORT1:
                Sendable collect = reportCollector.collect();
        }
    }
}

The Test code -

ReportCollector reportData = Mockito.mock(ReportCollector.class);
Sendable sendable = Mockito.mock(Sendable.class);
Mockito.when(reportData.collect()).thenReturn(sendable);

But, When I call the processReport() the collect function occurs. How can I fix it?

BasicReportManager Test Building -

basicReportManager = new BasicReportManager("1");

Thank you.

We need to see (a) how your test creates an instance of BasicReportManager and (b) the implementation of reportCollector() within BasicReportManager. — glytching
– glytching, Commented Sep 13, 2017 at 15:30
I just edit the question with the created instance of BasicReportManager on the Test and Fix the copy-paste problem with the reportCollector(). I should be the reportCollector member. Thanks. — Nofar103
– Nofar103, Commented Sep 13, 2017 at 15:38

glytching · Accepted Answer · 2017-09-13 15:42:08Z

2

If you want to mock the instance of ReportCollector which is used by BasicReportManager then you must inject it when your test case creates BasicReportManager. For example:

ReportCollector reportData = Mockito.mock(ReportCollector.class);
Sendable sendable = Mockito.mock(Sendable.class);
Mockito.when(reportData.collect()).thenReturn(sendable);

BasicReportManager basicReportManager = new BasicReportManager("1", reportData);

// now your test invocation on BasicReportManager will use the mocked instance of ReportCollector

You could consider al alternative like providing a factory for ReportCollector but this simple fact remains: in order to let BasicReportManager use a mocked instance of ReportCollector in your test case you have to be able (somehow!) to provide BasicReportManager with that mocked instance.

answered Sep 13, 2017 at 15:42

glytching

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Juan Cruz Soler · Accepted Answer · 2017-09-13 15:41:27Z

1

You are mocking a ReportCollector object but you never use it inside BasicReportManager.
You should change the BasicReportManager constructor:

public BasicReportManager(ReportCollector reportCollector) {
    this.reportCollector = reportCollector;
}

Then you can do:

ReportCollector reportData = Mockito.mock(ReportCollector.class);
Sendable sendable = Mockito.mock(Sendable.class);
Mockito.when(reportData.collect()).thenReturn(sendable);

basicReportManager = new BasicReportManager(reportData);

answered Sep 13, 2017 at 15:41

Juan Cruz Soler

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