Mockito cannot mock into this class

Question

I am trying to test my database project with unit test case with Junit and Mockito. But when i do it i am getting an error.. posting my code and stack trace. I am entirely new to testing . Kindly help

Note * - I am not using any framework

Testing code

patientTest.java

package com.test;

import static org.junit.Assert.*;
import static org.mockito.Mockito.*;
import java.io.*;
import javax.servlet.http.*;
import org.apache.commons.io.FileUtils;
import org.junit.Test;
import org.mockito.Mockito;

import com.consentServlets.SaveServlet;

public class patientTest extends Mockito{

    @Test
    public void testServlet() throws Exception {
        HttpServletRequest request = mock(HttpServletRequest.class);       
        HttpServletResponse response = mock(HttpServletResponse.class);    

        when(request.getParameter("fname")).thenReturn("Rahul");
        when(request.getParameter("lname")).thenReturn("Sen");

        StringWriter stringWriter = new StringWriter();
        PrintWriter writer = new PrintWriter(stringWriter);
        when(response.getWriter()).thenReturn(writer);

        new SaveServlet().doPost(request, response);

        verify(request, atLeast(1)).getParameter("fname"); 
        writer.flush(); // it may not have been flushed yet...
        assertTrue(stringWriter.toString().contains("My expected string"));
    }
}

SaveServlet.java

package com.consentServlets;


import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/SaveServlet")
public class SaveServlet extends HttpServlet {
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out=response.getWriter();
        //Getting the attributes from the UI
        String first_Name = request.getParameter("fname");
        String last_Name = request.getParameter("lname");
        String gender = request.getParameter("gender");
        String age = request.getParameter("age");
        String dob = request.getParameter("dob");

        //Setting the objects to insert the achieved attributes to corresponding the columns of the table
        patient addPatient = new patient();
        addPatient.setLastName(last_Name);
        addPatient.setFirstName(first_Name);
        addPatient.setGender(gender);
        addPatient.setAge(age);
        addPatient.setDoB(dob);

        out.print(" <link rel=\"stylesheet\" href=\"https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.css\">");
        //calling the save function from the patientDao class to execute the query
        int status=patientDao.save(addPatient);
        if(status>0){
            out.print("<p>Patient Record saved successfully!</p>");
            request.getRequestDispatcher("index.html").include(request, response);
        }else{
            out.println("Sorry! unable to save record");
        }

        out.close();
    }

}

PatientDao.java

package com.consentServlets;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List; 

public class patientDao {
    //establishing the connection with the database
    public static Connection getConnection(){  
        Connection con=null;  
        try{  
            Class.forName("com.mysql.jdbc.Driver");
            con=DriverManager.getConnection("jdbc:mysql://localhost:3306/consent_share","root","");
        }catch(Exception e){System.out.println(e);}  
        return con;  
    }  
    public static int save(patient addPatient){  
        int status = 0;  
        //Inserting patient details from UI to Database
        try{                            
            Connection con = patientDao.getConnection();  
            PreparedStatement ps = con.prepareStatement(  
                    "insert into patient(last_name,first_name,gender,age,dob) values (?,?,?,?,?)");  
            ps.setString(1,addPatient.getLastName());  
            ps.setString(2,addPatient.getFirstName());  
            ps.setString(3,addPatient.getGender());  
            ps.setString(4,addPatient.getAge());
            ps.setString(5,addPatient.getDoB());

            status = ps.executeUpdate();  

            con.close();  
        }catch(Exception ex){ex.printStackTrace();}  

        return status;  
    }  

    public static patient getPatientbyId(int id){  
        patient getPatient = new patient();  
        //selecting a patient record by matching the patient_ID 
        try{ 
            Connection con = patientDao.getConnection();  
            PreparedStatement ps = con.prepareStatement("select * from patient where patient_id=?");  
            ps.setInt(1,id);  
            ResultSet rs = ps.executeQuery();  
            if(rs.next()){  
                getPatient.setId(rs.getInt(1));  
                getPatient.setLastName(rs.getString(2));  
                getPatient.setFirstName(rs.getString(3));  
                getPatient.setGender(rs.getString(4));  
                getPatient.setAge(rs.getString(5));
                getPatient.setDoB(rs.getString(6)); 
            }  
            con.close();  
        }catch(Exception ex){ex.printStackTrace();}  

        return getPatient;
    }  
    // Fetching all the records from table
    public static List<patient> getAllPatients(){  
        List<patient> list = new ArrayList<patient>();  

        try{  
            Connection con = patientDao.getConnection();  
            PreparedStatement ps = con.prepareStatement("select * from patient");  
            ResultSet rs = ps.executeQuery();  
            while(rs.next()){  
                patient getAllPatients=new patient();  
                getAllPatients.setId(rs.getInt(1));  
                getAllPatients.setFirstName(rs.getString(3));  
                getAllPatients.setLastName(rs.getString(2));  
                getAllPatients.setGender(rs.getString(4));  
                getAllPatients.setAge(rs.getString(5));
                getAllPatients.setDoB(rs.getString(6));   
                list.add(getAllPatients);  
            }  
            con.close();  
        }catch(Exception e){e.printStackTrace();}  

        return list;  
    }  
}  

Stacktrace

    org.mockito.exceptions.base.MockitoException: 
Mockito cannot mock this class: interface javax.servlet.http.HttpServletRequest.

Mockito can only mock non-private & non-final classes.
If you're not sure why you're getting this error, please report to the mailing list.


Java               : 13
JVM vendor name    : Oracle Corporation
JVM vendor version : 13.0.1+9
JVM name           : Java HotSpot(TM) 64-Bit Server VM
JVM version        : 13.0.1+9
JVM info           : mixed mode, sharing
OS name            : Windows 10
OS version         : 10.0


Underlying exception : java.lang.UnsupportedOperationException: Cannot define class using reflection
    at com.test.patientTest.testServlet(patientTest.java:17)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:567)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:89)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:41)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:541)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:763)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:463)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:209)
Caused by: java.lang.UnsupportedOperationException: Cannot define class using reflection
    at net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection$Dispatcher$Unavailable.defineClass(ClassInjector.java:821)
    at net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection.inject(ClassInjector.java:185)
    at net.bytebuddy.dynamic.loading.ClassLoadingStrategy$Default$InjectionDispatcher.load(ClassLoadingStrategy.java:187)
    at net.bytebuddy.dynamic.TypeResolutionStrategy$Passive.initialize(TypeResolutionStrategy.java:79)
    at net.bytebuddy.dynamic.DynamicType$Default$Unloaded.load(DynamicType.java:4376)
    at org.mockito.internal.creation.bytebuddy.SubclassBytecodeGenerator.mockClass(SubclassBytecodeGenerator.java:94)
    at org.mockito.internal.creation.bytebuddy.TypeCachingBytecodeGenerator$1.call(TypeCachingBytecodeGenerator.java:37)
    at org.mockito.internal.creation.bytebuddy.TypeCachingBytecodeGenerator$1.call(TypeCachingBytecodeGenerator.java:34)
    at net.bytebuddy.TypeCache.findOrInsert(TypeCache.java:138)
    at net.bytebuddy.TypeCache$WithInlineExpunction.findOrInsert(TypeCache.java:346)
    at net.bytebuddy.TypeCache.findOrInsert(TypeCache.java:161)
    at net.bytebuddy.TypeCache$WithInlineExpunction.findOrInsert(TypeCache.java:355)
    at org.mockito.internal.creation.bytebuddy.TypeCachingBytecodeGenerator.mockClass(TypeCachingBytecodeGenerator.java:32)
    at org.mockito.internal.creation.bytebuddy.SubclassByteBuddyMockMaker.createMockType(SubclassByteBuddyMockMaker.java:71)
    at org.mockito.internal.creation.bytebuddy.SubclassByteBuddyMockMaker.createMock(SubclassByteBuddyMockMaker.java:42)
    at org.mockito.internal.creation.bytebuddy.ByteBuddyMockMaker.createMock(ByteBuddyMockMaker.java:25)
    at org.mockito.internal.util.MockUtil.createMock(MockUtil.java:35)
    at org.mockito.internal.MockitoCore.mock(MockitoCore.java:63)
    at org.mockito.Mockito.mock(Mockito.java:1729)
    at org.mockito.Mockito.mock(Mockito.java:1642)
    ... 24 more
Caused by: java.lang.IllegalArgumentException: Unknown Java version: 13
    at net.bytebuddy.ClassFileVersion.ofJavaVersion(ClassFileVersion.java:135)
    at net.bytebuddy.ClassFileVersion$VersionLocator$ForJava9CapableVm.locate(ClassFileVersion.java:337)
    at net.bytebuddy.ClassFileVersion.ofThisVm(ClassFileVersion.java:147)
    at net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection$Dispatcher$CreationAction.run(ClassInjector.java:301)
    at net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection$Dispatcher$CreationAction.run(ClassInjector.java:290)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:312)
    at net.bytebuddy.dynamic.loading.ClassInjector$UsingReflection.<clinit>(ClassInjector.java:70)
    at net.bytebuddy.dynamic.loading.ClassLoadingStrategy$Default$InjectionDispatcher.load(ClassLoadingStrategy.java:184)
    ... 41 more

Answer 1

This is almost certainly due to you using a version of Mockito which does not yet support Java 13 because of this error

Caused by: java.lang.IllegalArgumentException: Unknown Java version: 13

It is worth noting it is not Mockito itself that does not support Java 13 but an underlying library byte-buddy that is used for bytecode manipulation.

Official bytebuddy/Mockito documentation doesn't appear to indicate exactly which version adds Java 13 support but it appears to have been added in bytebuddy 1.9.7

Mockito 3.2.2 updates the byte-buddy dependency to 1.10.5 so this should be sufficient.