What is Mocking?
Mocking is a way to test the functionality of a class in isolation. Mocking does not require a database connection or properties file read or file server read to test a functionality. Mock objects do the mocking of the real service. A mock object returns a dummy data corresponding to some dummy input passed to it.
Mockito
Mockito facilitates creating mock objects seamlessly. It uses Java Reflection in order to create mock objects for a given interface. Mock objects are nothing but proxy for actual implementations.
Consider a case of Stock Service which returns the price details of a stock. During development, the actual stock service cannot be used to get real-time data. So we need a dummy implementation of the stock service. Mockito can do the same very easily, as its name suggests.
Benefits of Mockito
- No Handwriting − No need to write mock objects on your own.
- Refactoring Safe − Renaming interface method names or reordering parameters will not break the test code as Mocks are created at runtime.
- Return value support − Supports return values.
- Exception support − Supports exceptions.
- Order check support − Supports check on order of method calls.
- Annotation support − Supports creating mocks using annotation.
Consider the following code snippet.
package com.tutorialspoint.mock; import java.util.ArrayList; import java.util.List; import static org.mockito.Mockito.*; public class PortfolioTester { public static void main(String[] args){ //Create a portfolio object which is to be tested Portfolio portfolio = new Portfolio(); //Creates a list of stocks to be added to the portfolio List<Stock> stocks = new ArrayList<Stock>(); Stock googleStock = new Stock("1","Google", 10); Stock microsoftStock = new Stock("2","Microsoft",100); stocks.add(googleStock); stocks.add(microsoftStock); //Create the mock object of stock service StockService stockServiceMock = mock(StockService.class); // mock the behavior of stock service to return the value of various stocks when(stockServiceMock.getPrice(googleStock)).thenReturn(50.00); when(stockServiceMock.getPrice(microsoftStock)).thenReturn(1000.00); //add stocks to the portfolio portfolio.setStocks(stocks); //set the stockService to the portfolio portfolio.setStockService(stockServiceMock); double marketValue = portfolio.getMarketValue(); //verify the market value to be //10*50.00 + 100* 1000.00 = 500.00 + 100000.00 = 100500 System.out.println("Market value of the portfolio: "+ marketValue); } }
Let's understand the important concepts of the above program. The complete code is available in the chapter First Application.
- Portfolio − An object to carry a list of stocks and to get the market value computed using stock prices and stock quantity.
- Stock − An object to carry the details of a stock such as its id, name, quantity, etc.
- StockService − A stock service returns the current price of a stock.
- mock(...) − Mockito created a mock of stock service.
- when(...).thenReturn(...) − Mock implementation of getPrice method of stockService interface. For googleStock, return 50.00 as price.
- portfolio.setStocks(...) − The portfolio now contains a list of two stocks.
- portfolio.setStockService(...) − Assigns the stockService Mock object to the portfolio.
- portfolio.getMarketValue() − The portfolio returns the market value based on its stocks using the mock stock service.
Mockito - Environment Setup
Mockito is a framework for Java, so the very first requirement is to have JDK installed in your machine.
System Requirement
JDK | 1.5 or above. |
---|---|
Memory | no minimum requirement. |
Disk Space | no minimum requirement. |
Operating System | no minimum requirement. |
Step 1 − Verify Java Installation on Your Machine
Open the console and execute the following java command.
OS | Task | Command |
---|---|---|
Windows | Open Command Console | c:\> java -version |
Linux | Open Command Terminal | $ java -version |
Mac | Open Terminal | machine:> joseph$ java -version |
Let's verify the output for all the operating systems −
OS | Output |
---|---|
Windows |
java version "1.6.0_21"
Java(TM) SE Runtime Environment (build 1.6.0_21-b07)
Java HotSpot(TM) Client VM (build 17.0-b17, mixed mode, sharing)
|
Linux |
java version "1.6.0_21"
Java(TM) SE Runtime Environment (build 1.6.0_21-b07)
Java HotSpot(TM) Client VM (build 17.0-b17, mixed mode, sharing)
|
Mac |
java version "1.6.0_21"
Java(TM) SE Runtime Environment (build 1.6.0_21-b07)
Java HotSpot(TM)64-Bit Server VM (build 17.0-b17, mixed mode, sharing)
|
If you do not have Java installed, To install the Java Software Development Kit (SDK) click here.
We assume you have Java 1.6.0_21 installed on your system for this tutorial.
Step 2 − Set JAVA Environment
Set the JAVA_HOME environment variable to point to the base directory location where Java is installed on your machine. For example,
OS | Output |
---|---|
Windows | Set the environment variable JAVA_HOME to C:\Program Files\Java\jdk1.6.0_21 |
Linux | export JAVA_HOME=/usr/local/java-current |
Mac | export JAVA_HOME=/Library/Java/Home |
Append the location of the Java compiler to your System Path.
OS | Output |
---|---|
Windows | Append the string ;C:\Program Files\Java\jdk1.6.0_21\bin to the end of the system variable, Path. |
Linux | export PATH=$PATH:$JAVA_HOME/bin/ |
Mac | not required |
Verify Java Installation using the command java -version as explained above.
Step 3 − Download Mockito-All Archive
To download the latest version of Mockito from Maven Repository click here.
Save the jar file on your C drive, let's say, C:\>Mockito.
OS | Archive name |
---|---|
Windows | mockito-all-2.0.2-beta.jar |
Linux | mockito-all-2.0.2-beta.jar |
Mac | mockito-all-2.0.2-beta.jar |
Step 4 − Set Mockito Environment
Set the Mockito_HOME environment variable to point to the base directory location where Mockito and dependency jars are stored on your machine. The following table shows how to set the environment variable on different operating systems, assuming we've extracted mockito-all-2.0.2-beta.jar onto C:\>Mockito folder.
OS | Output |
---|---|
Windows | Set the environment variable Mockito_HOME to C:\Mockito |
Linux | export Mockito_HOME=/usr/local/Mockito |
Mac | export Mockito_HOME=/Library/Mockito |
Step 5 − Set CLASSPATH Variable
Set the CLASSPATH environment variable to point to the location where Mockito jar is stored. The following table shows how to set the CLASSPATH variable on different operating systems.
OS | Output |
---|---|
Windows | Set the environment variable CLASSPATH to %CLASSPATH%;%Mockito_HOME%\mockito-all-2.0.2-beta.jar;.; |
Linux | export CLASSPATH=$CLASSPATH:$Mockito_HOME/mockito-all-2.0.2-beta.jar:. |
Mac | export CLASSPATH=$CLASSPATH:$Mockito_HOME/mockito-all-2.0.2-beta.jar:. |
Step 6 − Download JUnit Archive
Download the latest version of JUnit jar file from Github. Save the folder at the location C:\>Junit.
OS | Archive name |
---|---|
Windows | junit4.11.jar, hamcrest-core-1.2.1.jar |
Linux | junit4.11.jar, hamcrest-core-1.2.1.jar |
Mac | junit4.11.jar, hamcrest-core-1.2.1.jar |
Step 7 − Set JUnit Environment
Set the JUNIT_HOME environment variable to point to the base directory location where JUnit jars are stored on your machine. The following table shows how to set this environment variable on different operating systems, assuming we've stored junit4.11.jar and hamcrest-core-1.2.1.jar at C:\>Junit.
OS | Output |
---|---|
Windows | Set the environment variable JUNIT_HOME to C:\JUNIT |
Linux | export JUNIT_HOME=/usr/local/JUNIT |
Mac | export JUNIT_HOME=/Library/JUNIT |
Step 8 − Set CLASSPATH Variable
Set the CLASSPATH environment variable to point to the JUNIT jar location. The following table shows how it is done on different operating systems.
OS | Output |
---|---|
Windows | Set the environment variable CLASSPATH to %CLASSPATH%;%JUNIT_HOME%\junit4.11.jar;%JUNIT_HOME%\hamcrest-core-1.2.1.jar;.; |
Linux | export CLASSPATH=$CLASSPATH:$JUNIT_HOME/junit4.11.jar:$JUNIT_HOME/hamcrest-core-1.2.1.jar:. |
Mac | export CLASSPATH=$CLASSPATH:$JUNIT_HOME/junit4.11.jar:$JUNIT_HOME/hamcrest-core-1.2.1.jar:. |
Mockito - First Application
Before going into the details of the Mockito Framework, let's see an application in action. In this example, we've created a mock of Stock Service to get the dummy price of some stocks and unit tested a java class named Portfolio.
The process is discussed below in a step-by-step manner.
Step 1 − Create a JAVA class to represent the Stock
File: Stock.java
public class Stock { private String stockId; private String name; private int quantity; public Stock(String stockId, String name, int quantity){ this.stockId = stockId; this.name = name; this.quantity = quantity; } public String getStockId() { return stockId; } public void setStockId(String stockId) { this.stockId = stockId; } public int getQuantity() { return quantity; } public String getTicker() { return name; } }
Step 2 − Create an interface StockService to get the price of a stock
File: StockService.java
public interface StockService { public double getPrice(Stock stock); }
Step 3 − Create a class Portfolio to represent the portfolio of any client
File: Portfolio.java
import java.util.List; public class Portfolio { private StockService stockService; private List<Stock> stocks; public StockService getStockService() { return stockService; } public void setStockService(StockService stockService) { this.stockService = stockService; } public List<Stock> getStocks() { return stocks; } public void setStocks(List<Stock> stocks) { this.stocks = stocks; } public double getMarketValue(){ double marketValue = 0.0; for(Stock stock:stocks){ marketValue += stockService.getPrice(stock) * stock.getQuantity(); } return marketValue; } }
Step 4 − Test the Portfolio class
Let's test the Portfolio class, by injecting in it a mock of stockservice. Mock will be created by Mockito.
File: PortfolioTester.java
package com.tutorialspoint.mock; import java.util.ArrayList; import java.util.List; import static org.mockito.Mockito.*; public class PortfolioTester { Portfolio portfolio; StockService stockService; public static void main(String[] args){ PortfolioTester tester = new PortfolioTester(); tester.setUp(); System.out.println(tester.testMarketValue()?"pass":"fail"); } public void setUp(){ //Create a portfolio object which is to be tested portfolio = new Portfolio(); //Create the mock object of stock service stockService = mock(StockService.class); //set the stockService to the portfolio portfolio.setStockService(stockService); } public boolean testMarketValue(){ //Creates a list of stocks to be added to the portfolio List<Stock> stocks = new ArrayList<Stock>(); Stock googleStock = new Stock("1","Google", 10); Stock microsoftStock = new Stock("2","Microsoft",100); stocks.add(googleStock); stocks.add(microsoftStock); //add stocks to the portfolio portfolio.setStocks(stocks); //mock the behavior of stock service to return the value of various stocks when(stockService.getPrice(googleStock)).thenReturn(50.00); when(stockService.getPrice(microsoftStock)).thenReturn(1000.00); double marketValue = portfolio.getMarketValue(); return marketValue == 100500.0; } }
Step 5 − Verify the result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac Stock.java StockService.java Portfolio.java PortfolioTester.java
Now run the PortfolioTester to see the result −
C:\Mockito_WORKSPACE>java PortfolioTester
Verify the Output
pass
Mockito - JUnit Integration
In this chapter, we'll learn how to integrate JUnit and Mockito together. Here we will create a Math Application which uses CalculatorService to perform basic mathematical operations such as addition, subtraction, multiply, and division.
We'll use Mockito to mock the dummy implementation of CalculatorService. In addition, we've made extensive use of annotations to showcase their compatibility with both JUnit and Mockito.
The process is discussed below in a step-by-step manner.
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
File: MathApplicationTester.java
import static org.mockito.Mockito.when; import org.junit.Assert; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.InjectMocks; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { //@InjectMocks annotation is used to create and inject the mock object @InjectMocks MathApplication mathApplication = new MathApplication(); //@Mock annotation is used to create the mock object to be injected @Mock CalculatorService calcService; @Test public void testAdd(){ //add the behavior of calc service to add two numbers when(calcService.add(10.0,20.0)).thenReturn(30.00); //test the add functionality Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); } }
Step 4 − Create a class to execute to test cases
Create a java class file named TestRunner in C> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
true
To learn more about JUnit, please refer to JUnit Tutorial at Tutorials Point.
Mockito - Adding Behavior
Mockito adds a functionality to a mock object using the methods when(). Take a look at the following code snippet.
//add the behavior of calc service to add two numbers when(calcService.add(10.0,20.0)).thenReturn(30.00);
Here we've instructed Mockito to give a behavior of adding 10 and 20 to the add method of calcService and as a result, to return the value of 30.00.
At this point of time, Mock recorded the behavior and is a working mock object.
//add the behavior of calc service to add two numbers when(calcService.add(10.0,20.0)).thenReturn(30.00);
Example
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
File: MathApplicationTester.java
import static org.mockito.Mockito.when; import org.junit.Assert; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.InjectMocks; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { //@InjectMocks annotation is used to create and inject the mock object @InjectMocks MathApplication mathApplication = new MathApplication(); //@Mock annotation is used to create the mock object to be injected @Mock CalculatorService calcService; @Test public void testAdd(){ //add the behavior of calc service to add two numbers when(calcService.add(10.0,20.0)).thenReturn(30.00); //test the add functionality Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\>Mockito_WORKSPACE to execute the test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
true
Mockito - Verifying Behavior
Mockito can ensure whether a mock method is being called with reequired arguments or not. It is done using the verify() method. Take a look at the following code snippet.
//test the add functionality Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); //verify call to calcService is made or not with same arguments. verify(calcService).add(10.0, 20.0);
Example - verify() with same arguments
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ //return calcService.add(input1, input2); return input1 + input2; } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
File: MathApplicationTester.java
import static org.mockito.Mockito.verify; import static org.mockito.Mockito.when; import org.junit.Assert; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.InjectMocks; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { //@InjectMocks annotation is used to create and inject the mock object @InjectMocks MathApplication mathApplication = new MathApplication(); //@Mock annotation is used to create the mock object to be injected @Mock CalculatorService calcService; @Test public void testAdd(){ //add the behavior of calc service to add two numbers when(calcService.add(10.0,20.0)).thenReturn(30.00); //test the add functionality Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); //verify the behavior verify(calcService).add(10.0, 20.0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
true
Example - verify() with different arguments
Step 1 − Create an interface CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ //return calcService.add(input1, input2); return input1 + input2; } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
File: MathApplicationTester.java
import static org.mockito.Mockito.verify; import static org.mockito.Mockito.when; import org.junit.Assert; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.InjectMocks; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { //@InjectMocks annotation is used to create and inject the mock object @InjectMocks MathApplication mathApplication = new MathApplication(); //@Mock annotation is used to create the mock object to be injected @Mock CalculatorService calcService; @Test public void testAdd(){ //add the behavior of calc service to add two numbers when(calcService.add(10.0,20.0)).thenReturn(30.00); //test the add functionality Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); //verify the behavior verify(calcService).add(20.0, 30.0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
testAdd(MathApplicationTester): Argument(s) are different! Wanted: calcService.add(20.0, 30.0); -> at MathApplicationTester.testAdd(MathApplicationTester.java:32) Actual invocation has different arguments: calcService.add(10.0, 20.0); -> at MathApplication.add(MathApplication.java:10) false
Mockito - Expecting Calls
Mockito provides a special check on the number of calls that can be made on a particular method. Suppose MathApplication should call the CalculatorService.serviceUsed() method only once, then it should not be able to call CalculatorService.serviceUsed() more than once.
//add the behavior of calc service to add two numbers when(calcService.add(10.0,20.0)).thenReturn(30.00); //limit the method call to 1, no less and no more calls are allowed verify(calcService, times(1)).add(10.0, 20.0);
Create CalculatorService interface as follows.
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Example
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
File: MathApplicationTester.java
import static org.mockito.Mockito.verify; import static org.mockito.Mockito.when; import static org.mockito.Mockito.times; import static org.mockito.Mockito.never; import org.junit.Assert; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.InjectMocks; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { //@InjectMocks annotation is used to create and inject the mock object @InjectMocks MathApplication mathApplication = new MathApplication(); //@Mock annotation is used to create the mock object to be injected @Mock CalculatorService calcService; @Test public void testAdd(){ //add the behavior of calc service to add two numbers when(calcService.add(10.0,20.0)).thenReturn(30.00); //add the behavior of calc service to subtract two numbers when(calcService.subtract(20.0,10.0)).thenReturn(10.00); //test the add functionality Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); //test the subtract functionality Assert.assertEquals(mathApplication.subtract(20.0, 10.0),10.0,0.0); //default call count is 1 verify(calcService).subtract(20.0, 10.0); //check if add function is called three times verify(calcService, times(3)).add(10.0, 20.0); //verify that method was never called on a mock verify(calcService, never()).multiply(10.0,20.0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
true
Mockito - Varying Calls
Mockito provides the following additional methods to vary the expected call counts.
- atLeast (int min) − expects min calls.
- atLeastOnce () − expects at least one call.
- atMost (int max) − expects max calls.
Example
Step 1 − Create an interface CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
File: MathApplicationTester.java
import static org.mockito.Mockito.verify; import static org.mockito.Mockito.when; import static org.mockito.Mockito.atLeastOnce; import static org.mockito.Mockito.atLeast; import static org.mockito.Mockito.atMost; import org.junit.Assert; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.InjectMocks; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { //@InjectMocks annotation is used to create and inject the mock object @InjectMocks MathApplication mathApplication = new MathApplication(); //@Mock annotation is used to create the mock object to be injected @Mock CalculatorService calcService; @Test public void testAdd(){ //add the behavior of calc service to add two numbers when(calcService.add(10.0,20.0)).thenReturn(30.00); //add the behavior of calc service to subtract two numbers when(calcService.subtract(20.0,10.0)).thenReturn(10.00); //test the add functionality Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); //test the subtract functionality Assert.assertEquals(mathApplication.subtract(20.0, 10.0),10.0,0.0); //check a minimum 1 call count verify(calcService, atLeastOnce()).subtract(20.0, 10.0); //check if add function is called minimum 2 times verify(calcService, atLeast(2)).add(10.0, 20.0); //check if add function is called maximum 3 times verify(calcService, atMost(3)).add(10.0,20.0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s)
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
true
Mockito - Exception Handling
Mockito provides the capability to a mock to throw exceptions, so exception handling can be tested. Take a look at the following code snippet.
//add the behavior to throw exception doThrow(new Runtime Exception("divide operation not implemented")) .when(calcService).add(10.0,20.0);
Here we've added an exception clause to a mock object. MathApplication makes use of calcService using its add method and the mock throws a RuntimeException whenever calcService.add() method is invoked.
Example
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
File: MathApplicationTester.java
import static org.mockito.Mockito.doThrow; import org.junit.Assert; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.InjectMocks; import org.mockito.Mock; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoRunner.class) public class MathApplicationTester { // @TestSubject annotation is used to identify class which is going to use the mock object @TestSubject MathApplication mathApplication = new MathApplication(); //@Mock annotation is used to create the mock object to be injected @Mock CalculatorService calcService; @Test(expected = RuntimeException.class) public void testAdd(){ //add the behavior to throw exception doThrow(new RuntimeException("Add operation not implemented")) .when(calcService).add(10.0,20.0); //test the add functionality Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
testAdd(MathApplicationTester): Add operation not implemented false
Mockito - Create Mock
So far, we've used annotations to create mocks. Mockito provides various methods to create mock objects. mock() creates mocks without bothering about the order of method calls that the mock is going to make in due course of its action.
Syntax
calcService = mock(CalculatorService.class);
Example
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
Here we've added two mock method calls, add() and subtract(), to the mock object via when(). However during testing, we've called subtract() before calling add(). When we create a mock object using create(), the order of execution of the method does not matter.
File: MathApplicationTester.java
package com.tutorialspoint.mock; import static org.mockito.Mockito.mock; import static org.mockito.Mockito.verify; import static org.mockito.Mockito.when; import org.junit.Assert; import org.junit.Before; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { private MathApplication mathApplication; private CalculatorService calcService; @Before public void setUp(){ mathApplication = new MathApplication(); calcService = mock(CalculatorService.class); mathApplication.setCalculatorService(calcService); } @Test public void testAddAndSubtract(){ //add the behavior to add numbers when(calcService.add(20.0,10.0)).thenReturn(30.0); //subtract the behavior to subtract numbers when(calcService.subtract(20.0,10.0)).thenReturn(10.0); //test the subtract functionality Assert.assertEquals(mathApplication.subtract(20.0, 10.0),10.0,0); //test the add functionality Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0); //verify call to calcService is made or not verify(calcService).add(20.0,10.0); verify(calcService).subtract(20.0,10.0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
true
Mockito - Ordered Verification
Mockito provides Inorder class which takes care of the order of method calls that the mock is going to make in due course of its action.
Syntax
//create an inOrder verifier for a single mock InOrder inOrder = inOrder(calcService); //following will make sure that add is first called then subtract is called. inOrder.verify(calcService).add(20.0,10.0); inOrder.verify(calcService).subtract(20.0,10.0);
Example
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
Here we've added two mock method calls, add() and subtract(), to the mock object via when(). However during testing, we've called subtract() before calling add(). When we create a mock object using Mockito, the order of execution of the method does not matter. Using InOrder class, we can ensure call order.
File: MathApplicationTester.java
import static org.mockito.Mockito.mock; import static org.mockito.Mockito.verify; import static org.mockito.Mockito.when; import static org.mockito.Mockito.inOrder; import org.junit.Assert; import org.junit.Before; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.InOrder; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { private MathApplication mathApplication; private CalculatorService calcService; @Before public void setUp(){ mathApplication = new MathApplication(); calcService = mock(CalculatorService.class); mathApplication.setCalculatorService(calcService); } @Test public void testAddAndSubtract(){ //add the behavior to add numbers when(calcService.add(20.0,10.0)).thenReturn(30.0); //subtract the behavior to subtract numbers when(calcService.subtract(20.0,10.0)).thenReturn(10.0); //test the add functionality Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0); //test the subtract functionality Assert.assertEquals(mathApplication.subtract(20.0, 10.0),10.0,0); //create an inOrder verifier for a single mock InOrder inOrder = inOrder(calcService); //following will make sure that add is first called then subtract is called. inOrder.verify(calcService).subtract(20.0,10.0); inOrder.verify(calcService).add(20.0,10.0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
testAddAndSubtract(MathApplicationTester): Verification in order failure Wanted but not invoked: calculatorService.add(20.0, 10.0); -> at MathApplicationTester.testAddAndSubtract(MathApplicationTester.java:48) Wanted anywhere AFTER following interaction: calculatorService.subtract(20.0, 10.0); -> at MathApplication.subtract(MathApplication.java:13) false
Mockito - Callbacks
Mockito provides a Answer interface which allows stubbing with generic interface.
Syntax
//add the behavior to add numbers when(calcService.add(20.0,10.0)).thenAnswer(new Answer<Double>() { @Override public Double answer(InvocationOnMock invocation) throws Throwable { //get the arguments passed to mock Object[] args = invocation.getArguments(); //get the mock Object mock = invocation.getMock(); //return the result return 30.0; } });
Example
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
Here we've added one mock method calls, add() to the mock object via when(). However during testing, we've called subtract() before calling add(). When we create a mock object using Mockito.createStrictMock(), the order of execution of the method does matter.
File: MathApplicationTester.java
import static org.mockito.Mockito.mock; import static org.mockito.Mockito.verify; import static org.mockito.Mockito.when; import static org.mockito.Mockito.inOrder; import org.junit.Assert; import org.junit.Before; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.InOrder; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { private MathApplication mathApplication; private CalculatorService calcService; @Before public void setUp(){ mathApplication = new MathApplication(); calcService = mock(CalculatorService.class); mathApplication.setCalculatorService(calcService); } @Test public void testAdd(){ //add the behavior to add numbers when(calcService.add(20.0,10.0)).thenAnswer(new Answer<Double>() { @Override public Double answer(InvocationOnMock invocation) throws Throwable { //get the arguments passed to mock Object[] args = invocation.getArguments(); //get the mock Object mock = invocation.getMock(); //return the result return 30.0; } }); //test the add functionality Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
true
Mockito - Spying
Mockito provides option to create spy on real objects. When spy is called, then actual method of real object is called.
Syntax
//create a spy on actual object calcService = spy(calculator); //perform operation on real object //test the add functionality Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0);
Example
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
Here we've added one mock method calls, add() to the mock object via when(). However during testing, we've called subtract() before calling add(). When we create a mock object using Mockito.createStrictMock(), the order of execution of the method does matter.
File: MathApplicationTester.java
import static org.mockito.Mockito.spy; import org.junit.Assert; import org.junit.Before; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { private MathApplication mathApplication; private CalculatorService calcService; @Before public void setUp(){ mathApplication = new MathApplication(); Calculator calculator = new Calculator(); calcService = spy(calculator); mathApplication.setCalculatorService(calcService); } @Test public void testAdd(){ //perform operation on real object //test the add functionality Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0); } class Calculator implements CalculatorService { @Override public double add(double input1, double input2) { return input1 + input2; } @Override public double subtract(double input1, double input2) { throw new UnsupportedOperationException("Method not implemented yet!"); } @Override public double multiply(double input1, double input2) { throw new UnsupportedOperationException("Method not implemented yet!"); } @Override public double divide(double input1, double input2) { throw new UnsupportedOperationException("Method not implemented yet!"); } } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
true
Mockito - Resetting Mock
Mockito provides the capability to a reset a mock so that it can be reused later. Take a look at the following code snippet.
//reset mock reset(calcService);
Here we've reset mock object. MathApplication makes use of calcService and after reset the mock, using mocked method will fail the test.
Example
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
File: MathApplicationTester.java
package com.tutorialspoint.mock; import static org.mockito.Mockito.mock; import static org.mockito.Mockito.when; import static org.mockito.Mockito.reset; import org.junit.Assert; import org.junit.Before; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { private MathApplication mathApplication; private CalculatorService calcService; @Before public void setUp(){ mathApplication = new MathApplication(); calcService = mock(CalculatorService.class); mathApplication.setCalculatorService(calcService); } @Test public void testAddAndSubtract(){ //add the behavior to add numbers when(calcService.add(20.0,10.0)).thenReturn(30.0); //test the add functionality Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0); //reset the mock reset(calcService); //test the add functionality after resetting the mock Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
testAddAndSubtract(MathApplicationTester): expected:<0.0> but was:<30.0> false
Mockito - Behavior Driven Development
Behavior Driven Development is a style of writing tests uses given, when and then format as test methods. Mockito provides special methods to do so. Take a look at the following code snippet.
//Given given(calcService.add(20.0,10.0)).willReturn(30.0); //when double result = calcService.add(20.0,10.0); //then Assert.assertEquals(result,30.0,0);
Here we're using given method of BDDMockito class instead of when method of .
Example
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
File: MathApplicationTester.java
package com.tutorialspoint.mock; import static org.mockito.BDDMockito.*; import org.junit.Assert; import org.junit.Before; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { private MathApplication mathApplication; private CalculatorService calcService; @Before public void setUp(){ mathApplication = new MathApplication(); calcService = mock(CalculatorService.class); mathApplication.setCalculatorService(calcService); } @Test public void testAdd(){ //Given given(calcService.add(20.0,10.0)).willReturn(30.0); //when double result = calcService.add(20.0,10.0); //then Assert.assertEquals(result,30.0,0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
true
Mockito - Timeouts
Mockito provides a special Timeout option to test if a method is called within stipulated time frame.
Syntax
//passes when add() is called within 100 ms. verify(calcService,timeout(100)).add(20.0,10.0);
Example
Step 1 − Create an interface called CalculatorService to provide mathematical functions
File: CalculatorService.java
public interface CalculatorService { public double add(double input1, double input2); public double subtract(double input1, double input2); public double multiply(double input1, double input2); public double divide(double input1, double input2); }
Step 2 − Create a JAVA class to represent MathApplication
File: MathApplication.java
public class MathApplication { private CalculatorService calcService; public void setCalculatorService(CalculatorService calcService){ this.calcService = calcService; } public double add(double input1, double input2){ return calcService.add(input1, input2); } public double subtract(double input1, double input2){ return calcService.subtract(input1, input2); } public double multiply(double input1, double input2){ return calcService.multiply(input1, input2); } public double divide(double input1, double input2){ return calcService.divide(input1, input2); } }
Step 3 − Test the MathApplication class
Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by Mockito.
File: MathApplicationTester.java
package com.tutorialspoint.mock; import static org.mockito.Mockito.mock; import static org.mockito.Mockito.verify; import static org.mockito.Mockito.when; import org.junit.Assert; import org.junit.Before; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.runners.MockitoJUnitRunner; // @RunWith attaches a runner with the test class to initialize the test data @RunWith(MockitoJUnitRunner.class) public class MathApplicationTester { private MathApplication mathApplication; private CalculatorService calcService; @Before public void setUp(){ mathApplication = new MathApplication(); calcService = mock(CalculatorService.class); mathApplication.setCalculatorService(calcService); } @Test public void testAddAndSubtract(){ //add the behavior to add numbers when(calcService.add(20.0,10.0)).thenReturn(30.0); //subtract the behavior to subtract numbers when(calcService.subtract(20.0,10.0)).thenReturn(10.0); //test the subtract functionality Assert.assertEquals(mathApplication.subtract(20.0, 10.0),10.0,0); //test the add functionality Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0); //verify call to add method to be completed within 100 ms verify(calcService, timeout(100)).add(20.0,10.0); //invocation count can be added to ensure multiplication invocations //can be checked within given timeframe verify(calcService, timeout(100).times(1)).subtract(20.0,10.0); } }
Step 4 − Execute test cases
Create a java class file named TestRunner in C:\> Mockito_WORKSPACE to execute Test case(s).
File: TestRunner.java
import org.junit.runner.JUnitCore; import org.junit.runner.Result; import org.junit.runner.notification.Failure; public class TestRunner { public static void main(String[] args) { Result result = JUnitCore.runClasses(MathApplicationTester.class); for (Failure failure : result.getFailures()) { System.out.println(failure.toString()); } System.out.println(result.wasSuccessful()); } }
Step 5 − Verify the Result
Compile the classes using javac compiler as follows −
C:\Mockito_WORKSPACE>javac CalculatorService.java MathApplication. java MathApplicationTester.java TestRunner.java
Now run the Test Runner to see the result −
C:\Mockito_WORKSPACE>java TestRunner
Verify the output.
true
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