Monthly Archives: May 2017

Mock new object creation with PowerMock

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Post summary: How to control what objects are being instantiated when using PowerMock.

This post is part of PowerMock series examples. Code shown in examples bellow is available in GitHub java-samples/junit repository.

Mock new object creation

You might have a method which instantiates some object and works with it. This case could be very tricky to automate because you do not have any control on this newly created object. This is where PowerMock comes to help allowing you to control what object is being created by replacing it with a object you can control.

Code to test

Bellow is a simple method where new object is being created inside a method that has to be unit tested.

public class PowerMockDemo {

	public Point publicMethod() {
		return new Point(11, 11);
	}
}

Unit test

What we want to achieve in the unit test is to control instantiation of new Point object so that it is replaced with an object we have control over. First thing to do is to annotate unit test with @RunWith(PowerMockRunner.class) telling JUnit to use PowerMock runner and with @PrepareForTest(PowerMockDemo.class) telling PowerMock to get inside PowerMockDemo class and prepare it for mocking. Mocking is done with PowerMockito.whenNew(Point.class).withAnyArguments().thenReturn(mockPoint). It tells PowerMock when a new object from class Point is instantiated with whatever arguments to return mockPoint instead. It is possible to return different objects based on different arguments Point is created with withArguments() method. Full code is bellow:

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.mockito.Mockito.mock;

@RunWith(PowerMockRunner.class)
@PrepareForTest(PowerMockDemo.class)
public class PowerMockDemoTest {

	private PowerMockDemo powerMockDemo;

	@Before
	public void setUp() {
		powerMockDemo = new PowerMockDemo();
	}

	@Test
	public void testMockNew() throws Exception {
		Point mockPoint = mock(Point.class);

		PowerMockito.whenNew(Point.class)
			.withAnyArguments().thenReturn(mockPoint);

		Point actualMockPoint = powerMockDemo.publicMethod();

		assertThat(actualMockPoint, is(mockPoint));
	}
}

Conclusion

PowerMock allows you to control want new objects are being created and replacing them with object you have control over.

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Mock private method call with PowerMock

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Post summary: How to mock private method with PowerMock by using spy object.

This post is part of PowerMock series examples. Code shown in examples bellow is available in GitHub java-samples/junit repository.

Mock private method

In some cases you may need to alter the behaviour of private method inside the class you are unit testing. You will need to mock this private method and make it return what needed for particular case. Since this private method is inside your class under test then mocking it is little more specific. You have to use spy object.

Spy object

Spy is a real object which mocking framework has access to. Spied objects are partially mocked objects. Some their methods are real some mocked. I would say use spy object with great caution because you do not really know what is happening underneath and whether are you actually testing your class or mocked version of it.

Code to be tested

Bellow is a simple code that has private method which created new Point object based on given as argument one. This private method is used to demonstrate how private methods can be called in Call private method with PowerMock post. In current example there is also a public method which calls this private method with a Point object.

public class PowerMockDemo {

	public Point callPrivateMethod() {
		return privateMethod(new Point(1, 1));
	}

	private Point privateMethod(Point point) {
		return new Point(point.getX() + 1, point.getY() + 1);
	}
}

Unit test

What we want to achieve in the unit test is to mock private method so that each call to it returns an object we have control over. First thing to do is to annotate unit test with @RunWith(PowerMockRunner.class) telling JUnit to use PowerMock runner and with @PrepareForTest(PowerMockDemo.class) telling PowerMock to get inside PowerMockDemo class and prepare it for mocking. Then a spy object has to be created with PowerMockito.spy(new PowerMockDemo()). Actually this is real PowerMockDemo object, but PowerMock is spying on it. The mocking of the private method is done with following code: PowerMockito.doReturn(mockPoint).when(powerMockDemoSpy, “privateMethod”, anyObject()). When “privateMethod” is called with whatever object then return mockPoint which is actually a mocked object. Full code example is bellow:

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.mockito.Matchers.anyObject;
import static org.mockito.Mockito.mock;

@RunWith(PowerMockRunner.class)
@PrepareForTest(PowerMockDemo.class)
public class PowerMockDemoTest {

	private PowerMockDemo powerMockDemoSpy;

	@Before
	public void setUp() {
		powerMockDemoSpy = PowerMockito.spy(new PowerMockDemo());
	}

	@Test
	public void testMockPrivateMethod() throws Exception {
		Point mockPoint = mock(Point.class);

		PowerMockito.doReturn(mockPoint)
			.when(powerMockDemoSpy, "privateMethod", anyObject());

		Point actualMockPoint = powerMockDemoSpy.callPrivateMethod();

		assertThat(actualMockPoint, is(mockPoint));
	}
}

Conclusion

PowerMock provides a way to mock private methods by using spy objects. Mockito also has spy objects, but they are not so powerful as PowerMock’s. One example is that PowerMock can spy on final objects.

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Call private method with PowerMock

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Post summary: How to invoke private method with PowerMock.

This post is part of PowerMock series examples. Code shown in examples bellow is available in GitHub java-samples/junit repository.

Unit test private method

Mainly public methods are being tested, so it is very rare case where you want to unit test private method. PowerMock provides utilities that can invoke private methods via a reflection and get output which can be tested.

Code to be tested

Bellow is a sample code that shows a class with private method in it. It does nothing else but increasing the X and Y coordinates of given as argument Point.

public class PowerMockDemo {

	private Point privateMethod(Point point) {
		return new Point(point.getX() + 1, point.getY() + 1);
	}
}

Unit test

Assume that this private method has to be unit tested for some reason. In order to do so you have to use PowerMock’s Whitebox.invokeMethod(). You give instance of the object, method name as a String and arguments to call method with. In example bellow argument is new Point(11, 11).

import org.junit.Before;
import org.junit.Test;
import org.powermock.reflect.Whitebox;

import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.MatcherAssert.assertThat;

public class PowerMockDemoTest {

	private PowerMockDemo powerMockDemo;

	@Before
	public void setUp() {
		powerMockDemo = new PowerMockDemo();
	}

	@Test
	public void testCallPrivateMethod() throws Exception {
		Point actual = Whitebox.invokeMethod(powerMockDemo, 
			"privateMethod", new Point(11, 11));

		assertThat(actual.getX(), is(12));
		assertThat(actual.getY(), is(12));
	}
}

Conclusion

PowerMock provides utilities which uses reflection to do certain things, as show in example above to invoke private method.

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Soft assertions that do not fail JUnit test

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Post summary: Code examples how to use assertions that do not fail the unit test immediately.

Code shown in examples bellow is available in GitHub java-samples/jersey1 repository.

Unit vs Functional testing

Unit testing paradigm states that each test exercises particular code behaviour. So in a perfect world one unit test would have one assertion which defines unit test result – either passed or failed. This is why unit testing frameworks provide only asserts which stop further execution of current test method. In functional testing usually one test verifies several conditions. Not debating if this is good or bad. Assume you are doing GUI testing, once you have opened particular page you’d better do as much verification as possible to reduce the risk of bugs. Having this page opened over and over for each single check is not the most efficient way of testing. This is why when you run functional tests you need some kind of assert that indicates whether passed or failed but to let the test continue in no critical issue is present. Those are generally called “soft” asserts.

Soft assertions and JUnit

TestNG provides org.testng.asserts.SoftAssert class for soft asserts as it is more oriented towards functional testing. JUnit is unit testing framework, so it does not provide any soft assertions. In order to create such behaviour additional libraries are needed.

AssertJ

AssertJ is library providing fluent assertions. It is very similar to Hamcrest which comes by default with JUnit. Along with all the asserts AssertJ provides soft assertions with its SoftAssertions class inside org.assertj.core.api package.

Usage

Bellow is a functional test run against Dropwizard stub described in Build a RESTful stub server with Dropwizard post. Important is to instantiate new SoftAssertions object before the test verifications and to call assertAll() method in the end to collect results. Best way to do this is to use JUnit’s @Before and @After annotated methods.

package com.automationrhapsody.jersey1;

import com.automationrhapsody.jersey1.model.Person;
import com.automationrhapsody.jersey1.rules.PersonServiceJerseyClient;

import java.util.List;

import org.assertj.core.api.SoftAssertions;
import org.junit.After;
import org.junit.Before;
import org.junit.ClassRule;
import org.junit.Test;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.core.Is.is;

public class PersonServiceTest {

	@ClassRule
	public static final PersonServiceJerseyClient CLIENT 
		= new PersonServiceJerseyClient();

	private SoftAssertions softAssertions;

	private Person person;

	@Before
	public void setUp() {
		person = new Person();
		person.setId(123);
		person.setFirstName("First Name");
		person.setLastName("Last Name");
		person.setEmail("Email");

		softAssertions = new SoftAssertions();
	}

	@After
	public void tearDown() {
		softAssertions.assertAll();
	}

	@Test
	public void testAllOperations() {
		String saveResult = CLIENT.save(person);
		assertThat(saveResult, is("Added Person with id=123"));

		Person actual = CLIENT.get(person.getId());
		softAssertions
			.assertThat(actual.getId()).isEqualTo(person.getId());
		softAssertions
			.assertThat(actual.getFirstName()).isEqualTo(person.getFirstName());
		softAssertions
			.assertThat(actual.getLastName()).isEqualTo(person.getLastName());
		softAssertions
			.assertThat(actual.getEmail()).isEqualTo(person.getEmail());

		String result = CLIENT.remove();
		assertThat(result, is("Last person remove. Total count: 4"));
	}
}

Conclusion

Soft assertions are needed in case of functional tests being run with JUnit. Since such are not available out of the box because JUnit is targeted for unit tests soft assertions can be used from external libraries such as AssertJ.

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Verify static method was called with PowerMock

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Post summary: How to verify that static method was called during unit test with PowerMock.

This post is part of PowerMock series examples. Code shown in examples bellow is available in GitHub java-samples/junit repository.

In Mock static methods in JUnit with PowerMock example post I have given information about PowerMock and how to mock a static method. In current post I will demonstrate how to verify given static method was called during execution of an unit test.

Example class for unit test

We are going to unit test a class called LocatorService that internally uses static method from utilities class Utils. Method randomDistance(int distance) in Utils is returning random variable, hence it has no predictable behaviour and only way to test it is by mocking it:

public class LocatorService {

	public Point generatePointWithinDistance(Point point, int distance) {
		return new Point(point.getX() + Utils.randomDistance(distance), 
			point.getY() + Utils.randomDistance(distance));
	}
}

And Utils class is:

import java.util.Random;

public final class Utils {

	private static final Random RAND = new Random();

	private Utils() {
		// Utilities class
	}

	public static int randomDistance(int distance) {
		return RAND.nextInt(distance + distance) - distance;
	}
}

Nota bene: it is good code design practice to make utilities classes final and with private constructor.

Verify static method call

This is the full code. Additional details are shown bellow it.

package com.automationrhapsody.junit;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.internal.verification.VerificationModeFactory;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
@PrepareForTest(Utils.class)
public class LocatorServiceTest {

	private LocatorService locatorServiceUnderTest;

	@Before
	public void setUp() {
		PowerMockito.mockStatic(Utils.class);

		locatorServiceUnderTest = new LocatorService();
	}

	@Test
	public void testStaticMethodCall() {
		locatorServiceUnderTest
			.generatePointWithinDistance(new Point(11, 11), 1);
		locatorServiceUnderTest
			.generatePointWithinDistance(new Point(11, 11), 234);

		PowerMockito.verifyStatic(VerificationModeFactory.times(2));
		Utils.randomDistance(1);

		PowerMockito.verifyStatic(VerificationModeFactory.times(2));
		Utils.randomDistance(234);

		PowerMockito.verifyNoMoreInteractions(Utils.class);
	}
}

Explanation

Class containing static method should be prepared for mocking with PowerMockito.mockStatic(Utils.class) code. Then call to static method is done inside locatorServiceUnderTest .generatePointWithinDistance() method. In this test it is intentionally called 2 times with different distance (1 and 234) in order to show the verification which consists of two parts. First part is PowerMockito.verifyStatic(VerificationModeFactory.times(2)) which tells PowerMock to verify static method was called 2 times. Second part is Utils.randomDistance(1) which tells exactly which static method should be verified. Instead of 1 in the brackets you can use anyInt() or anyObject(). 1 is used to make verification explicit. As you can see there is second verification that randomDistance() method was called with 234 as well: PowerMockito.verifyStatic(VerificationModeFactory.times(2)); Utils.randomDistance(234);.

Conclusion

PowerMock provides additional power to Mockito mocking library which is described in Mock JUnit tests with Mockito example post. In current post I have shown how to verify static method was called. It is very specific as verification actually consists of two steps.

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Manage Microsoft Excel files in Java with Apache POI

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Post summary: Code examples how to manage Microsoft Excel documents with Apache POI Java library.

Code examples in current post can be found in GitHub java-samples/apache-poi repository.

Two most important use cases where MS Excel documents are useful in automation testing are:

  • Data driven testing where test data is input from an Excel file
  • Output test results to an Excel file for stakeholders

So far I did not needed to use Excel in my automation. Where data driven testing was needed I either used JUnit data provider (see more in Data driven testing with JUnit parameterized tests and Data driven testing with JUnit and Gradle posts) or feeding data in CSV format and reading them with Apache Commons CSV library. My colleague Petar Yordanov introduced me to Apache POI which is very powerful for Excel and other MS format documents management.

Apache POI

he Apache POI Project’s mission is to create and maintain Java APIs for manipulating various file formats based upon the Office Open XML standards (OOXML) and Microsoft’s OLE 2 Compound Document format (OLE2). In short, you can read and write MS Excel files using Java. In addition, you can read and write MS Word and MS PowerPoint files using Java. Apache POI is your Java Excel solution (for Excel 97-2008). See more on Apache POI home page. Full details on supported POI formats can be found in Apache POI Component Overview. From this page you can navigate to more details how to work with specific type of document. Full details on Excel management can be found on Apache POI Spreadsheet Guide.

Usage

Include in Maven project

In current example I will use the poi-ooxml library which for XML based formats introduced in Microsoft Office 2007.

<dependency>
	<groupId>org.apache.poi</groupId>
	<artifactId>poi-ooxml</artifactId>
	<version>3.16</version>
</dependency>

Creating a Workbook

Excel file is actually a XSSFWorkbook object from org.apache.poi.xssf.usermodel package. Workbook can be created empty or from existing file:

// Create empty workbook
XSSFWorkbook newWorkBook = new XSSFWorkbook();
// Create workbook from existing file
XSSFWorkbook existingWorkBook = new XSSFWorkbook(new File("fileName.xlsx"));

Manage sheets

XSSFWorkbook class provides different methods for sheet management: createSheet(), cloneSheet(), getNumberOfSheets(), getSheet(), getSheetAt(), getSheetName()getSheetIndex(). Create or get sheet methods return a XSSFSheet object.

Manage sheet content

Once you have the XSSFSheet object, either from create or get, you can manage rows in it. Some of the methods are: createRow()getRow(), removeRow(), getLastRowNum(), getPhysicalNumberOfRows()rowIterator(). Create or get row methods return a XSSFRow object. Inside row you can manage cells. Some of the methods are: createCell(), getCell(), removeCell(), getLastCellNum(), getPhysicalNumberOfCells(), cellIterator(). Create or get cell methods return a XSSFCell object. Some the methods are: setCellComment(), setCellFormula(), setCellStyle(), setCellType(), setCellValue().

Manage Excel documents

Bellow are shown examples of simple ExcelWriter class that writes to Excel file. This class is used in SampleExcelApp showing how to write the text. Reading from Excel is shown in SampleExcelAppTest verifying the correct saving of the document.

ExcelWriter

package com.automationrhapsody.apachepoi;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import org.apache.poi.ss.usermodel.CellType;
import org.apache.poi.ss.usermodel.FillPatternType;
import org.apache.poi.ss.usermodel.IndexedColors;
import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFCellStyle;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExcelWriter {

	private final XSSFWorkbook workBook;

	private Map<String, Integer> nextRows = new HashMap<>();
	private String currentSheet;
	private boolean isSaved;

	public ExcelWriter() {
		workBook = new XSSFWorkbook();
	}

	public void writeAndClose(File excelFile) {
		if (isSaved) {
			throw new IllegalArgumentException("Workbook already saved!");
		}
		try {
			workBook.write(new FileOutputStream(excelFile));
			workBook.close();
			isSaved = true;
		} catch (IOException ioe) {
			// TODO log
		}
	}

	public void switchToSheet(String sheetName) {
		currentSheet = sheetName;
		if (workBook.getSheet(sheetName) == null) {
			workBook.createSheet(currentSheet);
			nextRows.put(currentSheet, 0);
		}
	}

	public void writeRow(String... values) {
		XSSFSheet sheet = workBook.getSheet(currentSheet);
		int nextRow = nextRows.get(currentSheet);
		XSSFRow row = sheet.createRow(nextRow);

		for (int i = 0; i < values.length; i++) { 
			XSSFCell cell = row.createCell(i);
			cell.setCellType(CellType.STRING);
			cell.setCellValue(values[i]);
		}

		nextRows.put(currentSheet, nextRow + 1);
	}

	public void setCellColour(int rowNumber, int cellNumber,
			IndexedColors colour) {
		XSSFCellStyle style = workBook.createCellStyle();
		style.setFillForegroundColor(colour.getIndex());
		style.setFillPattern(FillPatternType.SOLID_FOREGROUND);

		int nextRow = nextRows.get(currentSheet); if (rowNumber > nextRow) {
			// TODO log or exception?
			rowNumber = nextRow;
		}
		XSSFSheet sheet = workBook.getSheet(currentSheet);
		int lastCell = sheet.getRow(rowNumber - 1).getLastCellNum();
		if (cellNumber > lastCell) {
			// TODO log or exception?
			cellNumber = lastCell;
		}

		sheet.getRow(rowNumber - 1).getCell(cellNumber - 1)
			.setCellStyle(style);
	}
}

SampleExcelApp

package com.automationrhapsody.apachepoi;

import java.io.File;

import org.apache.poi.ss.usermodel.IndexedColors;

public class SampleExcelApp {

	public static void main(String[] args) {
		String sheetName = "SheetName";

		ExcelWriter excelWriter = new ExcelWriter();
		excelWriter.switchToSheet(sheetName);
		excelWriter.writeRow("A1-blue", "B1", "C1");
		excelWriter.writeRow("A2", "B2", "C2");
		excelWriter.setCellColour(1, 1, IndexedColors.BLUE);

		excelWriter.switchToSheet("NewSheetName");
		excelWriter.writeRow("A1", "B1");
		excelWriter.writeRow("A2", "B2-red");
		excelWriter.setCellColour(2, 2, IndexedColors.RED);

		excelWriter.switchToSheet(sheetName);
		excelWriter.writeRow("A3", "B3", "C3");
		excelWriter.writeRow("A4", "B4", "C4");

		File excelFile = new File("testReport.xlsx");
		excelWriter.writeAndClose(excelFile);
	}
}

SampleExcelAppTest

package com.automationrhapsody.apachepoi;

import java.io.File;

import org.apache.poi.ss.usermodel.IndexedColors;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.junit.BeforeClass;
import org.junit.Test;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.is;

public class SampleExcelAppTest {

	private static final File FILE = new File("testReport.xlsx");

	private static XSSFWorkbook workbookUnderTest;

	@BeforeClass
	public static void beforeClass() throws Exception {
		if (FILE.exists()) {
			FILE.delete();
		}

		App.main(null);

		workbookUnderTest = new XSSFWorkbook(FILE);
	}

	@Test
	public void testNumberOfSheets() {
		assertThat(workbookUnderTest.getNumberOfSheets(), is(2));
	}

	@Test
	public void testSheetName() {
		assertThat(workbookUnderTest.getSheetName(0), is("SheetName"));
		assertThat(workbookUnderTest.getSheetName(1), is("NewSheetName"));
	}

	@Test
	public void testFirstSheetContent() {
		XSSFSheet sheet = workbookUnderTest.getSheetAt(0);
		assertThat(sheet.getLastRowNum(), is(3));
		assertThat(sheet.getRow(3).getLastCellNum(), is((short) 3));
		assertThat(sheet.getRow(3).getCell(2).getStringCellValue(), 
				is("C4"));

		assertThat(sheet.getRow(0).getCell(0).getCellStyle()
			.getFillForegroundColor(), is(IndexedColors.BLUE.getIndex()));
		assertThat(sheet.getRow(1).getCell(1).getCellStyle()
			.getFillForegroundColor(), 
				is(IndexedColors.AUTOMATIC.getIndex()));
	}

	@Test
	public void testSecondSheetContent() {
		XSSFSheet sheet = workbookUnderTest.getSheetAt(1);
		assertThat(sheet.getLastRowNum(), is(1));
		assertThat(sheet.getRow(1).getLastCellNum(), is((short) 2));
		assertThat(sheet.getRow(1).getCell(1).getStringCellValue(), 
				is("B2-red"));

		assertThat(sheet.getRow(1).getCell(1).getCellStyle()
			.getFillForegroundColor(), is(IndexedColors.RED.getIndex()));
		assertThat(sheet.getRow(0).getCell(0).getCellStyle()
			.getFillForegroundColor(), 
				is(IndexedColors.AUTOMATIC.getIndex()));
	}
}

Conclusion

Apache POI is very powerful toolkit for managing MS documents especially Excel, which might be needed in you test automation for reporting of data driven testing.

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