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📜  JUnit-使用断言

📅  最后修改于: 2020-11-12 04:39:01             🧑  作者: Mango

断言

所有的断言都在Assert类中。

public class Assert extends java.lang.Object

此类提供了一组断言方法，可用于编写测试。仅记录失败的断言。 Assert类的一些重要方法如下-

Sr.No. Methods & Description
1

void assertEquals(boolean expected, boolean actual)

Checks that two primitives/objects are equal.
2

void assertTrue(boolean condition)

Checks that a condition is true.
3

void assertFalse(boolean condition)

Checks that a condition is false.
4

void assertNotNull(Object object)

Checks that an object isn’t null.
5

void assertNull(Object object)

Checks that an object is null.
6

void assertSame(object1, object2)

The assertSame() method tests if two object references point to the same object.
7

void assertNotSame(object1, object2)

The assertNotSame() method tests if two object references do not point to the same object.
8

void assertArrayEquals(expectedArray, resultArray);

The assertArrayEquals() method will test whether two arrays are equal to each other.

让我们在示例中使用一些上述方法。在C：\> JUNIT_WORKSPACE中创建一个名为TestAssertions.java的Java类文件。

import org.junit.Test;
import static org.junit.Assert.*;

public class TestAssertions {

   @Test
   public void testAssertions() {
      //test data
      String str1 = new String ("abc");
      String str2 = new String ("abc");
      String str3 = null;
      String str4 = "abc";
      String str5 = "abc";
        
      int val1 = 5;
      int val2 = 6;

      String[] expectedArray = {"one", "two", "three"};
      String[] resultArray =  {"one", "two", "three"};

      //Check that two objects are equal
      assertEquals(str1, str2);

      //Check that a condition is true
      assertTrue (val1 < val2);

      //Check that a condition is false
      assertFalse(val1 > val2);

      //Check that an object isn't null
      assertNotNull(str1);

      //Check that an object is null
      assertNull(str3);

      //Check if two object references point to the same object
      assertSame(str4,str5);

      //Check if two object references not point to the same object
      assertNotSame(str1,str3);

      //Check whether two arrays are equal to each other.
      assertArrayEquals(expectedArray, resultArray);
   }
}

接下来，在C：\> JUNIT_WORKSPACE中创建一个名为TestRunner.java的Java类文件以执行测试用例。

import org.junit.runner.JUnitCore;
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;

public class TestRunner2 {
   public static void main(String[] args) {
      Result result = JUnitCore.runClasses(TestAssertions.class);
        
      for (Failure failure : result.getFailures()) {
         System.out.println(failure.toString());
      }
        
      System.out.println(result.wasSuccessful());
   }
}

使用javac编译测试用例和测试运行器类。

C:\JUNIT_WORKSPACE>javac TestAssertions.java TestRunner.java

现在运行Test Runner，它将运行在提供的Test Case类中定义的测试用例。

C:\JUNIT_WORKSPACE>java TestRunner

验证输出。

true

注解

注释就像元标记，您可以将其添加到代码中并将其应用于方法或类中。 JUnit中的这些注释提供了有关测试方法的以下信息-

  • 哪些方法将在测试方法之前和之后运行。
  • 哪些方法在所有方法之前和之后运行，以及。
  • 执行期间将忽略哪些方法或类。

下表提供了注释及其在JUnit中的含义的列表-

Sr.No. Annotation & Description
1

@Test

The Test annotation tells JUnit that the public void method to which it is attached can be run as a test case.
2

@Before

Several tests need similar objects created before they can run. Annotating a public void method with @Before causes that method to be run before each Test method.
3

@After

If you allocate external resources in a Before method, you need to release them after the test runs. Annotating a public void method with @After causes that method to be run after the Test method.
4

@BeforeClass

Annotating a public static void method with @BeforeClass causes it to be run once before any of the test methods in the class.
5

@AfterClass

This will perform the method after all tests have finished. This can be used to perform clean-up activities.
6

@Ignore

The Ignore annotation is used to ignore the test and that test will not be executed.

在C：\> JUNIT_WORKSPACE中创建一个名为JunitAnnotation.java的Java类文件以测试注释。

import org.junit.After;
import org.junit.AfterClass;

import org.junit.Before;
import org.junit.BeforeClass;

import org.junit.Ignore;
import org.junit.Test;

public class JunitAnnotation {
    
   //execute before class
   @BeforeClass
   public static void beforeClass() {
      System.out.println("in before class");
   }

   //execute after class
   @AfterClass
   public static void  afterClass() {
      System.out.println("in after class");
   }

   //execute before test
   @Before
   public void before() {
      System.out.println("in before");
   }
    
   //execute after test
   @After
   public void after() {
      System.out.println("in after");
   }
    
   //test case
   @Test
   public void test() {
      System.out.println("in test");
   }
    
   //test case ignore and will not execute
   @Ignore
   public void ignoreTest() {
      System.out.println("in ignore test");
   }
}

接下来，在C：\> JUNIT_WORKSPACE中创建一个名为TestRunner.java的Java类文件以执行注释。

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(JunitAnnotation.class);
        
      for (Failure failure : result.getFailures()) {
         System.out.println(failure.toString());
      }
        
      System.out.println(result.wasSuccessful());
   }
}

使用javac编译测试用例和测试运行器类。

C:\JUNIT_WORKSPACE>javac JunitAnnotation.java TestRunner.java

现在运行Test Runner，它将运行在提供的Test Case类中定义的测试用例。

C:\JUNIT_WORKSPACE>java TestRunner

验证输出。

in before class
in before
in test
in after
in after class
true