cs108 java 02

Eclipise

1. import, 所有的homework 是以 eclipse project directories 的形式.

   所以要选择 “File –> Import “, Existing project “, 选择 “copy to workspace” option will copy the project directory into Eclipse’s workspace directory.

2. debugging

   double click in the editor at the left of a line to set a breakpoint on that line.

   Use “Debug” instead of “Run” to run in the debugger.

3. Eclipse 特性

  

看自己总结的eclipse快捷键更好一点.

Unit test( 单元测试 )

Unit test 的目的, for each piece of "work" code --a class or a method, pair the work code with some "unit test" code ( 每完成一个类或方法就测试一下 )

这种测试不用是 "exhaustive", 非常完整的测试, 功能实现没问题, 基本数据测试就可以了.

Unit tests are a standard, maintained way to keep tests in parallel with the work code

只要测试一些明显的, 基本的数据就可以了.

Right-click on the class to be tested.

Junit 很流行, new-> JUnit Test case, 比如类名为 Binky, 那么测试的类名为 BinkyTest. (自动生成的)

这个生成是在本 project 内完成的.

Junit 依赖一些类, file: junit.jar 添加的办法: -自动添加-, 当你选择new->Junit Test case时, 如果第一次, eclipse会提示你让你安装 Junit.jar, -手动安装-, properities, –> Java Build Path –> Libraries –> Add Jar button .

测试方法的话, 比如方法名叫 Foo, 那么测试的方法名为 testFoo(), 像下边的

@Test

public void testFoo() {}

Example 1

1. CLASS

import java.util.*;

/*
 * Emails class -- unit testing example.
 * Encapsulates some text with email address in it.
 * getUsers() returns a list of the usernames from the text. 
 */
public class Emails {
    
    // Sets up a new Emails obj with the given text

    public Emails(String text) {
        this.text = text;
    }
    
    // Returns a list of the usernames found in the text.
    // We'll say that a username is one or more letters, digits,
    // or dots to the left of a @.
    
    public List<String> getUsers() {
        int pos = 0;
        List<String> users = new ArrayList<String>();
        
        while (true) {
            int at = text.indexOf('@', pos);
            if (at == -1) break;
            
            // Look backwards from at
            int back = at - 1;
            while (back >=0 &&
                    (Character.isLetterOrDigit(text.charAt(back)) || text.charAt(back) == '.')) {
                back--;
            } 
            // Now back is before start of username
            String user = text.substring(back+1, at);
            
            if (user.length() > 0) users.add(user);
            
            // Advance pos for next time
            pos = at + 1;
            
        }
        return users;
    }

    /* private values */    
    private String text;
    
}

2. TEST CLASS

import static org.junit.Assert.assertEquals;

import java.util.Arrays;
import java.util.Collections;

import org.junit.Test;

/**
 * EmailsTest -- unit tests for the Emails class.
 * @author Ronnie
 *
 */
public class EmailsTest {

    // Basic use
    @Test
    public void testUsersBasic() {
        Emails emails = new Emails("foo bart@cs.edu xyz marge@ms.com baz");
        assertEquals(Arrays.asList("bart", "marge"), emails.getUsers());
        // Note: Array.asList(...) is a handy way to make list literal.
        // Also note that .equals() works for collections, so the above works.
    }
    
    // Weird chars -- push on what chars are allowed
    @Test
    public void testUsersChars() {
        Emails emails = new Emails("fo f.ast@cs.edu bar&a.2.c@ms.com");
        assertEquals(Arrays.asList("f.ast", "a.2.c"), emails.getUsers());
    }
    
    // Hard cases -- push on unusual, edge cases
    @Test
    public void testUsersHard() {
        Emails emails = new Emails("x y@cs 3@ @z@");
        assertEquals(Arrays.asList("y", "3", "z"), emails.getUsers());
        
        // No emails
        emails = new Emails("no emails here!");
        assertEquals(Collections.emptyList(), emails.getUsers());
        
        // All @, all the time!
        emails = new Emails("@@@");
        assertEquals(Collections.emptyList(), emails.getUsers());
        
        // Empty string
        emails = new Emails("");
        assertEquals(Collections.emptyList(), emails.getUsers());
        
    }
    
    
}

Example 2

public class Myunit {
    public String concatenate(String one, String two) {
        return one + two;
    }
}


//========================================

import static org.junit.Assert.*;

import org.junit.Test;


public class MyunitTest {

    @Test
    public void testConcatenate() {
        Myunit myUnit = new Myunit();
        
        String result = myUnit.concatenate("one", "two");
        assertEquals("onetwo", result);
    }

}

以上代码中, Unit Test 目的是测试所有的 public 方法, 在上例中, 只有1个public 方法就是 concatenate, 一般来讲, 每个测试方法对应一个方法, 命名方式为 test该方法名, 例如 testConcatenate, 但是也有几个测试方法对应一个方法的情况, 比如要测试的方法很大. assertEquals 很明显是用来比较的, 比较你要的结果是否和程序得出的结果一直. The asserEquals() method is a statically imported method, which normally resides in the org.junit.Assert class.

用来测试的方法上边有个 @Test 用来注释,表示这个方法是一个 unit test.  注意这样有一个好处就是, 这个方法在eclipse中可以运行(没有 main 方法 ), 如果没有这个@Test标志, 那么这个测试方法将无法运行.