我正在尝试为一个需要用户输入的方法创建一些JUnit测试。被测试的方法看起来有点像下面的方法:
public static int testUserInput() {
Scanner keyboard = new Scanner(System.in);
System.out.println("Give a number between 1 and 10");
int input = keyboard.nextInt();
while (input < 1 || input > 10) {
System.out.println("Wrong number, try again.");
input = keyboard.nextInt();
}
return input;
}
有没有可能自动向程序传递一个int,而不是我或其他人在JUnit测试方法中手动执行此操作?比如模拟用户输入?
提前谢谢。
发布于 2011-06-21 03:11:12
您可以替换System.in with you own stream by calling System.setIn(InputStream in)。InputStream可以是字节数组:
InputStream sysInBackup = System.in; // backup System.in to restore it later
ByteArrayInputStream in = new ByteArrayInputStream("My string".getBytes());
System.setIn(in);
// do your thing
// optionally, reset System.in to its original
System.setIn(sysInBackup);
不同方法可以通过传入和传出作为参数来使此方法更具可测试性:
public static int testUserInput(InputStream in,PrintStream out) {
Scanner keyboard = new Scanner(in);
out.println("Give a number between 1 and 10");
int input = keyboard.nextInt();
while (input < 1 || input > 10) {
out.println("Wrong number, try again.");
input = keyboard.nextInt();
}
return input;
}
发布于 2011-06-21 03:46:40
为了测试你的代码,你应该为系统输入/输出函数创建一个包装器。你可以使用依赖注入来做这件事,给我们一个可以请求新整数的类:
public static class IntegerAsker {
private final Scanner scanner;
private final PrintStream out;
public IntegerAsker(InputStream in, PrintStream out) {
scanner = new Scanner(in);
this.out = out;
}
public int ask(String message) {
out.println(message);
return scanner.nextInt();
}
}
然后,您可以使用模拟框架(我使用Mockito)为您的函数创建测试:
@Test
public void getsIntegerWhenWithinBoundsOfOneToTen() throws Exception {
IntegerAsker asker = mock(IntegerAsker.class);
when(asker.ask(anyString())).thenReturn(3);
assertEquals(getBoundIntegerFromUser(asker), 3);
}
@Test
public void asksForNewIntegerWhenOutsideBoundsOfOneToTen() throws Exception {
IntegerAsker asker = mock(IntegerAsker.class);
when(asker.ask("Give a number between 1 and 10")).thenReturn(99);
when(asker.ask("Wrong number, try again.")).thenReturn(3);
getBoundIntegerFromUser(asker);
verify(asker).ask("Wrong number, try again.");
}
然后编写通过测试的函数。这个函数要干净得多,因为您可以删除询问/获取整数的重复,并且实际的系统调用是封装的。
public static void main(String[] args) {
getBoundIntegerFromUser(new IntegerAsker(System.in, System.out));
}
public static int getBoundIntegerFromUser(IntegerAsker asker) {
int input = asker.ask("Give a number between 1 and 10");
while (input < 1 || input > 10)
input = asker.ask("Wrong number, try again.");
return input;
}
对于您的小示例来说,这可能看起来有点过头了,但如果您正在构建一个更大的应用程序,那么开发这样的应用程序可能会相当快地获得回报。
发布于 2014-04-29 11:11:22
测试类似代码的一种常见方法是提取一个接受扫描器和PrintWriter (类似于this StackOverflow answer )的方法,并测试该方法:
public void processUserInput() {
processUserInput(new Scanner(System.in), System.out);
}
/** For testing. Package-private if possible. */
public void processUserInput(Scanner scanner, PrintWriter output) {
output.println("Give a number between 1 and 10");
int input = scanner.nextInt();
while (input < 1 || input > 10) {
output.println("Wrong number, try again.");
input = scanner.nextInt();
}
return input;
}
请注意,直到最后才能读取输出,并且必须在前面指定所有输入:
@Test
public void shouldProcessUserInput() {
StringWriter output = new StringWriter();
String input = "11\n" // "Wrong number, try again."
+ "10\n";
assertEquals(10, systemUnderTest.processUserInput(
new Scanner(input), new PrintWriter(output)));
assertThat(output.toString(), contains("Wrong number, try again.")););
}
当然,您也可以将"scanner“和"output”作为系统中的可变字段进行测试,而不是创建一个重载方法。我倾向于尽可能保持类的无状态,但如果这对您或您的同事/讲师很重要,这并不是一个很大的让步。
您还可以选择将测试代码放在与测试代码相同的Java包中(即使它位于不同的源文件夹中),这允许您将两个参数重载的可见性放宽为包私有。
https://stackoverflow.com/questions/6415728
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