如何使用Mockito消除外部依赖？

Question

下面是我的html" target="_blank">代码：

// WeatherDemo.java:

package com.abc;

public class WeatherDemo {
    public String getForecast() {
        // Get the high remperature for today, and return back to the caller one of these values:
        // cold, mild, or hot
        // cold will be returned if the high temp is forecast to be less than 60.
        // hot will be returned if the high temp is forecast to be more than 79.
        // Otherwise, mild will be returned (this indicates a high temp in the 60s or 70s).
        int highTemp = getHighTemp();
        if (highTemp < 60)
            return("cold");
        if (highTemp > 79)
            return("hot");
        return("mild");
    }

    public int getHighTemp() {
        // Because this is a demo, we don't have access to any source (web service, DB, etc.) to get the high temp.
        // Just hard code a value here, but remember that if this were a real application, we would be dynamically
        //   retrieving the day's high temperature from some external source.
        int highTemp = 32;
        return(highTemp);
    }
}

===================================================================================================

// TestWeatherDemo.java:

package com.abc;

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

public class TestWeatherDemo {
    @Test
    public void testWeatherReport() {
        WeatherDemo testMockito = Mockito.mock(WeatherDemo.class);
        WeatherDemo testJUnit = new WeatherDemo();

        when(testMockito.getHighTemp()).thenReturn(90);
        assertEquals("hot", testJUnit.getForecast());
    }
}

===================================================================================================

Mockito背后的全部思想难道不是我可以模拟一个方法，并告诉它确切地返回什么，以消除外部依赖关系吗？如果从getForecast（）调用getHightTemp（）不会返回90，我就看不出Mockito的用途了。我在这里漏掉了什么？谢谢你的帮助和启迪。

账单

Answer 1

在您的示例中，TestMockito和TestJunit是不同的对象-您在TestMockito上模拟了方法，但是TestJunit有方法的实际实现，返回32。

您可能需要考虑将代码分成两个类，然后可以使gethightemp()中的代码成为主类的依赖项。这是在测试中提供模拟和实际运行代码的真正实现的地方。（也许通过某种依赖注入）

以这种方式构建的代码似乎遵循了单一责任原则--这样做的好处是，如果您需要更改天气数据供应商，它将使您的工作变得更加容易。我认为，当您说“因为这是一个外部资源，所以我的Junit没有通过隔离测试”时，您无论如何都是沿着这条线走的。