Java 如何编写静态void方法的单元测试

我面临一个问题，我不知道如何编写静态void方法的单元测试

我现在有一个使用ApacheHttpClient的HttpHelper类。代码如下

public class HttpHelper {
    private static CloseableHttpClient httpClient;

    public static void init() {
        httpClient = HttpClients.custom().setSSLContext(getDummySSL()).build();
    }

    public static void closeHttpClient() throws IOException {
        httpClient.close();
    }

    private static SSLContext getDummySSL() {
        ...omit
    }

    private static void send() {
        HttpGet httpGet = new HttpGet("https://someUrl.com");

        try(CloseableHttpResponse httpResponse = httpClient.execute(httpGet)) {
            if(httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                responseString = EntityUtils.toString(httpResponse.getEntity());
                // do something
            } else {
                throw new Exception();
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

因此，在我的主要部分中，我将调用

HttpHelper.init（）

来初始化httpClient。每次我想发送请求时，我都会调用

HttpHelper.send（）

。因为我不想每次都创建一个新的httpClient。最后，我将调用

HttpHelper.close（）

关闭httpClient

我想知道如何测试这些无效的方法。我的概念是在测试中创建一个

CloseableHttpClient

，然后调用

HttpHelper.init（）

来创建实际的一个。然后比较我的期望值和实际值是否相同。我说得对吗

由于变量和方法被声明为静态。编写单元测试有点困难。有很多帖子说，将方法设置为静态是一种不好的做法。然而，在我的示例中，我不知道如何避免将它们声明为静态并保留单个

CloseableHttpClient

实例

---

谢谢大家!

单实例保证主要通过单实例模式解决。单元测试的一个常见技巧是使构造函数具有受保护的可视性，您可以在其中放置用于测试的参数。这个班终于可以这样了

public class HttpHelper {
    private static HttpHelper INSTANCE = new HttpHelper();

    public static HttpHelper getInstance() {
        return INSTANCE;
    }


    private CloseableHttpClient httpClient;

    private HttpHelper() {
        SSLContext sslContext = getDummySSL();
        this(HttpClients.custom().setSSLContext(sslContext).build(), sslContext);
    }

    protected HttpHelper(CloseableHttpClient httpClient, SSLContext sslContext) {
        this.httpClient = httpClient;
    }

    public void closeHttpClient() throws IOException {
        httpClient.close();
    }

    private static SSLContext getDummySSL() {
        ...
    }

    private void send() {
        ...
    }
}

---

我还想将

getdummysl

重命名为

createdummysl

，但这是一个细节。

拥有一个如此静态的类是不好的，因为很难测试它。我理解你为什么想要这个，但你可以得到同样的好处：

public class HttpHelper {

    private static HttpHelper DEFAULT_INSTANCE = null;

    private CloseableHttpClient httpClient;

    public HttpHelper(CloseableHttpClient httpClient) {
        this.httpClient = httpClient;
    }

    public static void getDeafultInstance() { // this should probably be synchronised for thread safety
        if (DEFAULT_INSTANCE == null) {
            DEFAULT_INSTANCE = httpClient = HttpClients.custom().setSSLContext(getDummySSL()).build();
        }
        return DEAFULT_INSTANCE;
    }

    private static SSLContext getDummySSL() {
        ...omit
    }

    public void closeHttpClient() throws IOException {
        httpClient.close();
    }

    private void send() {
        HttpGet httpGet = new HttpGet("https://someUrl.com");

        try(CloseableHttpResponse httpResponse = httpClient.execute(httpGet)) {
            if(httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                responseString = EntityUtils.toString(httpResponse.getEntity());
                // do something
            } else {
                throw new Exception();
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public class HttpHelperTest {

    @Test
    public testSendsRequestToSomeUrl() {
        CloseableHttpClient httpClientMock = mock();
        when(httpClient.execute(any())).thenReturn(..http_response_where_stauts_code_is_ok..)
        HttpHelper httpHelper = new HttpHelper(httpClientMock)
        httpHelper.send()
        verify(httpClient).execute(new HttpGet("https://someUrl.com"))
    }

}

HttpHelper.getDeafultInstance().send()

然后您可以这样进行单元测试：

public class HttpHelper {

    private static HttpHelper DEFAULT_INSTANCE = null;

    private CloseableHttpClient httpClient;

    public HttpHelper(CloseableHttpClient httpClient) {
        this.httpClient = httpClient;
    }

    public static void getDeafultInstance() { // this should probably be synchronised for thread safety
        if (DEFAULT_INSTANCE == null) {
            DEFAULT_INSTANCE = httpClient = HttpClients.custom().setSSLContext(getDummySSL()).build();
        }
        return DEAFULT_INSTANCE;
    }

    private static SSLContext getDummySSL() {
        ...omit
    }

    public void closeHttpClient() throws IOException {
        httpClient.close();
    }

    private void send() {
        HttpGet httpGet = new HttpGet("https://someUrl.com");

        try(CloseableHttpResponse httpResponse = httpClient.execute(httpGet)) {
            if(httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                responseString = EntityUtils.toString(httpResponse.getEntity());
                // do something
            } else {
                throw new Exception();
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public class HttpHelperTest {

    @Test
    public testSendsRequestToSomeUrl() {
        CloseableHttpClient httpClientMock = mock();
        when(httpClient.execute(any())).thenReturn(..http_response_where_stauts_code_is_ok..)
        HttpHelper httpHelper = new HttpHelper(httpClientMock)
        httpHelper.send()
        verify(httpClient).execute(new HttpGet("https://someUrl.com"))
    }

}

HttpHelper.getDeafultInstance().send()

并在实际代码中使用它，如下所示：

public class HttpHelper {

    private static HttpHelper DEFAULT_INSTANCE = null;

    private CloseableHttpClient httpClient;

    public HttpHelper(CloseableHttpClient httpClient) {
        this.httpClient = httpClient;
    }

    public static void getDeafultInstance() { // this should probably be synchronised for thread safety
        if (DEFAULT_INSTANCE == null) {
            DEFAULT_INSTANCE = httpClient = HttpClients.custom().setSSLContext(getDummySSL()).build();
        }
        return DEAFULT_INSTANCE;
    }

    private static SSLContext getDummySSL() {
        ...omit
    }

    public void closeHttpClient() throws IOException {
        httpClient.close();
    }

    private void send() {
        HttpGet httpGet = new HttpGet("https://someUrl.com");

        try(CloseableHttpResponse httpResponse = httpClient.execute(httpGet)) {
            if(httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                responseString = EntityUtils.toString(httpResponse.getEntity());
                // do something
            } else {
                throw new Exception();
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public class HttpHelperTest {

    @Test
    public testSendsRequestToSomeUrl() {
        CloseableHttpClient httpClientMock = mock();
        when(httpClient.execute(any())).thenReturn(..http_response_where_stauts_code_is_ok..)
        HttpHelper httpHelper = new HttpHelper(httpClientMock)
        httpHelper.send()
        verify(httpClient).execute(new HttpGet("https://someUrl.com"))
    }

}

HttpHelper.getDeafultInstance().send()

附言

---

如果您有某种依赖注入框架可用，那么您就可以完全摆脱静态方法。

单元测试的痛苦通常表明有代码气味。可能将

httpClient

传递到

send（）

（因此

httpClient

可以轻松模拟），或者更改为非静态，并注入

httpClient

（因此

httpClient

可以轻松模拟）。您好，感谢您的回复。但如果我这样做的话。也许

httpClient

无法保留单个实例？