how to mock a URL connection

Question

Hi I have a method that takes an URL as an input and determines if it is reachable. Heres the code for that:

public static boolean isUrlAccessible(final Str         


        

Answer 1

It's much simpler with the JMockit mocking API (and even simpler with no mocking):

import java.io.*;
import java.net.*;
import org.junit.*;
import static org.junit.Assert.*;
import mockit.*;

public final class ExampleURLTest {
   public static final class ClassUnderTest {
      public static boolean isUrlAccessible(String urlToValidate) throws IOException {
         HttpURLConnection huc = null;
         int responseCode;

         try {
            URL url = new URL(urlToValidate);
            huc = (HttpURLConnection) url.openConnection();
            huc.setRequestMethod("HEAD");
            huc.connect();
            responseCode = huc.getResponseCode();
         }
         finally {
            if (huc != null) {
               huc.disconnect();
            }
         }

         return responseCode == 200;
      }
   }

   // Proper tests, no unnecessary mocking ///////////////////////////////////////

   @Test
   public void checkAccessibleUrl() throws Exception {
      boolean accessible = ClassUnderTest.isUrlAccessible("http://google.com");

      assertTrue(accessible);
   }

   @Test(expected = UnknownHostException.class)
   public void checkInaccessibleUrl() throws Exception {
      ClassUnderTest.isUrlAccessible("http://inaccessible12345.com");
   }

   @Test
   public void checkUrlWhichReturnsUnexpectedResponseCode(
      @Mocked URL anyURL, @Mocked HttpURLConnection mockConn
   ) throws Exception {
      new Expectations() {{ mockConn.getResponseCode(); result = -1; }};

      boolean accessible = ClassUnderTest.isUrlAccessible("http://invalidResource.com");

      assertFalse(accessible);
   }

   // Lame tests with unnecessary mocking ////////////////////////////////////////

   @Test
   public void checkAccessibleUrl_withUnnecessaryMocking(
      @Mocked URL anyURL, @Mocked HttpURLConnection mockConn
   ) throws Exception {
      new Expectations() {{ mockConn.getResponseCode(); result = 200; }};

      boolean accessible = ClassUnderTest.isUrlAccessible("http://google.com");

      assertTrue(accessible);
   }

   @Test(expected = UnknownHostException.class)
   public void checkInaccessibleUrl_withUnnecessaryMocking(
      @Mocked URL anyURL, @Mocked HttpURLConnection mockConn
   ) throws Exception {
      new Expectations() {{ mockConn.connect(); result = new UnknownHostException(); }};

      ClassUnderTest.isUrlAccessible("http://inaccessible12345.com");
   }
}

(Verified with JMockit 1.47 on JDKs 8 & 9.)