update Logging Interceptor to log connection failures

okhttp-logging-interceptor/src/main/java/okhttp3/logging/HttpLoggingInterceptor.java

@@ -207,7 +207,13 @@ public final class HttpLoggingInterceptor implements Interceptor {
     }
 
     long startNs = System.nanoTime();
-    Response response = chain.proceed(request);
+    Response response;
+    try {
+      response = chain.proceed(request);
+    } catch (Exception e) {
+      logger.log("<-- HTTP FAILED: " + e);
+      throw e;
+    }
     long tookMs = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startNs);
 
     ResponseBody responseBody = response.body();

okhttp-logging-interceptor/src/test/java/okhttp3/logging/HttpLoggingInterceptorTest.java

@@ -16,9 +16,12 @@
 package okhttp3.logging;
 
 import java.io.IOException;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.regex.Pattern;
+import okhttp3.Dns;
 import okhttp3.HttpUrl;
 import okhttp3.MediaType;
 import okhttp3.OkHttpClient;
@@ -641,6 +644,29 @@ public final class HttpLoggingInterceptorTest {
         .assertNoMoreLogs();
   }
 
+  @Test public void connectFail() throws IOException {
+    setLevel(Level.BASIC);
+    client = new OkHttpClient.Builder()
+        .dns(new Dns() {
+          @Override public List<InetAddress> lookup(String hostname) throws UnknownHostException {
+            throw new UnknownHostException("reason");
+          }
+        })
+        .addInterceptor(applicationInterceptor)
+        .build();
+
+    try {
+      client.newCall(request().build()).execute();
+      fail();
+    } catch (UnknownHostException expected) {
+    }
+
+    applicationLogs
+        .assertLogEqual("--> GET " + url + " http/1.1")
+        .assertLogEqual("<-- HTTP FAILED: java.net.UnknownHostException: reason")
+        .assertNoMoreLogs();
+  }
+
   private Request.Builder request() {
     return new Request.Builder().url(url);
   }