Include URL in loadJSON and loadJSONHTML exception messages

Includes the basename of the original exception and the message of the
original exception so that the exception message retains the information
from the original exception.

Without the original exception message and exception class, it can be
difficult to understand the cause of the message.  Was it a connection
timeout or a connection reset or a hostname not found or something else?

Author: MarkEWaite

core/src/main/java/hudson/PluginManager.java

@@ -2177,15 +2177,13 @@ private FormValidation checkUpdatesServer() throws Exception {
             FormValidation v = site.updateDirectlyNow();
             if (v.kind != FormValidation.Kind.OK) {
                 // Stop with an error
-                LOGGER.log(Level.SEVERE, "Failed to check updates server:  " + site.getUrl());
                 return v;
             }
         }
         for (DownloadService.Downloadable d : DownloadService.Downloadable.all()) {
             FormValidation v = d.updateNow();
             if (v.kind != FormValidation.Kind.OK) {
                 // Stop with an error
-                LOGGER.log(Level.SEVERE, "Failed to update downloadable: " + d.getUrl());
                 return v;
             }
         }

core/src/main/java/hudson/model/DownloadService.java

@@ -128,6 +128,13 @@ public static String loadJSON(URL src) throws IOException {
             } else {
                 throw new IOException("Could not find JSON in " + src);
             }
+        } catch (IOException ioe) {
+            // Include basename of exception and original message text
+            // in the new message so that the person reading the
+            // message understands the exception type and the text
+            // provided by the original exception.
+            String ioeMessage = ioe.getClass().getSimpleName() + ": " + ioe.getMessage();
+            throw new IOException("Could not load JSON from " + src + " due to " + ioeMessage);
         }
     }
 
@@ -154,6 +161,13 @@ public static String loadJSONHTML(URL src) throws IOException {
             } else {
                 throw new IOException("Could not find JSON in " + src);
             }
+        } catch (IOException ioe) {
+            // Include basename of exception and original message text
+            // in the new message so that the person reading the
+            // message understands the exception type and the text
+            // provided by the original exception.
+            String ioeMessage = ioe.getClass().getSimpleName() + ": " + ioe.getMessage();
+            throw new IOException("Could not load JSON as HTML from " + src + " due to " + ioeMessage);
         }
     }
 

test/src/test/java/hudson/model/DownloadServiceTest.java

@@ -1,14 +1,19 @@
 package hudson.model;
 
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import edu.umd.cs.findbugs.annotations.NonNull;
 import hudson.model.DownloadService.Downloadable;
 import hudson.tasks.Ant.AntInstaller;
 import hudson.tasks.Maven;
 import hudson.tools.DownloadFromUrlInstaller;
 import hudson.tools.ToolInstallation;
+import java.io.IOException;
+import java.net.URI;
 import java.net.URL;
 import java.util.ArrayList;
 import java.util.List;
@@ -38,6 +43,26 @@ private static void assertRoots(String expected, URL resource) throws Exception
         assertEquals(expected, new TreeSet<>(keySet).toString());
     }
 
+    @WithoutJenkins
+    @Test
+    void testLoadJSONException() throws Exception {
+        String badHostname = "bad.updates.jenkins.io"; // Non-existent host
+        URL badURL = new URI("https://" + badHostname + "/update-center.json").toURL();
+        IOException e = assertThrows(IOException.class, () -> DownloadService.loadJSON(badURL));
+        assertThat(e.getMessage(), containsString(badURL.toString()));
+        assertThat(e.getMessage(), containsString("due to UnknownHostException:"));
+    }
+
+    @WithoutJenkins
+    @Test
+    void testLoadJSONHTMLException() throws Exception {
+        String badHostname = "bad.updates.jenkins.io"; // Non-existent host
+        URL badURL = new URI("https://" + badHostname + "/update-center.json").toURL();
+        IOException e = assertThrows(IOException.class, () -> DownloadService.loadJSONHTML(badURL));
+        assertThat(e.getMessage(), containsString(badURL.toString()));
+        assertThat(e.getMessage(), containsString("due to UnknownHostException:"));
+    }
+
     @Test
     void testReduceFunctionWithMavenJsons() throws Exception {
         URL resource1 = DownloadServiceTest.class.getResource("hudson.tasks.Maven.MavenInstaller1.json");