8262899: TestRedirectLinks fails

Backport-of: f17ea9e66b68b987b4c780b4a9f99762b8be403b

Author: Abdul Kolarkunnu

src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/toolkit/util/Extern.java

@@ -387,7 +387,7 @@ private static class Fault extends Exception {
         private static final long serialVersionUID = 0;
 
         Fault(String msg, Exception cause) {
-            super(msg, cause);
+            super(msg + (cause == null ? "" : " (" + cause + ")"), cause);
         }
     }
 

test/langtools/jdk/javadoc/doclet/testLinkOption/TestRedirectLinks.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -43,9 +43,12 @@
 import java.net.InetSocketAddress;
 import java.net.URL;
 import java.net.URLConnection;
+import java.net.UnknownHostException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.security.KeyStore;
+import java.time.Duration;
+import java.time.Instant;
 
 import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.HttpsURLConnection;
@@ -84,9 +87,31 @@ public static void main(String... args) throws Exception {
      */
     @Test
     public void testRedirects() throws Exception {
-        // first, test to see if access to external URLs is available
+        // This test relies on access to an external resource, which may or may not be
+        // reliably available, depending on the host system configuration and other
+        // networking issues. Therefore, it is disabled by default, unless the system
+        // property "javadoc.dev" is set "true".
+        String property = "javadoc.dev";
+        if (!Boolean.getBoolean(property)) {
+            out.println("Test case disabled by default; "
+                    + "set system property \"" + property + "\" to true to enable it.");
+            return;
+        }
+
+        // test to see if access to external URLs is available, and that the URL uses a redirect
+
         URL testURL = new URL("http://docs.oracle.com/en/java/javase/11/docs/api/element-list");
+        String testURLHost = testURL.getHost();
+        try {
+            InetAddress testAddr = InetAddress.getByName(testURLHost);
+            out.println("Found " + testURLHost + ": " + testAddr);
+        } catch (UnknownHostException e) {
+            out.println("Setup failed (" + testURLHost + " not found); this test skipped");
+            return;
+        }
+
         boolean haveRedirectURL = false;
+        Instant start = Instant.now();
         try {
             URLConnection conn = testURL.openConnection();
             conn.connect();
@@ -107,10 +132,12 @@ public void testRedirects() throws Exception {
             }
         } catch (Exception e) {
             out.println("Exception occurred: " + e);
+            Instant now = Instant.now();
+            out.println("Attempt took " + Duration.between(start, now).toSeconds() + " seconds");
         }
 
         if (!haveRedirectURL) {
-            out.println("Setup failed; this test skipped");
+            out.println("Setup failed (no redirect URL); this test skipped");
             return;
         }
 
@@ -119,6 +146,7 @@ public void testRedirects() throws Exception {
         javadoc("-d", outRedirect,
                 "-sourcepath", testSrc,
                 "-link", apiURL,
+                "-Xdoclint:none",
                 "pkg");
         checkExit(Exit.OK);
         checkOutput("pkg/B.html", true,
@@ -157,16 +185,19 @@ public void testWithServers() throws Exception {
         new JavacTask(tb)
                 .outdir(libModules)
                 .options("--module-source-path", libSrc.toString(),
-                        "--module", "mA,mB")
+                        "--module", "mA,mB",
+                        "-Xdoclint:none")
                 .run()
                 .writeAll();
 
         javadoc("-d", libApi.toString(),
                 "--module-source-path", libSrc.toString(),
-                "--module", "mA,mB" );
+                "--module", "mA,mB",
+                "-Xdoclint:none" );
 
         // start web servers
-        InetAddress localHost = InetAddress.getLocalHost();
+        // use loopback address to avoid any issues if proxy is in use
+        InetAddress localHost = InetAddress.getLoopbackAddress();
         try {
             oldServer = HttpServer.create(new InetSocketAddress(localHost, 0), 0);
             String oldURL = "http:/" + oldServer.getAddress();
@@ -201,7 +232,8 @@ public void testWithServers() throws Exception {
                         "--module-source-path", src.toString(),
                         "--module-path", libModules.toString(),
                         "-link", "http:/" + oldServer.getAddress(),
-                        "--module", "mC" );
+                        "--module", "mC",
+                        "-Xdoclint:none");
 
             } finally {
                 HttpsURLConnection.setDefaultHostnameVerifier(prevHostNameVerifier);