Test the retry of downloadFile

src/test/java/io/jenkins/plugins/httpclient/RobustHTTPClientIntegrationTest.java

@@ -21,7 +21,6 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
-
 package io.jenkins.plugins.httpclient;
 
 import static org.hamcrest.MatcherAssert.*;
@@ -30,6 +29,7 @@
 
 import hudson.AbortException;
 import hudson.model.TaskListener;
+import hudson.model.UnprotectedRootAction;
 import java.io.File;
 import java.io.IOException;
 import java.net.URL;
@@ -42,6 +42,9 @@
 import org.junit.Test;
 import org.junit.rules.TemporaryFolder;
 import org.jvnet.hudson.test.JenkinsRule;
+import org.jvnet.hudson.test.TestExtension;
+import org.kohsuke.stapler.HttpResponse;
+import org.kohsuke.stapler.HttpResponses;
 
 public class RobustHTTPClientIntegrationTest {
 
@@ -66,16 +69,37 @@ public void testDownloadFile() throws Exception {
         assertThat(Files.readString(f.toPath()), containsString("<title>Dashboard [Jenkins]</title>"));
     }
 
+    /**
+     * Wait no more than TIMEOUT seconds for response
+     */
+    private static final int TIMEOUT = 2;
+
     @Test
     public void testDownloadFileWithTimeoutException() throws Exception {
         client.setStopAfterAttemptNumber(1);
-        client.setTimeout(50, TimeUnit.MICROSECONDS);
+        client.setTimeout(TIMEOUT, TimeUnit.SECONDS);
+        URL hangingURL = new URL(j.getURL().toString() + "intentionally-hangs-always");
         final IOException e = assertThrows(IOException.class, () -> {
-            client.downloadFile(f, j.getURL(), TaskListener.NULL);
+            client.downloadFile(f, hangingURL, TaskListener.NULL);
         });
         assertThat(e.getCause(), isA(TimeoutException.class));
     }
 
+    @Test
+    public void testDownloadFileWithRetry() throws Exception {
+        // Try up to three times, should succeed on second try
+        client.setStopAfterAttemptNumber(3);
+        // Wait 213 milliseconds before retry (no need for a long wait)
+        client.setWaitMultiplier(213, TimeUnit.MILLISECONDS);
+        // Wait no more than 3x the TIMEOUT between retries (upper bound)
+        client.setWaitMaximum(TIMEOUT * 3, TimeUnit.SECONDS);
+        // Retry if no response in TIMEOUT seconds
+        client.setTimeout(TIMEOUT, TimeUnit.SECONDS);
+        URL hangsOnceURL = new URL(j.getURL().toString() + "intentionally-hangs-once");
+        client.downloadFile(f, hangsOnceURL, TaskListener.NULL);
+        assertThat(Files.readString(f.toPath()), containsString("a-dubious-response-from-hangs-once"));
+    }
+
     @Test
     public void testDownloadFileFromNonExistentLocation() throws Exception {
         URL badURL = new URL(j.getURL().toString() + "/page/does/not/exist");
@@ -94,4 +118,68 @@ public void testDownloadFileStopAfterOneAttempt() throws Exception {
         });
         assertThat(e.getMessage(), containsString("Failed to download "));
     }
+
+    @TestExtension
+    public static class IntentionallyHangsAlwaysAction implements UnprotectedRootAction {
+
+        @Override
+        public String getIconFileName() {
+            return null;
+        }
+
+        @Override
+        public String getDisplayName() {
+            return null;
+        }
+
+        @Override
+        public String getUrlName() {
+            return "intentionally-hangs-always";
+        }
+
+        public HttpResponse doIndex() {
+            try {
+                // Sleep 3x longer than the timeout
+                Thread.sleep(TIMEOUT * 3L * 1000L);
+            } catch (InterruptedException ie) {
+                // Ignore the exception
+            }
+            return HttpResponses.text("a-dubious-response-from-hangs-always");
+        }
+    }
+
+    @TestExtension
+    public static class IntentionallyHangsOnceAction implements UnprotectedRootAction {
+
+        private int requestCount = 0;
+
+        @Override
+        public String getIconFileName() {
+            return null;
+        }
+
+        @Override
+        public String getDisplayName() {
+            return null;
+        }
+
+        @Override
+        public String getUrlName() {
+            return "intentionally-hangs-once";
+        }
+
+        public HttpResponse doIndex() {
+            requestCount++;
+            if (requestCount <= 1) {
+                /* Wait 3x longer than timeout on first request */
+                try {
+                    // Sleep 3x longer than the timeout
+                    Thread.sleep(TIMEOUT * 3L * 1000L);
+                } catch (InterruptedException ie) {
+                    // Ignore the exception
+                }
+            }
+            return HttpResponses.text("a-dubious-response-from-hangs-once");
+        }
+    }
 }