PluginManager#whichPlugin does not work for JenkinsRule (#6982)

Co-authored-by: Jesse Glick <[email protected]>

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

@@ -79,7 +79,10 @@
 import java.net.URLClassLoader;
 import java.net.URLConnection;
 import java.nio.file.Files;
+import java.nio.file.InvalidPathException;
+import java.nio.file.Paths;
 import java.nio.file.attribute.FileTime;
+import java.security.CodeSource;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -1324,6 +1327,39 @@ public PluginWrapper whichPlugin(Class c) {
                 oneAndOnly = p;
             }
         }
+        if (oneAndOnly == null && Main.isUnitTest) {
+            // compare jenkins.security.ClassFilterImpl
+            CodeSource cs = c.getProtectionDomain().getCodeSource();
+            if (cs != null) {
+                URL loc = cs.getLocation();
+                if (loc != null) {
+                    if ("file".equals(loc.getProtocol())) {
+                        File file;
+                        try {
+                            file = Paths.get(loc.toURI()).toFile();
+                        } catch (InvalidPathException | URISyntaxException e) {
+                            LOGGER.log(Level.WARNING, "could not inspect " + loc, e);
+                            return null;
+                        }
+                        if (file.isFile()) { // ignore directories
+                            try (JarFile jf = new JarFile(file)) {
+                                Manifest mf = jf.getManifest();
+                                if (mf != null) {
+                                    java.util.jar.Attributes attr = mf.getMainAttributes();
+                                    if (attr.getValue("Plugin-Version") != null) {
+                                        String shortName = attr.getValue("Short-Name");
+                                        LOGGER.fine(() -> "found " + shortName + " for " + c);
+                                        return getPlugin(shortName);
+                                    }
+                                }
+                            } catch (IOException e) {
+                                LOGGER.log(Level.WARNING, "could not inspect " + loc, e);
+                            }
+                        }
+                    }
+                }
+            }
+        }
         return oneAndOnly;
     }
 

test/src/test/java/hudson/PluginManagerWhichTest.java

@@ -0,0 +1,45 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2022 CloudBees, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package hudson;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+import com.cloudbees.hudson.plugins.folder.Folder;
+import org.junit.Rule;
+import org.junit.Test;
+import org.jvnet.hudson.test.JenkinsRule;
+
+public class PluginManagerWhichTest {
+
+    @Rule public JenkinsRule r = new JenkinsRule();
+
+    @Test
+    public void whichPlugin() throws Exception {
+        PluginWrapper expected = r.getPluginManager().getPlugin("cloudbees-folder");
+        assertNotNull(expected);
+        assertEquals(expected, r.getPluginManager().whichPlugin(Folder.class));
+    }
+}