Add failing test that reproduces JENKINS-48604

test/src/test/java/jenkins/install/LoadDetachedPluginsTest.java

@@ -26,10 +26,12 @@ package jenkins.install;
 
 import hudson.ClassicPluginStrategy;
 import hudson.ClassicPluginStrategy.DetachedPlugin;
+import hudson.Plugin;
 import hudson.PluginManager;
 import hudson.PluginManagerUtil;
 import hudson.PluginWrapper;
 import hudson.util.VersionNumber;
+import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
@@ -44,6 +46,7 @@ import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.not;
+import static org.hamcrest.Matchers.notNullValue;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 
@@ -81,6 +84,25 @@ public class LoadDetachedPluginsTest {
         });
     }
 
+    @Issue("JENKINS-48604")
+    @Test
+    @LocalData
+    public void upgradeFromJenkins2WithDependency() {
+        VersionNumber since = new VersionNumber("2.0");
+        rr.then((JenkinsRule r) -> {
+            List<DetachedPlugin> detachedPlugins = ClassicPluginStrategy.getDetachedPlugins(since);
+            assertThat("Plugins have been detached since the pre-upgrade version",
+                    detachedPlugins.size(), greaterThan(1));
+            assertThat("Plugins detached between the pre-upgrade version and the current version should be installed",
+                    getInstalledDetachedPlugins(r, detachedPlugins).size(), equalTo(detachedPlugins.size()));
+            Plugin scriptSecurity = r.jenkins.getPlugin("script-security");
+            assertThat("Script-security should be installed", scriptSecurity, notNullValue());
+            assertThat("Dependencies of detached plugins should not be downgraded",
+                    scriptSecurity.getWrapper().getVersionNumber(), greaterThan(new VersionNumber("1.18.1")));
+            assertNoFailedPlugins(r);
+        });
+    }
+
     @Test
     public void newInstallation() {
         rr.then(r -> {