From 2f51583c8b890cbe9bd7aa5a093e5ec2d53cd4a5 Mon Sep 17 00:00:00 2001
From: Wadeck Follonier <Wadeck@users.noreply.github.com>
Date: Fri, 7 Feb 2020 14:40:08 +0100
Subject: [PATCH] [JENKINS-60867] Prevent creation of duplicated SetupWizard
 singleton instances on Jenkins startup (#4456)

* [JENKINS-60867] Blank page after SetupWizard: root cause

* Correct a test that was a bit too greedy
---
 core/src/main/java/jenkins/model/Jenkins.java       |  2 +-
 test/src/test/java/jenkins/ExtensionFilterTest.java | 13 ++++++++++---
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/core/src/main/java/jenkins/model/Jenkins.java b/core/src/main/java/jenkins/model/Jenkins.java
index dc7342bf8e..b7a51f00ef 100644
--- a/core/src/main/java/jenkins/model/Jenkins.java
+++ b/core/src/main/java/jenkins/model/Jenkins.java
@@ -3292,7 +3292,7 @@ public class Jenkins extends AbstractCIBase implements DirectlyModifiableTopLeve
                 for (Action a : getExtensionList(RootAction.class))
                     if (!actions.contains(a)) actions.add(a);
 
-                setupWizard = new SetupWizard();
+                setupWizard = ExtensionList.lookupSingleton(SetupWizard.class);
                 getInstallState().initializeState();
             }
         });
diff --git a/test/src/test/java/jenkins/ExtensionFilterTest.java b/test/src/test/java/jenkins/ExtensionFilterTest.java
index 54ae39b750..abc0a66b6a 100644
--- a/test/src/test/java/jenkins/ExtensionFilterTest.java
+++ b/test/src/test/java/jenkins/ExtensionFilterTest.java
@@ -1,10 +1,14 @@
 package jenkins;
 
+import static org.hamcrest.Matchers.hasSize;
+import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 
 import hudson.ExtensionComponent;
 import hudson.console.ConsoleAnnotatorFactory;
 import hudson.model.PageDecorator;
+import jenkins.install.SetupWizard;
+import org.hamcrest.Matchers;
 import org.junit.Rule;
 import org.junit.Test;
 import org.jvnet.hudson.test.JenkinsRule;
@@ -20,7 +24,7 @@ public class ExtensionFilterTest {
 
     @Test
     public void filter() {
-        assertTrue(PageDecorator.all().isEmpty());
+        assertThat(PageDecorator.all(), hasSize(1));
         assertTrue(ConsoleAnnotatorFactory.all().isEmpty());
     }
 
@@ -28,10 +32,13 @@ public class ExtensionFilterTest {
     public static class Impl extends ExtensionFilter {
         @Override
         public <T> boolean allows(Class<T> type, ExtensionComponent<T> component) {
-            if (type==ConsoleAnnotatorFactory.class)
+            if (type == ConsoleAnnotatorFactory.class) {
                 return false;
-            if (component.isDescriptorOf(PageDecorator.class))
+            }
+            // SetupWizard is required during startup
+            if (component.isDescriptorOf(PageDecorator.class) && !component.isDescriptorOf(SetupWizard.class)) {
                 return false;
+            }
             return true;
         }
     }