Validate simple-theme demo with the integrations framework (#1123)

demos/simple-theme-plugin/README.md

@@ -1,4 +1,6 @@
-# configure simple-theme-plugin plugin
+# Configure simple-theme-plugin plugin
+
+Basic configuration of the [Simple Theme plugin](https://plugins.jenkins.io/simple-theme-plugin)
 
 ## sample configuration
 

integrations/pom.xml

@@ -209,6 +209,13 @@
       <scope>test</scope>
     </dependency>
 
+    <dependency>
+      <groupId>org.jenkins-ci.plugins</groupId>
+      <artifactId>simple-theme-plugin</artifactId>
+      <version>0.5</version>
+      <scope>test</scope>
+    </dependency>
+
     <dependency>
       <groupId>org.jenkins-ci.plugins.workflow</groupId>
       <artifactId>workflow-cps-global-lib</artifactId>

integrations/src/test/java/io/jenkins/plugins/casc/SimpleThemeTest.java

@@ -0,0 +1,28 @@
+package io.jenkins.plugins.casc;
+
+import hudson.ExtensionList;
+import io.jenkins.plugins.casc.misc.ConfiguredWithReadme;
+import io.jenkins.plugins.casc.misc.JenkinsConfiguredWithReadmeRule;
+import org.codefirst.SimpleThemeDecorator;
+import org.junit.Rule;
+import org.junit.Test;
+
+import static org.junit.Assert.assertNotNull;
+
+/**
+ * @author v1v (Victor Martinez)
+ */
+public class SimpleThemeTest {
+
+    @Rule
+    public JenkinsConfiguredWithReadmeRule j = new JenkinsConfiguredWithReadmeRule();
+
+    @Test
+    @ConfiguredWithReadme("simple-theme-plugin/README.md")
+    public void configure_simple_theme() throws Exception {
+        // Already tested within the plugin itself, let's run some basic tests.
+        // https://github.com/jenkinsci/simple-theme-plugin/blob/master/src/test/java/org/jenkinsci/plugins/simpletheme/ConfigurationAsCodeTest.java
+        SimpleThemeDecorator decorator = ExtensionList.lookupSingleton(SimpleThemeDecorator.class);
+        assertNotNull(decorator);
+    }
+}