[JENKINS-37189] Refactor to make more testable

- A pure unit tests will suffice

core/src/test/java/hudson/model/UpdateCenterTest.java

@@ -0,0 +1,44 @@
+package hudson.model;
+
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+public class UpdateCenterTest {
+
+    @Test
+    public void toUpdateCenterCheckUrl_http_noQuery() throws Exception {
+        assertThat(UpdateCenter.UpdateCenterConfiguration.toUpdateCenterCheckUrl(
+                "http://updates.jenkins-ci.org/update-center.json").toExternalForm(),
+                is("http://updates.jenkins-ci.org/update-center.json?uctest"));
+    }
+
+    @Test
+    public void toUpdateCenterCheckUrl_https_noQuery() throws Exception {
+        assertThat(UpdateCenter.UpdateCenterConfiguration.toUpdateCenterCheckUrl(
+                "https://updates.jenkins-ci.org/update-center.json").toExternalForm(),
+                is("https://updates.jenkins-ci.org/update-center.json?uctest"));
+    }
+
+    @Test
+    public void toUpdateCenterCheckUrl_http_query() throws Exception {
+        assertThat(UpdateCenter.UpdateCenterConfiguration.toUpdateCenterCheckUrl(
+                "http://updates.jenkins-ci.org/update-center.json?version=2.7").toExternalForm(),
+                is("http://updates.jenkins-ci.org/update-center.json?version=2.7&uctest"));
+    }
+
+    @Test
+    public void toUpdateCenterCheckUrl_https_query() throws Exception {
+        assertThat(UpdateCenter.UpdateCenterConfiguration.toUpdateCenterCheckUrl(
+                "https://updates.jenkins-ci.org/update-center.json?version=2.7").toExternalForm(),
+                is("https://updates.jenkins-ci.org/update-center.json?version=2.7&uctest"));
+    }
+
+    @Test
+    public void toUpdateCenterCheckUrl_file() throws Exception {
+        assertThat(UpdateCenter.UpdateCenterConfiguration.toUpdateCenterCheckUrl(
+                "file://./foo.jar!update-center.json").toExternalForm(),
+                is("file://./foo.jar!update-center.json"));
+    }
+}