Add a test to validate relative URLs (#363)

src/test/java/ValidRelativeUrlsTest.java

@@ -0,0 +1,90 @@
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.TestInstance.Lifecycle.PER_CLASS;
+
+import io.jenkins.plugins.designlibrary.UISample;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Stream;
+import org.htmlunit.html.DomNode;
+import org.htmlunit.html.HtmlAnchor;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.TestInstance;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+import org.jvnet.hudson.test.JenkinsRule;
+import org.jvnet.hudson.test.junit.jupiter.WithJenkins;
+
+@WithJenkins
+@TestInstance(PER_CLASS)
+class ValidRelativeUrlsTest {
+
+    private JenkinsRule jenkins;
+
+    private List<UISample> samples;
+
+    @BeforeAll
+    void beforeAll(JenkinsRule jenkins) {
+        this.jenkins = jenkins;
+        this.samples = jenkins.getInstance().getExtensionList(UISample.class);
+    }
+
+    /**
+     * Validate that relative URLs on a page actually link to a {@link UISample}
+     */
+    @ParameterizedTest
+    @MethodSource("getPages")
+    void validRelativeUrls(String url) throws Exception {
+        try (var webClient = jenkins.createWebClient().withJavaScriptEnabled(false)) {
+            // We get a bunch of spam in our logs about missing CSS, let's ignore that
+            webClient.getOptions().setPrintContentOnFailingStatusCode(false);
+            webClient.getOptions().setThrowExceptionOnFailingStatusCode(false);
+
+            List<String> validUrls =
+                    new ArrayList<>(samples.stream().map(UISample::getUrlName).toList());
+
+            var page = webClient.goTo(url);
+            var links = page.querySelectorAll(".jdl-section a");
+
+            if (links.isEmpty()) {
+                System.out.println("🤷 No URLs on: " + url);
+                return;
+            }
+
+            links.stream().filter(this::filterUrl).map(this::cleanseUrl).forEach(link -> {
+                System.out.println("🕵️ Checking URL: " + link);
+                assertThat(validUrls)
+                        .withFailMessage(() -> "'" + link + "' isn't a valid URL, it needs to be one of:\n"
+                                + String.join("\n", validUrls))
+                        .contains(link);
+            });
+        }
+    }
+
+    private Stream<String> getPages() {
+        Stream<String> homePage = Stream.of("design-library");
+        Stream<String> otherItems = samples.stream().map(e -> "design-library/" + e.getUrlName());
+        return Stream.concat(homePage, otherItems);
+    }
+
+    private boolean filterUrl(DomNode anchor) {
+        var url = ((HtmlAnchor) anchor).getHrefAttribute();
+        var response = !url.startsWith("http")
+                && !url.startsWith("#")
+                && !url.equals(".")
+                && !url.equals("..")
+                && !url.equals("twoColumn")
+                && !url.equals("oneColumn")
+                && !url.equals("fullscreen");
+
+        if (!response) {
+            System.out.println("🤫 Ignoring URL: " + url);
+        }
+
+        return response;
+    }
+
+    private String cleanseUrl(DomNode anchor) {
+        var url = ((HtmlAnchor) anchor).getHrefAttribute();
+        return url.replace("../", "");
+    }
+}