fix: Also load default JAR resources for DevModeInitializer (#9823)

Fixes #9802
# Conflicts:
#	flow-server/src/main/java/com/vaadin/flow/server/startup/DevModeInitializer.java
#	flow-server/src/test/java/com/vaadin/flow/server/startup/DevModeInitializerTest.java

flow-server/src/main/java/com/vaadin/flow/server/Constants.java

@@ -300,6 +300,11 @@ public final class Constants implements Serializable {
      */
     public static final String RESOURCES_JAR_DEFAULT = "META-INF/resources/";
 
+    /**
+     * Location for the theme resources in jar files.
+     */
+    public static final String RESOURCES_THEME_JAR_DEFAULT = RESOURCES_JAR_DEFAULT + APPLICATION_THEME_ROOT + "/";
+
     /**
      * @deprecated Use
      *             {@link InitParameters#SERVLET_PARAMETER_DEVMODE_WEBPACK_TIMEOUT}

flow-server/src/main/java/com/vaadin/flow/server/startup/DevModeInitializer.java

@@ -87,7 +87,6 @@
 
 import elemental.json.Json;
 import elemental.json.JsonObject;
-
 import static com.vaadin.flow.server.Constants.PACKAGE_JSON;
 import static com.vaadin.flow.server.InitParameters.SERVLET_PARAMETER_DEVMODE_OPTIMIZE_BUNDLE;
 import static com.vaadin.flow.server.frontend.FrontendUtils.DEFAULT_FRONTEND_DIR;
@@ -173,6 +172,11 @@ private static Set<String> calculateApplicableClassNames() {
     private static final Pattern DIR_REGEX_FRONTEND_DEFAULT = Pattern.compile(
             "^(?:file:0)?(.+)" + Constants.RESOURCES_FRONTEND_DEFAULT + "/?$");
 
+    // allow trailing slash
+    private static final Pattern DIR_REGEX_RESOURCES_JAR_DEFAULT = Pattern
+            .compile("^(?:file:0)?(.+)" + Constants.RESOURCES_THEME_JAR_DEFAULT
+                    + "/?$");
+
     // allow trailing slash
     private static final Pattern DIR_REGEX_COMPATIBILITY_FRONTEND_DEFAULT = Pattern
             .compile("^(?:file:)?(.+)"
@@ -407,8 +411,8 @@ private static String getBaseDirectoryFallback() {
 
     /*
      * This method returns all folders of jar files having files in the
-     * META-INF/resources/frontend folder. We don't use URLClassLoader because
-     * will fail in Java 9+
+     * META-INF/resources/frontend and META-INF/resources/themes folder.
+     * We don't use URLClassLoader because will fail in Java 9+
      */
     static Set<File> getFrontendLocationsFromClassloader(
             ClassLoader classLoader) throws ServletException {
@@ -417,6 +421,8 @@ static Set<File> getFrontendLocationsFromClassloader(
                 Constants.RESOURCES_FRONTEND_DEFAULT));
         frontendFiles.addAll(getFrontendLocationsFromClassloader(classLoader,
                 Constants.COMPATIBILITY_RESOURCES_FRONTEND_DEFAULT));
+        frontendFiles.addAll(getFrontendLocationsFromClassloader(classLoader,
+            Constants.RESOURCES_THEME_JAR_DEFAULT));
         return frontendFiles;
     }
 
@@ -458,6 +464,8 @@ private static Set<File> getFrontendLocationsFromClassloader(
                 Matcher zipProtocolJarMatcher = ZIP_PROTOCOL_JAR_FILE_REGEX
                         .matcher(path);
                 Matcher dirMatcher = DIR_REGEX_FRONTEND_DEFAULT.matcher(path);
+                Matcher dirResourcesMatcher = DIR_REGEX_RESOURCES_JAR_DEFAULT
+                        .matcher(path);
                 Matcher dirCompatibilityMatcher = DIR_REGEX_COMPATIBILITY_FRONTEND_DEFAULT
                         .matcher(path);
                 Matcher jarVfsMatcher = VFS_FILE_REGEX.matcher(urlString);
@@ -479,6 +487,8 @@ private static Set<File> getFrontendLocationsFromClassloader(
                     frontendFiles.add(new File(zipProtocolJarMatcher.group(1)));
                 } else if (dirMatcher.find()) {
                     frontendFiles.add(new File(dirMatcher.group(1)));
+                } else if (dirResourcesMatcher.find()) {
+                    frontendFiles.add(new File(dirResourcesMatcher.group(1)));
                 } else if (dirCompatibilityMatcher.find()) {
                     frontendFiles
                             .add(new File(dirCompatibilityMatcher.group(1)));

flow-server/src/test/java/com/vaadin/flow/server/startup/DevModeInitializerTest.java

@@ -39,6 +39,7 @@
 import com.vaadin.flow.server.frontend.FallbackChunk;
 import com.vaadin.flow.server.frontend.FrontendUtils;
 
+import static com.vaadin.flow.server.Constants.RESOURCES_THEME_JAR_DEFAULT;
 import static com.vaadin.flow.server.InitParameters.SERVLET_PARAMETER_COMPATIBILITY_MODE;
 import static com.vaadin.flow.server.InitParameters.SERVLET_PARAMETER_DEVMODE_OPTIMIZE_BUNDLE;
 import static org.junit.Assert.assertEquals;
@@ -119,6 +120,14 @@ public void loadingJars_useModernResourcesFolder_allFilesExist()
         loadingJars_allFilesExist(Constants.RESOURCES_FRONTEND_DEFAULT);
     }
 
+    @Test
+    public void loadingJars_useResourcesThemesFolder_allFilesExist()
+            throws IOException, ServletException {
+        loadingJarsWithProtocol_allFilesExist(RESOURCES_THEME_JAR_DEFAULT,
+            "src/test/resources/jar-with-themes-resources.jar!/META-INF/resources/themes",
+            this::jarUrlBuilder);
+    }
+
     @Test
     public void loadingZipProtocolJars_useModernResourcesFolder_allFilesExist()
             throws IOException, ServletException {
@@ -140,6 +149,13 @@ public void loadingFsResources_useModernResourcesFolder_allFilesExist()
                 Constants.RESOURCES_FRONTEND_DEFAULT);
     }
 
+    @Test
+    public void loadingFsResources_useResourcesThemesFolder_allFilesExist()
+            throws IOException, ServletException {
+        loadingFsResources_allFilesExist("/dir-with-theme-resources/",
+                RESOURCES_THEME_JAR_DEFAULT);
+    }
+
     @Test
     public void loadingFsResources_useObsoleteResourcesFolder_allFilesExist()
             throws IOException, ServletException {
@@ -389,13 +405,15 @@ public void onStartup_fallbackBaseDirIsGradleProjectDirectory_isAccepted()
 
     private void loadingJars_allFilesExist(String resourcesFolder)
             throws IOException, ServletException {
-        loadingJarsWithProtocol_allFilesExist(resourcesFolder, s -> {
-            try {
-                return new URL("jar:" + s);
-            } catch (MalformedURLException e) {
-                throw new RuntimeException(e);
-            }
-        });
+        loadingJarsWithProtocol_allFilesExist(resourcesFolder, this::jarUrlBuilder);
+    }
+
+    private URL jarUrlBuilder(String url) {
+        try {
+            return new URL("jar:" + url);
+        } catch (MalformedURLException e) {
+            throw new RuntimeException(e);
+        }
     }
 
     private void loadingZipProtocolJars_allFilesExist(String resourcesFolder)
@@ -421,30 +439,38 @@ protected URLConnection openConnection(URL u) throws IOException {
     private void loadingJarsWithProtocol_allFilesExist(String resourcesFolder,
             Function<String, URL> urlBuilder)
             throws IOException, ServletException {
+        loadingJarsWithProtocol_allFilesExist(resourcesFolder,
+                "src/test/resources/with%20space/jar-with-frontend-resources.jar!/META-INF/resources/frontend",
+                urlBuilder);
+    }
+
+    private void loadingJarsWithProtocol_allFilesExist(String resourcesFolder, String jarContent,
+                                                       Function<String, URL> urlBuilder)
+        throws IOException, ServletException {
         // Create jar urls with the given urlBuilder for test
         String urlPath = this.getClass().getResource("/").toString()
-                .replace("target/test-classes/", "")
-                + "src/test/resources/with%20space/jar-with-frontend-resources.jar!/META-INF/resources/frontend";
+            .replace("target/test-classes/", "")
+            + jarContent;
         URL jar = urlBuilder.apply(urlPath);
         List<URL> urls = new ArrayList<>();
         urls.add(jar);
 
         // Create mock loader with the single jar to be found
         ClassLoader classLoader = Mockito.mock(ClassLoader.class);
         Mockito.when(classLoader.getResources(resourcesFolder))
-                .thenReturn(Collections.enumeration(urls));
+            .thenReturn(Collections.enumeration(urls));
 
         // load jars from classloader
         List<File> jarFilesFromClassloader = new ArrayList<>(DevModeInitializer
-                .getFrontendLocationsFromClassloader(classLoader));
+            .getFrontendLocationsFromClassloader(classLoader));
 
         // Assert that jar was found and accepted
         assertEquals("One jar should have been found and added as a File", 1,
-                jarFilesFromClassloader.size());
+            jarFilesFromClassloader.size());
         // Assert that the file can be found from the filesystem by the given
         // path.
         assertTrue("File in path 'with space' doesn't load from given path",
-                jarFilesFromClassloader.get(0).exists());
+            jarFilesFromClassloader.get(0).exists());
     }
 
     private void loadingFsResources_allFilesExist(String resourcesRoot,

flow-server/src/test/resources/dir-with-theme-resources/META-INF/resources/themes/reusable-theme/theme.json

@@ -0,0 +1 @@
+{}