Issue 214: Support of config bundles with extra configuration files

RegexpHeader/Example2/extra-config-files.txt

@@ -0,0 +1 @@
+java.header 

extractor/src/main/java/com/example/extractor/CheckstyleExampleExtractor.java

@@ -112,6 +112,31 @@ public final class CheckstyleExampleExtractor {
      */
     private static final int BUFFER_SIZE = 1024;
 
+    /**
+     * Number of expected arguments when processing a configuration file.
+     */
+    private static final int CONFIG_FILE_ARG_COUNT = 5;
+
+    /**
+     * Index of the "--config-file" flag in the argument array.
+     */
+    private static final int CONFIG_FILE_FLAG_INDEX = 1;
+
+    /**
+     * Index of the configuration file path in the argument array.
+     */
+    private static final int CONFIG_FILE_PATH_INDEX = 2;
+
+    /**
+     * Index of the output file path in the argument array.
+     */
+    private static final int CONFIG_OUTPUT_PATH_INDEX = 3;
+
+    /**
+     * Index of the projects output path in the argument array.
+     */
+    private static final int CONFIG_PROJECTS_PATH_INDEX = 4;
+
     /**
      * Private constructor to prevent instantiation of this utility class.
      */
@@ -147,6 +172,19 @@ public static void main(final String[] args) throws Exception {
             // Output default projects list
             outputDefaultProjectsList(projectsOutputPath);
         }
+        else if (args.length == CONFIG_FILE_ARG_COUNT
+                && "--config-file".equals(args[CONFIG_FILE_FLAG_INDEX])) {
+            // New functionality: process external config file
+            final String configFilePath = args[CONFIG_FILE_PATH_INDEX];
+            final String configOutputPath = args[CONFIG_OUTPUT_PATH_INDEX];
+            final String projectsOutputPath = args[CONFIG_PROJECTS_PATH_INDEX];
+
+            // Process config file and generate output
+            processConfigFile(Paths.get(configFilePath), Paths.get(configOutputPath));
+
+            // Output default projects list
+            outputDefaultProjectsList(projectsOutputPath);
+        }
         else {
             // Functionality: process all examples
             final String checkstyleRepoPath = args[0];
@@ -162,6 +200,33 @@ public static void main(final String[] args) throws Exception {
         }
     }
 
+    /**
+     * Processes a configuration file and generates an output file.
+     *
+     * @param configFile  The path to the configuration file
+     * @param outputFile The path to the output file
+     * @throws Exception If an error occurs during processing
+     * @throws IOException If an error occurs during processing
+     */
+    public static void processConfigFile(
+            final Path configFile,
+            final Path outputFile)
+            throws Exception {
+        // Check if the config file exists
+        if (!Files.exists(configFile)) {
+            LOGGER.severe("Config file does not exist: " + configFile);
+            throw new IOException("Config file does not exist: " + configFile);
+        }
+
+        // Read the config file content
+        final String configContent = Files.readString(configFile, StandardCharsets.UTF_8);
+
+        // Write the config content to the output file
+        Files.writeString(outputFile, configContent, StandardCharsets.UTF_8);
+
+        LOGGER.info("Generated configuration at " + outputFile);
+    }
+
     /**
      * Writes the default projects list to the specified file.
      *

extractor/src/test/java/com/example/extractor/MainsLauncherTest.java

@@ -40,22 +40,20 @@
  */
 class MainsLauncherTest {
 
-    /**
-     * The base path to the Checkstyle repository.
-     */
+    /** The base path to the Checkstyle repository. */
     private static final String CHECKSTYLE_REPO_PATH = "../.ci-temp/checkstyle";
 
-    /**
-     * Base path for Checkstyle checks package used in test resource files.
-     */
+    /** Base path for Checkstyle checks package used in test resource files. */
     private static final String CHECKSTYLE_CHECKS_BASE_PATH =
             "com/puppycrawl/tools/checkstyle/checks";
 
-    /**
-     * The constant for default projects file.
-     */
+    /** The constant for default projects file. */
     private static final String DEFAULT_PROJECTS_FILE = "list-of-projects.yml";
 
+    /** Temporary folder for test files. */
+    @TempDir
+    Path temporaryFolder;
+
     /**
      * Tests the main method of CheckstyleExampleExtractor.
      * This test ensures that the main method runs without throwing any exceptions.
@@ -122,7 +120,6 @@ private String loadDefaultProjectsList() throws IOException {
 
     /**
      * Tests the getTemplateFilePathForInputFile method.
-     *
      */
     @Test
     void testGetTemplateFilePathForInputFile() throws Exception {
@@ -143,4 +140,85 @@ private String loadToString(final String filePath) throws IOException {
         final byte[] encoded = Files.readAllBytes(Paths.get(filePath));
         return new String(encoded, StandardCharsets.UTF_8);
     }
+
+    /**
+     * Tests the external config files functionality.
+     */
+    @Test
+    void testMainWithExternalConfigFiles(@TempDir final Path tempDir) throws Exception {
+        // Create the 'config' directory inside the tempDir
+        final Path configDir = tempDir.resolve("config");
+        Files.createDirectories(configDir);
+
+        // Write the java.header file inside the 'config' directory
+        final String headerFileContent = """
+        ^// Copyright \\(C\\) (\\d\\d\\d\\d -)? 2004 MyCompany$
+        ^// All rights reserved$
+            """;
+
+        final Path headerFile = configDir.resolve("java.header");
+        Files.writeString(headerFile, headerFileContent);
+
+        // Write the config.xml file with ${execution.path} - this is key for DiffTool
+        final String configXmlContent = """
+        <?xml version="1.0"?>
+        <!DOCTYPE module PUBLIC
+            "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
+            "https://checkstyle.org/dtds/configuration_1_3.dtd">
+        <module name="Checker">
+          <module name="RegexpHeader">
+            <property name="headerFile" value="${execution.path}/config/java.header"/>
+            <property name="multiLines" value="10, 13"/>
+          </module>
+        </module>
+            """;
+
+        final Path configXmlFile = tempDir.resolve("config.xml");
+        Files.writeString(configXmlFile, configXmlContent);
+
+        // Write the test input file (could be an empty Java file)
+        final String testFileContent = """
+        // Sample header content
+        // That should be matched
+
+        public class TestClass {
+            // class content
+        }
+            """;
+
+        final Path testFile = tempDir.resolve("TestClass.java");
+        Files.writeString(testFile, testFileContent);
+
+        // Define the output files for the extractor
+        final Path outputConfigFile = tempDir.resolve("output-config.xml");
+        final Path outputProjectsFile = tempDir.resolve("output-projects.yml");
+
+        // Modify the CheckstyleExampleExtractor to accept a config file
+        assertDoesNotThrow(() -> {
+            CheckstyleExampleExtractor.main(new String[]{
+                CHECKSTYLE_REPO_PATH,
+                "--config-file",
+                configXmlFile.toString(),
+                outputConfigFile.toString(),
+                outputProjectsFile.toString(),
+            });
+        });
+
+        // Verify that the output config file is created
+        assertTrue(Files.exists(outputConfigFile), "Config output file should be created");
+
+        // Load the generated config content
+        final String generatedConfigContent = Files.readString(outputConfigFile);
+
+        // Verify that the generated config includes the external file reference with execution.path
+        assertThat(generatedConfigContent)
+                .contains("<property name=\"headerFile\" "
+                        + "value=\"${execution.path}/config/java.header\"/>");
+
+        // Verify that the projects file is created and not empty
+        assertTrue(Files.exists(outputProjectsFile), "Projects output file should be created");
+        final String generatedProjectsContent = Files.readString(outputProjectsFile);
+        assertFalse(generatedProjectsContent.isEmpty(), "Projects file should not be empty");
+    }
 }
+