Issue checkstyle#3530: allowed ant to override and swap checker

src/main/java/com/puppycrawl/tools/checkstyle/ant/CheckstyleAntTask.java

@@ -46,13 +46,15 @@
 import com.google.common.io.Closeables;
 import com.puppycrawl.tools.checkstyle.Checker;
 import com.puppycrawl.tools.checkstyle.ConfigurationLoader;
-import com.puppycrawl.tools.checkstyle.DefaultContext;
 import com.puppycrawl.tools.checkstyle.DefaultLogger;
+import com.puppycrawl.tools.checkstyle.ModuleFactory;
+import com.puppycrawl.tools.checkstyle.PackageObjectFactory;
 import com.puppycrawl.tools.checkstyle.PropertiesExpander;
 import com.puppycrawl.tools.checkstyle.XMLLogger;
 import com.puppycrawl.tools.checkstyle.api.AuditListener;
 import com.puppycrawl.tools.checkstyle.api.CheckstyleException;
 import com.puppycrawl.tools.checkstyle.api.Configuration;
+import com.puppycrawl.tools.checkstyle.api.RootModule;
 import com.puppycrawl.tools.checkstyle.api.SeverityLevel;
 import com.puppycrawl.tools.checkstyle.api.SeverityLevelCounter;
 
@@ -262,7 +264,7 @@ public void setOmitIgnoredModules(boolean omit) {
     }
 
     ////////////////////////////////////////////////////////////////////////////
-    // Setters for Checker configuration attributes
+    // Setters for Root Module's configuration attributes
     ////////////////////////////////////////////////////////////////////////////
 
     /**
@@ -316,45 +318,45 @@ public void execute() {
      * @param checkstyleVersion Checkstyle compile version.
      */
     private void realExecute(String checkstyleVersion) {
-        // Create the checker
-        Checker checker = null;
+        // Create the root module
+        RootModule rootModule = null;
         try {
-            checker = createChecker();
+            rootModule = createRootModule();
 
             // setup the listeners
             final AuditListener[] listeners = getListeners();
             for (AuditListener element : listeners) {
-                checker.addListener(element);
+                rootModule.addListener(element);
             }
             final SeverityLevelCounter warningCounter =
                 new SeverityLevelCounter(SeverityLevel.WARNING);
-            checker.addListener(warningCounter);
+            rootModule.addListener(warningCounter);
 
-            processFiles(checker, warningCounter, checkstyleVersion);
+            processFiles(rootModule, warningCounter, checkstyleVersion);
         }
         finally {
-            destroyChecker(checker);
+            destroyRootModule(rootModule);
         }
     }
 
     /**
-     * Destroy Checker. This method exists only due to bug in cobertura library
+     * Destroy root module. This method exists only due to bug in cobertura library
      * https://github.com/cobertura/cobertura/issues/170
-     * @param checker Checker that was used to process files
+     * @param rootModule Root module that was used to process files
      */
-    private static void destroyChecker(Checker checker) {
-        if (checker != null) {
-            checker.destroy();
+    private static void destroyRootModule(RootModule rootModule) {
+        if (rootModule != null) {
+            rootModule.destroy();
         }
     }
 
     /**
-     * Scans and processes files by means given checker.
-     * @param checker Checker to process files
-     * @param warningCounter Checker's counter of warnings
+     * Scans and processes files by means given root module.
+     * @param rootModule Root module to process files
+     * @param warningCounter Root Module's counter of warnings
      * @param checkstyleVersion Checkstyle compile version
      */
-    private void processFiles(Checker checker, final SeverityLevelCounter warningCounter,
+    private void processFiles(RootModule rootModule, final SeverityLevelCounter warningCounter,
             final String checkstyleVersion) {
         final long startTime = System.currentTimeMillis();
         final List<File> files = scanFileSets();
@@ -370,7 +372,7 @@ private void processFiles(Checker checker, final SeverityLevelCounter warningCou
 
         try {
             final long processingStartTime = System.currentTimeMillis();
-            numErrs = checker.process(files);
+            numErrs = rootModule.process(files);
             final long processingEndTime = System.currentTimeMillis();
             log("To process the files took " + (processingEndTime - processingStartTime)
                 + TIME_SUFFIX, Project.MSG_VERBOSE);
@@ -397,11 +399,11 @@ private void processFiles(Checker checker, final SeverityLevelCounter warningCou
     }
 
     /**
-     * Creates new instance of {@code Checker}.
-     * @return new instance of {@code Checker}
+     * Creates new instance of the root module.
+     * @return new instance of the root module
      */
-    private Checker createChecker() {
-        final Checker checker;
+    private RootModule createRootModule() {
+        final RootModule rootModule;
         try {
             final Properties props = createOverridingProperties();
             final Configuration config =
@@ -410,24 +412,29 @@ private Checker createChecker() {
                     new PropertiesExpander(props),
                     omitIgnoredModules);
 
-            final DefaultContext context = new DefaultContext();
-            final ClassLoader loader = new AntClassLoader(getProject(),
-                    classpath);
-            context.add("classloader", loader);
-
             final ClassLoader moduleClassLoader =
                 Checker.class.getClassLoader();
-            context.add("moduleClassLoader", moduleClassLoader);
 
-            checker = new Checker();
-            checker.contextualize(context);
-            checker.configure(config);
+            final ModuleFactory factory = new PackageObjectFactory(
+                    Checker.class.getPackage().getName() + ".", moduleClassLoader);
+
+            rootModule = (RootModule) factory.createModule(config.getName());
+            rootModule.setModuleClassLoader(moduleClassLoader);
+
+            if (rootModule instanceof Checker) {
+                final ClassLoader loader = new AntClassLoader(getProject(),
+                        classpath);
+
+                ((Checker) rootModule).setClassLoader(loader);
+            }
+
+            rootModule.configure(config);
         }
         catch (final CheckstyleException ex) {
-            throw new BuildException(String.format(Locale.ROOT, "Unable to create a Checker: "
+            throw new BuildException(String.format(Locale.ROOT, "Unable to create Root Module: "
                     + "configLocation {%s}, classpath {%s}.", configLocation, classpath), ex);
         }
-        return checker;
+        return rootModule;
     }
 
     /**

src/test/java/com/puppycrawl/tools/checkstyle/MainTest.java

@@ -802,6 +802,8 @@ public void testExcludeDirectoryNotMatch() throws Exception {
 
     @Test
     public void testCustomRootModule() throws Exception {
+        TestRootModuleChecker.reset();
+
         exit.checkAssertionAfterwards(() -> {
             assertEquals("", systemOut.getLog());
             assertEquals("", systemErr.getLog());

src/test/java/com/puppycrawl/tools/checkstyle/TestRootModuleChecker.java

@@ -59,4 +59,8 @@ public void setModuleClassLoader(ClassLoader moduleClassLoader) {
     public static boolean isProcessed() {
         return processed;
     }
+
+    public static void reset() {
+        processed = false;
+    }
 }

src/test/java/com/puppycrawl/tools/checkstyle/ant/CheckstyleAntTaskTest.java

@@ -42,19 +42,25 @@
 
 import com.puppycrawl.tools.checkstyle.BaseCheckTestSupport;
 import com.puppycrawl.tools.checkstyle.DefaultLogger;
+import com.puppycrawl.tools.checkstyle.TestRootModuleChecker;
 import com.puppycrawl.tools.checkstyle.XMLLogger;
 
 public class CheckstyleAntTaskTest extends BaseCheckTestSupport {
 
     private static final String FLAWLESS_INPUT = "ant/InputCheckstyleAntTaskFlawless.java";
     private static final String VIOLATED_INPUT = "ant/InputCheckstyleAntTaskError.java";
     private static final String CONFIG_FILE = "ant/ant_task_test_checks.xml";
+    private static final String CUSTOM_ROOT_CONFIG_FILE = "config-custom-root-module.xml";
     private static final String NOT_EXISTING_FILE = "target/not_existing.xml";
     private static final String FAILURE_PROPERTY_VALUE = "myValue";
 
     private CheckstyleAntTask getCheckstyleAntTask() throws IOException {
+        return getCheckstyleAntTask(CONFIG_FILE);
+    }
+
+    private CheckstyleAntTask getCheckstyleAntTask(String configFile) throws IOException {
         final CheckstyleAntTask antTask = new CheckstyleAntTask();
-        antTask.setConfig(new File(getPath(CONFIG_FILE)));
+        antTask.setConfig(new File(getPath(configFile)));
         antTask.setProject(new Project());
         return antTask;
     }
@@ -66,6 +72,17 @@ public final void testDefaultFlawless() throws IOException {
         antTask.execute();
     }
 
+    @Test
+    public final void testCustomRootModule() throws IOException {
+        TestRootModuleChecker.reset();
+
+        final CheckstyleAntTask antTask = getCheckstyleAntTask(CUSTOM_ROOT_CONFIG_FILE);
+        antTask.setFile(new File(getPath(FLAWLESS_INPUT)));
+        antTask.execute();
+
+        assertTrue(TestRootModuleChecker.isProcessed());
+    }
+
     @Test
     public final void testFileSet() throws IOException {
         final CheckstyleAntTask antTask = getCheckstyleAntTask();
@@ -100,7 +117,7 @@ public final void testNonExistingConfig() throws IOException {
             fail("Exception is expected");
         }
         catch (BuildException ex) {
-            assertTrue(ex.getMessage().startsWith("Unable to create a Checker: configLocation"));
+            assertTrue(ex.getMessage().startsWith("Unable to create Root Module: configLocation"));
         }
     }
 
@@ -115,7 +132,7 @@ public final void testEmptyConfigFile() throws IOException {
             fail("Exception is expected");
         }
         catch (BuildException ex) {
-            assertTrue(ex.getMessage().startsWith("Unable to create a Checker: configLocation"));
+            assertTrue(ex.getMessage().startsWith("Unable to create Root Module: configLocation"));
         }
     }