Issue checkstyle#4916: Adding ability to force load

src/main/java/com/puppycrawl/tools/checkstyle/Checker.java

@@ -133,6 +133,9 @@ public class Checker extends AutomaticBean implements MessageDispatcher, RootMod
     /** Controls whether exceptions should halt execution or not. */
     private boolean haltOnException = true;
 
+    /** If true old style force loading will be used. */
+    private boolean forceLoad;
+
     /**
      * Creates a new {@code Checker} instance.
      * The instance needs to be contextualized and configured.
@@ -427,7 +430,7 @@ public void finishLocalSetup() throws CheckstyleException {
             final Set<String> packageNames = PackageNamesLoader
                     .getPackageNames(moduleClassLoader);
             moduleFactory = new PackageObjectFactory(packageNames,
-                    moduleClassLoader);
+                    moduleClassLoader, forceLoad);
         }
 
         final DefaultContext context = new DefaultContext();
@@ -614,6 +617,14 @@ public void setHaltOnException(boolean haltOnException) {
         this.haltOnException = haltOnException;
     }
 
+    /**
+     * Sets the field forceLoad.
+     * @param forceLoad the new value.
+     */
+    public void setForceLoad(boolean forceLoad) {
+        this.forceLoad = forceLoad;
+    }
+
     /**
      * Clears the cache.
      */

src/main/java/com/puppycrawl/tools/checkstyle/PackageObjectFactory.java

@@ -87,6 +87,9 @@ public class PackageObjectFactory implements ModuleFactory {
     /** Map of third party Checkstyle module names to the set of their fully qualified names. */
     private Map<String, Set<String>> thirdPartyNameToFullModuleNames;
 
+    /** If true old style force loading will be used. */
+    private boolean forceLoad;
+
     static {
         fillShortToFullModuleNamesMap();
     }
@@ -98,6 +101,18 @@ public class PackageObjectFactory implements ModuleFactory {
      *          core and custom modules
      */
     public PackageObjectFactory(Set<String> packageNames, ClassLoader moduleClassLoader) {
+        this(packageNames, moduleClassLoader, false);
+    }
+
+    /**
+     * Creates a new {@code PackageObjectFactory} instance.
+     * @param packageNames the list of package names to use
+     * @param moduleClassLoader class loader used to load Checkstyle
+     *          core and custom modules
+     * @param forceLoad force loading using
+     */
+    public PackageObjectFactory(Set<String> packageNames, ClassLoader moduleClassLoader,
+            boolean forceLoad) {
         if (moduleClassLoader == null) {
             throw new IllegalArgumentException(NULL_LOADER_MESSAGE);
         }
@@ -108,6 +123,7 @@ public PackageObjectFactory(Set<String> packageNames, ClassLoader moduleClassLoa
         //create a copy of the given set, but retain ordering
         packages = new LinkedHashSet<>(packageNames);
         this.moduleClassLoader = moduleClassLoader;
+        this.forceLoad = forceLoad;
     }
 
     /**
@@ -166,9 +182,8 @@ public Object createModule(String name) throws CheckstyleException {
                 instance = createObjectFromMap(name, thirdPartyNameToFullModuleNames);
             }
         }
-
         if (instance == null) {
-            instance = createObject(name);
+            instance = createFromFullName(name);
         }
         if (instance == null) {
             String attemptedNames = null;
@@ -307,6 +322,46 @@ private Object createObject(String className) throws CheckstyleException {
         return instance;
     }
 
+    /**
+     * Trying to create class with given full name (or name concatinated with &quot;Check&quot;)
+     * packages and then to force create (if enabled). Returns instance if class found or,
+     * otherwise, null.
+     * @param name the full name of a class.
+     * @return the {@code Object} created by loader.
+     * @throws CheckstyleException if an error occurs.
+     */
+    private Object createFromFullName(String name) throws CheckstyleException {
+        Object instance = createObject(name);
+        if (instance == null && forceLoad) {
+            instance = forceCreateModule(name);
+        }
+        return instance;
+    }
+
+    /**
+     * Searching to class with given name (or name concatinated with &quot;Check&quot;) in existing
+     * packages. Returns instance if class found or, otherwise, null.
+     * @param name the name of a class.
+     * @return the {@code Object} created by loader.
+     * @throws CheckstyleException if an error occurs.
+     */
+    private Object forceCreateModule(String name) throws CheckstyleException {
+        Object instance = null;
+        final Set<String> possibleNames = packages.stream()
+                .map(packageName -> packageName + PACKAGE_SEPARATOR + name)
+                .collect(Collectors.toSet());
+        possibleNames.addAll(possibleNames.stream()
+                .map(possibleName -> possibleName + CHECK_SUFFIX)
+                .collect(Collectors.toSet()));
+        for (String possibleName : possibleNames) {
+            instance = createObject(possibleName);
+            if (instance != null) {
+                break;
+            }
+        }
+        return instance;
+    }
+
     /**
      * Fill short-to-full module names map.
      */

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

@@ -275,6 +275,19 @@ public void testExistingTargetFile() throws Exception {
                 getPath("InputMain.java"));
     }
 
+    @Test
+    public void testExistingTargetFileWithForceLoad() throws Exception {
+
+        exit.checkAssertionAfterwards(() -> {
+            assertEquals("Unexpected ouput log", auditStartMessage.getMessage() + EOL
+                    + auditFinishMessage.getMessage() + EOL,
+                    systemOut.getLog());
+            assertEquals("Unexpected system error log", "", systemErr.getLog());
+        });
+        Main.main("-c", getPath("InputMainConfig-forceLoad-classname.xml"),
+                getPath("InputMain.java"));
+    }
+
     @Test
     public void testExistingTargetFileXmlOutput() throws Exception {
 

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

@@ -53,6 +53,7 @@
 import com.puppycrawl.tools.checkstyle.api.CheckstyleException;
 import com.puppycrawl.tools.checkstyle.api.FileText;
 import com.puppycrawl.tools.checkstyle.api.LocalizedMessage;
+import com.puppycrawl.tools.checkstyle.checks.annotation.AnnotationLocationCheck;
 import com.puppycrawl.tools.checkstyle.internal.utils.CheckUtil;
 
 /**
@@ -111,6 +112,18 @@ public void testCtorNullPackageException2() {
         }
     }
 
+    @Test
+    public void testCtorNullPackageException3() {
+        final ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+        try {
+            new PackageObjectFactory(Collections.singleton(null), classLoader, true);
+            fail("Exception is expected");
+        }
+        catch (IllegalArgumentException ex) {
+            assertEquals("Invalid exception message", NULL_PACKAGE_MESSAGE, ex.getMessage());
+        }
+    }
+
     @Test
     public void testMakeObjectFromName()
             throws CheckstyleException {
@@ -224,6 +237,57 @@ public void testCreateObjectFromFullModuleNamesWithCantInstantiateException() {
         }
     }
 
+    @Test
+    public void testCreateObjectFromFullModuleNamesWithCantInstantiateExceptionWithForceLoad() {
+        final String package1 = BASE_PACKAGE + ".wrong1";
+        final String package2 = BASE_PACKAGE + ".wrong2";
+        final ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+        final PackageObjectFactory objectFactory = new PackageObjectFactory(
+                new LinkedHashSet<>(Arrays.asList(package1, package2)), classLoader, true);
+        final String name = "FooCheck";
+        final String checkName = name + CHECK_SUFFIX;
+        try {
+            objectFactory.createModule(name);
+            fail("Exception is expected");
+        }
+        catch (CheckstyleException ex) {
+            final String attemptedNames = package1 + PACKAGE_SEPARATOR + name + STRING_SEPARATOR
+                    + package2 + PACKAGE_SEPARATOR + name + STRING_SEPARATOR
+                    + checkName + STRING_SEPARATOR
+                    + package1 + PACKAGE_SEPARATOR + checkName + STRING_SEPARATOR
+                    + package2 + PACKAGE_SEPARATOR + checkName;
+            final LocalizedMessage exceptionMessage = new LocalizedMessage(0,
+                    Definitions.CHECKSTYLE_BUNDLE, UNABLE_TO_INSTANTIATE_EXCEPTION_MESSAGE,
+                    new String[] {name, attemptedNames}, null, getClass(), null);
+            assertEquals("Invalid exception message",
+                    exceptionMessage.getMessage(), ex.getMessage());
+        }
+    }
+
+    @Test
+    public void testCreateObjectWithForceLoad() throws Exception {
+        final String className = "Checker";
+        final Method forceCreateModule = PackageObjectFactory.class.getDeclaredMethod(
+                "forceCreateModule", String.class);
+        forceCreateModule.setAccessible(true);
+        final Checker checker = (Checker) forceCreateModule.invoke(factory, className);
+        assertNotNull(checker);
+    }
+
+    @Test
+    public void testCreateCheckWithForceLoad() throws Exception {
+        final String checkName = "AnnotationLocation";
+        final Method createFromFullName = PackageObjectFactory.class.getDeclaredMethod(
+                "createFromFullName", String.class);
+        final PackageObjectFactory packageObjectFactory = new PackageObjectFactory(
+            new HashSet<>(Arrays.asList(BASE_PACKAGE, BASE_PACKAGE + ".checks.annotation")),
+            Thread.currentThread().getContextClassLoader(), true);
+        createFromFullName.setAccessible(true);
+        final AnnotationLocationCheck check = (AnnotationLocationCheck) createFromFullName.invoke(
+                packageObjectFactory, checkName);
+        assertNotNull(check);
+    }
+
     @Test
     @SuppressWarnings("unchecked")
     public void testGenerateThirdPartyNameToFullModuleNameWithException() throws Exception {

src/test/resources/com/puppycrawl/tools/checkstyle/main/InputMainConfig-forceLoad-classname.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<!DOCTYPE module PUBLIC
+        "-//Puppy Crawl//DTD Check Configuration 1.1//EN"
+        "http://checkstyle.sourceforge.net/dtds/configuration_1_1.dtd">
+
+<module name="Checker">
+    <property name="forceLoad" value="true"/>
+        <module name="TreeWalker">
+        <module name="TypeName">
+            <property name="severity" value="warning"/>
+        </module>
+    </module>
+</module>

src/xdocs/config.xml

@@ -356,6 +356,13 @@
             <td><code>true</code></td>
             <td>7.4</td>
           </tr>
+          <tr>
+            <td>forceLoad</td>
+            <td>If true old style force loading will be used</td>
+            <td><a href="property_types.html#boolean">Boolean</a></td>
+            <td><code>false</code></td>
+            <td>8.5</td>
+          </tr>
         </table>
       </subsection>