Issue checkstyle#78: extract: grab property info

config/findbugs-exclude.xml

@@ -27,4 +27,9 @@
         <Class name="~.*\.Immutable.*"/>
         <Bug pattern="NP_METHOD_PARAMETER_TIGHTENS_ANNOTATION"/>
     </Match>
+    <Match>
+        <!-- We can't change generated source code. -->
+        <Class name="~.*\.GsonAdapters.*"/>
+        <Bug pattern="URF_UNREAD_PUBLIC_OR_PROTECTED_FIELD"/>
+    </Match>
 </FindBugsFilter>

config/import-control.xml

@@ -51,4 +51,9 @@
         <allow pkg="org.eclipse.jgit"/>
         <allow pkg="org.apache.commons.lang"/>
     </subpackage>
+
+    <subpackage name="module">
+        <allow pkg="com.puppycrawl.tools.checkstyle"/>
+        <allow class="java.lang.reflect.Field"/>
+    </subpackage>
 </import-control>

config/pmd.xml

@@ -34,7 +34,11 @@
     <!-- we use class comments as source for xdoc files, so content is big and that is by design -->
     <exclude name="CommentSize"/>
   </rule>
-  <rule ref="rulesets/java/comments.xml/CommentRequired" />
+  <rule ref="rulesets/java/comments.xml/CommentRequired">
+    <properties>
+      <property name="publicMethodCommentRequirement" value="Ignored"/>
+    </properties>
+  </rule>
   <rule ref="rulesets/java/comments.xml/CommentSize">
     <properties>
       <!-- we use class comments as source for xdoc files, so content is big and that is by design -->

config/sevntu_suppressions.xml

@@ -4,5 +4,5 @@
         "http://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
 
 <suppressions>
-    <suppress checks="MultipleStringLiteralsExtended" files=".*[\\/]src[\\/]test[\\/]"/>
+    <suppress checks="MultipleStringLiteralsExtended" files="[\\/]ExtractInfoGeneratorTest.java$|.*[\\/]src[\\/]test[\\/]"/>
 </suppressions>

config/suppressions.xml

@@ -13,7 +13,7 @@
     <suppress checks="MagicNumber" files=".*[\\/]src[\\/]test[\\/]"/>
     <suppress checks="AvoidStaticImport" files=".*[\\/]src[\\/]test[\\/]"/>
     <suppress checks="WriteTag" files=".*[\\/]src[\\/]test[\\/]"/>
-    <suppress checks="MultipleStringLiterals" files=".*[\\/]src[\\/]test[\\/]"/>
+    <suppress checks="MultipleStringLiterals" files="[\\/]ExtractInfoGeneratorTest.java$|.*[\\/]src[\\/]test[\\/]"/>
 
     <suppress checks="AbstractClassName" files=".*[\\/]data[\\/]"/>
 </suppressions>

pom.xml

@@ -393,6 +393,11 @@
                                         <branchRate>0</branchRate>
                                         <lineRate>0</lineRate>
                                     </regex>
+                                    <regex>
+                                        <pattern>com.github.checkstyle.regression.module.UnitTestProcessorCheck</pattern>
+                                        <branchRate>76</branchRate>
+                                        <lineRate>92</lineRate>
+                                    </regex>
                                     <regex>
                                         <pattern>com.github.checkstyle.regression.report.ReportGenerator</pattern>
                                         <branchRate>0</branchRate>

src/main/java/com/github/checkstyle/regression/data/ModuleExtractInfo.java

@@ -19,6 +19,8 @@
 
 package com.github.checkstyle.regression.data;
 
+import java.util.List;
+
 import org.immutables.gson.Gson;
 import org.immutables.value.Value;
 
@@ -48,11 +50,46 @@ public abstract class ModuleExtractInfo {
      */
     public abstract String parent();
 
+    /**
+     * The properties of this module.
+     * @return the properties of this module
+     */
+    public abstract List<ModuleProperty> properties();
+
     /**
      * The full qualified name of this module.
      * @return the full qualified name of this module
      */
     public String fullName() {
         return packageName() + "." + name();
     }
+
+    /** Represents a property of checkstyle module. */
+    @Gson.TypeAdapters
+    @Value.Immutable
+    public interface ModuleProperty {
+        /**
+         * The name of this property.
+         * @return the name of this property
+         */
+        String name();
+
+        /**
+         * The type of this property.
+         * The value should be one of the followings:
+         *     - Pattern
+         *     - SeverityLevel
+         *     - boolean
+         *     - Scope
+         *     - double[]
+         *     - int[]
+         *     - String[]
+         *     - String
+         *     - URI
+         *     - AccessModifier[]
+         *     - int
+         * @return the type of this property
+         */
+        String type();
+    }
 }

src/main/java/com/github/checkstyle/regression/module/UnitTestProcessor.java

@@ -0,0 +1,115 @@
+////////////////////////////////////////////////////////////////////////////////
+// checkstyle: Checks Java source code for adherence to a set of rules.
+// Copyright (C) 2001-2017 the original author or authors.
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+////////////////////////////////////////////////////////////////////////////////
+
+package com.github.checkstyle.regression.module;
+
+import java.io.File;
+import java.lang.reflect.Field;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import com.github.checkstyle.regression.data.ModuleInfo;
+import com.puppycrawl.tools.checkstyle.Checker;
+import com.puppycrawl.tools.checkstyle.DefaultConfiguration;
+import com.puppycrawl.tools.checkstyle.TreeWalker;
+import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
+import com.puppycrawl.tools.checkstyle.api.CheckstyleException;
+import com.puppycrawl.tools.checkstyle.api.Configuration;
+import com.puppycrawl.tools.checkstyle.api.FileSetCheck;
+
+/**
+ * Processes the unit test class of a checkstyle module.
+ * This utility class would run {@link UnitTestProcessorCheck} on the file with
+ * the given path and return the collected property info.
+ * @author LuoLiangchen
+ */
+public final class UnitTestProcessor {
+    /** Prevents instantiation. */
+    private UnitTestProcessor() {
+    }
+
+    /**
+     * Processes the unit test class with the given path.
+     * @param path the path of the unit test class
+     * @return the unit test method name to properties map
+     * @throws CheckstyleException          failure when running the check
+     * @throws ReflectiveOperationException failure of reflection on checker and tree walker
+     */
+    public static Map<String, Set<ModuleInfo.Property>> process(String path)
+            throws CheckstyleException, ReflectiveOperationException {
+        final DefaultConfiguration moduleConfig = createModuleConfig(UnitTestProcessorCheck.class);
+        final Configuration dc = createTreeWalkerConfig(moduleConfig);
+        final Checker checker = new Checker();
+        checker.setModuleClassLoader(Thread.currentThread().getContextClassLoader());
+        checker.configure(dc);
+        final List<File> processedFiles = Collections.singletonList(new File(path));
+        checker.process(processedFiles);
+
+        final UnitTestProcessorCheck check = getCheckInstance(checker);
+        return check.getUnitTestToPropertiesMap();
+    }
+
+    /**
+     * Gets the instance of {@link UnitTestProcessorCheck} from the checker.
+     * @param checker the checker which run the check
+     * @return the instance of {@link UnitTestProcessorCheck}
+     * @throws ReflectiveOperationException failure of reflection
+     */
+    @SuppressWarnings("unchecked")
+    private static UnitTestProcessorCheck getCheckInstance(Checker checker)
+            throws ReflectiveOperationException {
+        final Field fileSetChecks = checker.getClass().getDeclaredField("fileSetChecks");
+        fileSetChecks.setAccessible(true);
+        final TreeWalker treeWalker =
+                (TreeWalker) ((List<FileSetCheck>) fileSetChecks.get(checker)).get(0);
+        final Field ordinaryChecks = treeWalker.getClass().getDeclaredField("ordinaryChecks");
+        ordinaryChecks.setAccessible(true);
+        final Set<AbstractCheck> checks = (Set<AbstractCheck>) ordinaryChecks.get(treeWalker);
+        return (UnitTestProcessorCheck) checks.iterator().next();
+    }
+
+    /**
+     * Creates {@link DefaultConfiguration} for the {@link TreeWalker}
+     * based on the given {@link Configuration} instance.
+     * @param config {@link Configuration} instance.
+     * @return {@link DefaultConfiguration} for the {@link TreeWalker}
+     *      based on the given {@link Configuration} instance.
+     */
+    private static DefaultConfiguration createTreeWalkerConfig(Configuration config) {
+        final DefaultConfiguration dc =
+                new DefaultConfiguration("configuration");
+        final DefaultConfiguration twConf = createModuleConfig(TreeWalker.class);
+        // make sure that the tests always run with this charset
+        dc.addAttribute("charset", "UTF-8");
+        dc.addChild(twConf);
+        twConf.addChild(config);
+        return dc;
+    }
+
+    /**
+     * Creates {@link DefaultConfiguration} for the given class.
+     * @param clazz the class of module
+     * @return the {@link DefaultConfiguration} of the module class
+     */
+    private static DefaultConfiguration createModuleConfig(Class<?> clazz) {
+        return new DefaultConfiguration(clazz.getName());
+    }
+}