Issue checkstyle#77: git: add line changes detection

config/import-control.xml

@@ -49,5 +49,6 @@
 
     <subpackage name="git">
         <allow pkg="org.eclipse.jgit"/>
+        <allow pkg="org.apache.commons.lang"/>
     </subpackage>
 </import-control>

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

@@ -19,6 +19,8 @@
 
 package com.github.checkstyle.regression.data;
 
+import java.util.List;
+
 import org.immutables.value.Value;
 
 /**
@@ -32,4 +34,18 @@ public interface GitChange {
      * @return the path of the changed file
      */
     String path();
+
+    /**
+     * The line numbers of the added changes.
+     * The first line of a file is marked as line zero.
+     * @return the line numbers of the added changes
+     */
+    List<Integer> addedLines();
+
+    /**
+     * The line numbers of the deleted changes.
+     * The first line of a file is marked as line zero.
+     * @return the line numbers of the deleted changes
+     */
+    List<Integer> deletedLines();
 }

src/main/java/com/github/checkstyle/regression/git/DiffParser.java

@@ -21,12 +21,16 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.util.Arrays;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.stream.Collectors;
 
+import org.apache.commons.lang.math.IntRange;
 import org.eclipse.jgit.api.Git;
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.diff.DiffEntry;
+import org.eclipse.jgit.diff.DiffFormatter;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevCommit;
@@ -36,6 +40,7 @@
 import org.eclipse.jgit.storage.file.FileRepositoryBuilder;
 import org.eclipse.jgit.treewalk.AbstractTreeIterator;
 import org.eclipse.jgit.treewalk.CanonicalTreeParser;
+import org.eclipse.jgit.util.io.DisabledOutputStream;
 
 import com.github.checkstyle.regression.data.GitChange;
 import com.github.checkstyle.regression.data.ImmutableGitChange;
@@ -44,6 +49,7 @@
  * Parses git diff between PR branch and master for the further use.
  * @author LuoLiangchen
  */
+// -@cs[ClassDataAbstractionCoupling] We have to import many classes from JGit
 public final class DiffParser {
     /** Prevents instantiation. */
     private DiffParser() {
@@ -59,24 +65,28 @@ private DiffParser() {
      */
     public static List<GitChange> parse(String repositoryPath, String branchName)
             throws IOException, GitAPIException {
-        final List<GitChange> returnValue;
+        final List<GitChange> returnValue = new LinkedList<>();
         final File gitDir = new File(repositoryPath, ".git");
         final Repository repository = new FileRepositoryBuilder().setGitDir(gitDir)
                 .readEnvironment().findGitDir().build();
 
         try {
             final TreeParserPair pair = getTreeParserPair(repository, branchName);
             final Git git = new Git(repository);
+            final DiffFormatter formatter = new DiffFormatter(DisabledOutputStream.INSTANCE);
+            formatter.setRepository(repository);
 
             try {
-                returnValue = git.diff()
+                final List<DiffEntry> diffs = git.diff()
                         .setOldTree(pair.commonAncestorTreeParser)
                         .setNewTree(pair.prTreeParser)
                         .call()
                         .stream()
                         .filter(entry -> entry.getChangeType() != DiffEntry.ChangeType.DELETE)
-                        .map(DiffParser::convertDiffEntryToGitChange)
                         .collect(Collectors.toList());
+                for (DiffEntry diff : diffs) {
+                    returnValue.add(convertDiffEntryToGitChange(diff, formatter));
+                }
             }
             finally {
                 git.close();
@@ -158,11 +168,28 @@ private static AbstractTreeIterator prepareTreeParser(RevWalk walk, RevCommit co
     /**
      * Converts a {@link DiffEntry} to {@link GitChange} for the further use.
      * @param diffEntry the {@link DiffEntry} instance to be converted
+     * @param formatter the diff formatter to provide the line changes information
      * @return the {@link GitChange} instance converted from the given {@link DiffEntry}
+     * @throws IOException JGit library exception
      */
-    private static GitChange convertDiffEntryToGitChange(DiffEntry diffEntry) {
+    private static GitChange convertDiffEntryToGitChange(
+            DiffEntry diffEntry, DiffFormatter formatter) throws IOException {
+        final List<Integer> addedLines = formatter.toFileHeader(diffEntry).toEditList().stream()
+                .filter(edit -> edit.getBeginB() < edit.getEndB())
+                .flatMapToInt(edit -> Arrays.stream(
+                        new IntRange(edit.getBeginB(), edit.getEndB() - 1).toArray()))
+                .boxed()
+                .collect(Collectors.toList());
+        final List<Integer> deletedLines = formatter.toFileHeader(diffEntry).toEditList().stream()
+                .filter(edit -> edit.getBeginA() < edit.getEndA())
+                .flatMapToInt(edit -> Arrays.stream(
+                        new IntRange(edit.getBeginA(), edit.getEndA() - 1).toArray()))
+                .boxed()
+                .collect(Collectors.toList());
         return ImmutableGitChange.builder()
                 .path(diffEntry.getNewPath())
+                .addAllAddedLines(addedLines)
+                .addAllDeletedLines(deletedLines)
                 .build();
     }
 

src/test/java/com/github/checkstyle/regression/git/DiffParserTest.java

@@ -79,6 +79,7 @@ public void testParseModifyChange() throws Exception {
             assertEquals("There should be 1 change detected", 1, changes.size());
             final GitChange expected = ImmutableGitChange.builder()
                     .path("HelloWorld")
+                    .addAddedLines(0)
                     .build();
             assertEquals("The change is not as expected", expected, changes.get(0));
         }
@@ -203,4 +204,71 @@ public void testParseFilePermissionChange() throws Exception {
             }
         }
     }
+
+    @Test
+    public void testParseLineChangesAddLine() throws Exception {
+        try (Repository repository = GitUtils.createNewRepository()) {
+            final File helloWorld = GitUtils.addAnEmptyFileAndCommit(repository, "HelloWorld");
+            Files.write(helloWorld.toPath(), "line 0\n"
+                    .getBytes(Charset.forName("UTF-8")), StandardOpenOption.APPEND);
+            GitUtils.addAllAndCommit(repository, "add original line");
+            GitUtils.createNewBranchAndCheckout(repository, "foo");
+            Files.write(helloWorld.toPath(), "line 1 added\nline 2 added\n"
+                    .getBytes(Charset.forName("UTF-8")), StandardOpenOption.APPEND);
+            GitUtils.addAllAndCommit(repository, "add line 1, 2");
+            final List<GitChange> changes = DiffParser.parse(
+                    repository.getDirectory().getParent(), "foo");
+            assertEquals("There should be 1 change detected", 1, changes.size());
+            final GitChange expected = ImmutableGitChange.builder()
+                    .path("HelloWorld")
+                    .addAddedLines(1, 2)
+                    .build();
+            assertEquals("The change is not as expected", expected, changes.get(0));
+        }
+    }
+
+    @Test
+    public void testParseLineChangesRemoveLine() throws Exception {
+        try (Repository repository = GitUtils.createNewRepository()) {
+            final File helloWorld = GitUtils.addAnEmptyFileAndCommit(repository, "HelloWorld");
+            Files.write(helloWorld.toPath(), "line 0\nline 1 to be removed\nline 2 to be removed\n"
+                    .getBytes(Charset.forName("UTF-8")), StandardOpenOption.APPEND);
+            GitUtils.addAllAndCommit(repository, "add original three lines");
+            GitUtils.createNewBranchAndCheckout(repository, "foo");
+            Files.write(helloWorld.toPath(), "line 0\n"
+                    .getBytes(Charset.forName("UTF-8")), StandardOpenOption.TRUNCATE_EXISTING);
+            GitUtils.addAllAndCommit(repository, "remove two lines");
+            final List<GitChange> changes = DiffParser.parse(
+                    repository.getDirectory().getParent(), "foo");
+            assertEquals("There should be 1 change detected", 1, changes.size());
+            final GitChange expected = ImmutableGitChange.builder()
+                    .path("HelloWorld")
+                    .addDeletedLines(1, 2)
+                    .build();
+            assertEquals("The change is not as expected", expected, changes.get(0));
+        }
+    }
+
+    @Test
+    public void testParseLineChangesModifyLine() throws Exception {
+        try (Repository repository = GitUtils.createNewRepository()) {
+            final File helloWorld = GitUtils.addAnEmptyFileAndCommit(repository, "HelloWorld");
+            Files.write(helloWorld.toPath(), "line 0\nline 1\nline 2\n"
+                    .getBytes(Charset.forName("UTF-8")), StandardOpenOption.APPEND);
+            GitUtils.addAllAndCommit(repository, "add original three lines");
+            GitUtils.createNewBranchAndCheckout(repository, "foo");
+            Files.write(helloWorld.toPath(), "line 0\nline 1 changed\nline 2 changed\n"
+                    .getBytes(Charset.forName("UTF-8")), StandardOpenOption.TRUNCATE_EXISTING);
+            GitUtils.addAllAndCommit(repository, "modify two lines");
+            final List<GitChange> changes = DiffParser.parse(
+                    repository.getDirectory().getParent(), "foo");
+            assertEquals("There should be 1 change detected", 1, changes.size());
+            final GitChange expected = ImmutableGitChange.builder()
+                    .path("HelloWorld")
+                    .addAddedLines(1, 2)
+                    .addDeletedLines(1, 2)
+                    .build();
+            assertEquals("The change is not as expected", expected, changes.get(0));
+        }
+    }
 }