Merge branch 'pr-2171'

[core] Preserve newlines in DocumentFile

docs/pages/release_notes.md

@@ -44,6 +44,7 @@ the implementation based on your feedback.
 
 *   core
     *   [#2006](https://github.com/pmd/pmd/issues/2006): \[core] PMD should warn about multiple instances of the same rule in a ruleset
+    *   [#2170](https://github.com/pmd/pmd/issues/2170): \[core] DocumentFile doesn't preserve newlines
 *   java-bestpractices
     *   [#2149](https://github.com/pmd/pmd/issues/2149): \[java] JUnitAssertionsShouldIncludeMessage - False positive with assertEquals and JUnit5
 *   java-codestyle

pmd-core/src/main/java/net/sourceforge/pmd/document/DocumentFile.java

@@ -21,6 +21,8 @@ import java.util.Scanner;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+import org.apache.commons.io.IOUtils;
+
 /**
  * Implementation that handles a Document as a file in the filesystem and receives operations in a sorted manner
  * (i.e. the regions are sorted). This improves the efficiency of reading the file by only scanning it once while
@@ -157,11 +159,7 @@ public class DocumentFile implements Document, Closeable {
     }
 
     private void writeUntilEOF() throws IOException {
-        String line;
-
-        while ((line = reader.readLine()) != null) {
-            writer.write(line);
-        }
+        IOUtils.copy(reader, writer);
     }
 
     /* package-private */ List<Integer> getLineToOffset() {

pmd-core/src/test/java/net/sourceforge/pmd/document/DocumentFileTest.java

@@ -16,6 +16,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
+import org.apache.commons.io.IOUtils;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
@@ -48,6 +49,22 @@ public class DocumentFileTest {
         }
     }
 
+    @Test
+    public void shouldPreserveNewlines() throws IOException {
+        final String testFileContent = IOUtils.toString(
+                DocumentFileTest.class.getResource("ShouldPreserveNewlines.java"), StandardCharsets.UTF_8);
+        writeContentToTemporaryFile(testFileContent);
+
+        try (DocumentFile documentFile = new DocumentFile(temporaryFile, StandardCharsets.UTF_8)) {
+            documentFile.insert(0, 0, "public ");
+        }
+
+        try (FileInputStream stream = new FileInputStream(temporaryFile)) {
+            final String actualContent = new String(readAllBytes(stream));
+            assertEquals("public " + testFileContent, actualContent);
+        }
+    }
+
     private byte[] readAllBytes(final FileInputStream stream) throws IOException {
         final int defaultBufferSize = 8192;
         final int maxBufferSize = Integer.MAX_VALUE - 8;

pmd-core/src/test/resources/net/sourceforge/pmd/document/ShouldPreserveNewlines.java

@@ -0,0 +1,8 @@
+class ShouldPreserveNewlines {
+    public static void main(String[] args) {
+        System.out.println("Test");
+    }
+}
+// note: multiple empty lines at the end
+
+