https://github.com/scoverage/scalac-scoverage-plugin/pull/109 introduced...

scalac-scoverage-plugin/src/main/scala/scoverage/IOUtils.scala

@@ -82,23 +82,4 @@ object IOUtils {
     acc
   }
 
-  /**
-   * Converts absolute path to relative one if any of the source directories is it's parent.
-   * If there is no parent directory, the path is returned unchanged (absolute).
-   * 
-   * @param src absolute file path in canonical form
-   * @param sourcePaths absolute source paths in canonical form WITH trailing file separators
-   */
-  def relativeSource(src: String, sourcePaths: Seq[String]): String = {
-    val sourceRoot: Option[String] = sourcePaths.find(
-      sourcePath => src.startsWith(sourcePath)
-    )
-    sourceRoot match {
-      case Some(path: String) => src.replace(path, "")
-      case _ =>
-        val fmtSourcePaths: String = sourcePaths.mkString("'", "', '", "'")
-        throw new RuntimeException(s"No source root found for '$src' (source roots: $fmtSourcePaths)");
-    }
-  }
-
 }

scalac-scoverage-plugin/src/main/scala/scoverage/report/BaseReportWriter.scala

@@ -0,0 +1,30 @@
+package scoverage.report
+
+import java.io.File
+
+class BaseReportWriter(sourceDirectories: Seq[File], outputDir: File) {
+
+  // Source paths in canonical form WITH trailing file separator
+  private val formattedSourcePaths: Seq[String] = sourceDirectories filter ( _.isDirectory ) map ( _.getCanonicalPath + File.separator )
+
+  /**
+   * Converts absolute path to relative one if any of the source directories is it's parent.
+   * If there is no parent directory, the path is returned unchanged (absolute).
+   * 
+   * @param src absolute file path in canonical form
+   */
+  def relativeSource(src: String): String = relativeSource(src, formattedSourcePaths)
+
+  private def relativeSource(src: String, sourcePaths: Seq[String]): String = {
+    val sourceRoot: Option[String] = sourcePaths.find(
+      sourcePath => src.startsWith(sourcePath)
+    )
+    sourceRoot match {
+      case Some(path: String) => src.replace(path, "")
+      case _ =>
+        val fmtSourcePaths: String = sourcePaths.mkString("'", "', '", "'")
+        throw new RuntimeException(s"No source root found for '$src' (source roots: $fmtSourcePaths)");
+    }
+  }
+
+}

scalac-scoverage-plugin/src/main/scala/scoverage/report/CoberturaXmlWriter.scala

@@ -7,14 +7,11 @@ import scoverage._
 import scala.xml.{Node, PrettyPrinter}
 
 /** @author Stephen Samuel */
-class CoberturaXmlWriter(sourceDirectories: Seq[File], outputDir: File) {
+class CoberturaXmlWriter(sourceDirectories: Seq[File], outputDir: File) extends BaseReportWriter(sourceDirectories, outputDir) {
 
   def this (baseDir: File, outputDir: File) {
     this(Seq(baseDir), outputDir);
   }
-
-  // Source paths in canonical form WITH trailing file separator
-  val formattedSourcePaths: Seq[String] = sourceDirectories filter ( _.isDirectory ) map ( _.getCanonicalPath + File.separator )
 
   def format(double: Double): String = "%.2f".format(double)
 
@@ -95,6 +92,4 @@ class CoberturaXmlWriter(sourceDirectories: Seq[File], outputDir: File) {
     </coverage>
   }
 
-  private def relativeSource(src: String): String = IOUtils.relativeSource(src, formattedSourcePaths)
-
 }

scalac-scoverage-plugin/src/main/scala/scoverage/report/ScoverageHtmlWriter.scala

@@ -8,14 +8,11 @@ import scoverage._
 import scala.xml.Node
 
 /** @author Stephen Samuel */
-class ScoverageHtmlWriter(sourceDirectories: Seq[File], outputDir: File) {
+class ScoverageHtmlWriter(sourceDirectories: Seq[File], outputDir: File) extends BaseReportWriter(sourceDirectories, outputDir) {
 
   def this (sourceDirectory: File, outputDir: File) {
     this(Seq(sourceDirectory), outputDir);
   }
-
-  // Source paths in canonical form WITH trailing file separator
-  val formattedSourcePaths: Seq[String] = sourceDirectories filter ( _.isDirectory ) map ( _.getCanonicalPath + File.separator )
 
   def write(coverage: Coverage): Unit = {
     val indexFile = new File(outputDir.getAbsolutePath + "/index.html")
@@ -537,7 +534,4 @@ class ScoverageHtmlWriter(sourceDirectories: Seq[File], outputDir: File) {
       </script>
   }
 
-  private def relativeSource(src: String): String = IOUtils.relativeSource(src, formattedSourcePaths)
-
 }
-

scalac-scoverage-plugin/src/main/scala/scoverage/report/ScoverageXmlWriter.scala

@@ -2,20 +2,17 @@ package scoverage.report
 
 import java.io.File
 
-import _root_.scoverage._
+import scoverage._
 
 import scala.xml.{Node, PrettyPrinter}
 
 /** @author Stephen Samuel */
-class ScoverageXmlWriter(sourceDirectories: Seq[File], outputDir: File, debug: Boolean) {
+class ScoverageXmlWriter(sourceDirectories: Seq[File], outputDir: File, debug: Boolean) extends BaseReportWriter(sourceDirectories, outputDir) {
 
   def this (sourceDir: File, outputDir: File, debug: Boolean) {
     this(Seq(sourceDir), outputDir, debug);
   }
 
-  // Source paths in canonical form WITH trailing file separator
-  val formattedSourcePaths: Seq[String] = sourceDirectories filter ( _.isDirectory ) map ( _.getCanonicalPath + File.separator )
-
   def write(coverage: Coverage): Unit = {
     val file = IOUtils.reportFile(outputDir, debug)
     IOUtils.writeToFile(file, new PrettyPrinter(120, 4).format(xml(coverage)))
@@ -103,7 +100,4 @@ class ScoverageXmlWriter(sourceDirectories: Seq[File], outputDir: File, debug: B
     </package>
   }
 
-  private def relativeSource(src: String): String = IOUtils.relativeSource(src, formattedSourcePaths)
-
 }
-