Allow sbt-scoverage to work on Windows

The -Xplugin option expects a classpath string with multiple paths
separated by a semicolon or colon depending on the operating system.
However, this currently always uses a colon, which doesn't work on
Windows. This means scalac cannot find the scoverage plugin jars and
leads to errors about "bad options".

This modifies the -Xplugin logic to use File.pathSeparator when building
the Xplugin classpath, allowing it to work regardless of operating
system.

Also modifies excludedPackages when on Windows to replace Unix path
separators with Windows path separators (which are escaped because it is
treated as a regular expression). Modifies tests to remove unnecessary
escaping of Unix separators that results in an invalid regex due to this
replacement on Windows.

Note that two tests currently prevent CI from working on Windows:
coverage-off and preserve-set. The reason for these failures on Windows
is not clear, but these changes at least allow the common uses to work
on Windows.

.github/workflows/ci.yml

@@ -11,10 +11,11 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
         java: [ '8', '17' ]
+        os: [ 'ubuntu-latest' ]
 
     steps:
       - name: checkout the repo

src/main/scala/scoverage/ScoverageSbtPlugin.scala

@@ -2,6 +2,7 @@ package scoverage
 
 import sbt.Keys._
 import sbt._
+import sbt.internal.util.Util.isWindows
 import sbt.plugins.JvmPlugin
 import scoverage.reporter.CoberturaXmlWriter
 import scoverage.domain.Constants
@@ -147,7 +148,7 @@ object ScoverageSbtPlugin extends AutoPlugin {
 
         Seq(
           Some(
-            s"-Xplugin:${pluginPaths.mkString(":")}"
+            s"-Xplugin:${pluginPaths.mkString(java.io.File.pathSeparator)}"
           ),
           Some(
             s"-P:scoverage:dataDir:${coverageDataDir.value.getAbsolutePath}/scoverage-data"
@@ -160,6 +161,13 @@ object ScoverageSbtPlugin extends AutoPlugin {
             .map(v => s"-P:scoverage:excludedPackages:$v"),
           Option(coverageExcludedFiles.value.trim)
             .filter(_.nonEmpty)
+            .map(v =>
+              // On windows, replace unix file separators with windows file
+              // separators. Note that we need to replace / with \\ because
+              // the plugin treats this string as a regular expression and
+              // backslashes must be escaped in regular expressions.
+              if (isWindows) v.replace("/", """\\""") else v
+            )
             .map(v => s"-P:scoverage:excludedFiles:$v"),
           Some("-P:scoverage:reportTestName"),
           // rangepos is broken in some releases of scala so option to turn it off

src/sbt-test/scoverage/coverage-excluded-files/build.sbt

@@ -4,7 +4,7 @@ scalaVersion := "2.13.6"
 
 libraryDependencies += "org.scalameta" %% "munit" % "0.7.29" % Test
 
-coverageExcludedFiles := ".*\\/two\\/GoodCoverage"
+coverageExcludedFiles := ".*/two/GoodCoverage"
 
 resolvers ++= {
   if (sys.props.get("plugin.version").exists(_.endsWith("-SNAPSHOT")))

src/sbt-test/scoverage/scala3-coverage-excluded-files/build.sbt

@@ -4,7 +4,7 @@ scalaVersion := "3.2.0-RC1"
 
 libraryDependencies += "org.scalameta" %% "munit" % "0.7.29" % Test
 
-coverageExcludedFiles := ".*\\/two\\/GoodCoverage"
+coverageExcludedFiles := ".*/two/GoodCoverage"
 
 resolvers ++= {
   if (sys.props.get("plugin.version").exists(_.endsWith("-SNAPSHOT")))