support running rules from source on WIndows

docs/developers/tutorial.md

@@ -629,6 +629,8 @@ custom rule using the `file:/path/to/NamedLiteralArguments.scala` syntax.
 scalafix --rules=file:/path/to/NamedLiteralArguments.scala
 ```
 
+On Windows, the URI syntax is `file:///C:/Users/...`.
+
 ### Using `http:`
 
 Another way to run a rule from source is to publish it as a gist and share the

scalafix-reflect/src/main/scala/scalafix/internal/reflect/RuleDecoderOps.scala

@@ -7,6 +7,7 @@ import java.nio.file.Path
 import java.nio.file.Paths
 
 import scala.collection.concurrent.TrieMap
+import scala.util.Try
 
 import scala.meta.io.AbsolutePath
 
@@ -100,7 +101,9 @@ object RuleDecoderOps {
       )
     def unapply(arg: Conf.Str): Option[Configured[Input]] = arg match {
       case UriRule("file", uri) =>
-        val path = AbsolutePath(Paths.get(uri.getSchemeSpecificPart))(cwd)
+        val path = AbsolutePath(
+          Try(Paths.get(uri)).getOrElse(Paths.get(uri.getSchemeSpecificPart))
+        )(cwd)
         Option(Ok(Input.File(path.toNIO)))
       case UrlRule(Ok(url)) =>
         try {

scalafix-reflect/src/main/scala/scalafix/internal/reflect/ScalafixToolbox.scala

@@ -2,6 +2,7 @@ package scalafix.internal.reflect
 
 import java.io.File
 import java.net.URLClassLoader
+import java.nio.file.Paths
 import java.util.function
 
 import metaconfig.Configured
@@ -49,7 +50,9 @@ class ScalafixToolbox {
   ): Configured[CompiledRules] =
     synchronized {
       val classpath =
-        toolClasspath.getURLs.map(_.getPath).mkString(File.pathSeparator)
+        toolClasspath.getURLs
+          .map(url => Paths.get(url.toURI))
+          .mkString(File.pathSeparator)
       val compiler = compilerCache.computeIfAbsent(classpath, newCompiler)
       (
         compiler.compile(code) |@|

scalafix-tests/integration/src/test/scala/scalafix/tests/interfaces/ScalafixSuite.scala

@@ -11,7 +11,6 @@ import org.scalatest.funsuite.AnyFunSuite
 import scalafix.interfaces.Scalafix
 import scalafix.interfaces.ScalafixDiagnostic
 import scalafix.interfaces.ScalafixMainCallback
-import scalafix.internal.tests.utils.SkipWindows
 
 /**
  * Tests in this suite require scalafix-cli & its dependencies to be
@@ -28,10 +27,7 @@ class ScalafixSuite extends AnyFunSuite {
   }
 
   def fetchAndLoad(scalaVersion: String): Unit = {
-    test(
-      s"fetch & load instance for Scala version $scalaVersion",
-      SkipWindows
-    ) {
+    test(s"fetch & load instance for Scala version $scalaVersion") {
       val scalafixAPI = Scalafix.fetchAndClassloadInstance(
         scalaVersion,
         Seq[Repository](
@@ -66,11 +62,11 @@ class ScalafixSuite extends AnyFunSuite {
           maybeDiagnostic = Some(diagnostic)
       }
       args
-        .withPaths(
-          Seq(ruleSource).asJava
-        ) // any file would do, we just want rules to be loaded
-        .withRules(Seq(s"file:$ruleSource").asJava)
+        .withRules(Seq(ruleSource.toUri.toString).asJava)
         .withMainCallback(scalafixMainCallback)
+        // any target file would do to emit a diagnostic, so run the rule on itself
+        .withPaths(List(ruleSource).asJava)
+        .withWorkingDirectory(ruleSource.getParent)
         .run()
       assert(maybeDiagnostic.get.message.startsWith(scalaVersion))
     }

scalafix-tests/integration/src/test/scala/scalafix/tests/reflect/RuleDecoderSuite.scala

@@ -29,17 +29,26 @@ class RuleDecoderSuite extends AnyFunSuite {
   val decoder: ConfDecoder[Rules] = RuleDecoder.decoder(decoderSettings)
   val expectedName = "NoDummy"
 
-  test("absolute path resolves as is", SkipWindows) {
+  test("absolute path resolves as URI") {
+    val rules = decoder.read(Conf.Str(abspath.toURI.toString)).get
+    assert(expectedName == rules.name.value)
+  }
+
+  test(
+    "absolute path resolves as is",
+    // heading slashes are needed on Windows, see https://en.wikipedia.org/wiki/File_URI_scheme#Examples
+    SkipWindows
+  ) {
     val rules = decoder.read(Conf.Str(s"file:$abspath")).get
     assert(expectedName == rules.name.value)
   }
 
-  test("relative resolves from custom working directory", SkipWindows) {
+  test("relative resolves from custom working directory") {
     val rules = decoder.read(Conf.Str(s"file:$relpath")).get
     assert(expectedName == rules.name.value)
   }
 
-  test("resolved classes can be reloaded", SkipWindows) {
+  test("resolved classes can be reloaded") {
     val tmp = Files.createTempFile("scalafix", "CustomRule.scala")
 
     val customRuleV1 =
@@ -49,7 +58,7 @@ class RuleDecoderSuite extends AnyFunSuite {
       """.stripMargin
     Files.write(tmp, customRuleV1.getBytes)
     val rules1 =
-      decoder.read(Conf.Str(s"file:${tmp.toFile.getAbsolutePath}")).get
+      decoder.read(Conf.Str(tmp.toUri.toString)).get
     val class1 = rules1.rules.head.getClass
 
     val customRuleV2 =
@@ -61,7 +70,7 @@ class RuleDecoderSuite extends AnyFunSuite {
       """.stripMargin
     Files.write(tmp, customRuleV2.getBytes)
     val rules2 =
-      decoder.read(Conf.Str(s"file:${tmp.toFile.getAbsolutePath}")).get
+      decoder.read(Conf.Str(tmp.toUri.toString)).get
     val class2 = rules2.rules.head.getClass
 
     assert(!class1.isAssignableFrom(class2))