Fix regression separating classpath entries - #2961 (#2977)

* Fix regression separating classpath entries - #2961

* Use File.pathSeparaterChar to join classpath

* Swap separator chars in comment

detekt-core/src/main/kotlin/io/gitlab/arturbosch/detekt/core/settings/EnvironmentAware.kt

@@ -43,7 +43,7 @@ internal class EnvironmentFacade(
 }
 
 internal fun CompilerSpec.classpathEntries(): List<String> =
-    classpath?.split(":;") ?: emptyList() // support both windows : and unix ;
+    classpath?.split(":", ";") ?: emptyList() // support both windows ; and unix :
 
 internal fun CompilerSpec.parseLanguageVersion(): LanguageVersion? {
     fun parse(value: String): LanguageVersion {

detekt-core/src/test/kotlin/io/gitlab/arturbosch/detekt/core/settings/EnvironmentFacadeSpec.kt

@@ -0,0 +1,33 @@
+package io.gitlab.arturbosch.detekt.core.settings
+
+import io.gitlab.arturbosch.detekt.core.createNullLoggingSpec
+import io.gitlab.arturbosch.detekt.core.createProcessingSettings
+import org.assertj.core.api.Assertions.assertThat
+import org.spekframework.spek2.Spek
+import org.spekframework.spek2.style.specification.describe
+
+internal class EnvironmentFacadeSpec : Spek({
+
+    describe("classpath entries can be separated by : or ;") {
+
+        arrayOf(
+            "supports ;" to "file1;file2;file3",
+            "supports :" to "file1:file2:file3",
+            "supports mixing ; and :" to "file1;file2:file3"
+        ).forEach { (testName, classpath) ->
+            it(testName) {
+                testSettings(classpath).use {
+                    assertThat(it.classpath).hasSize(3)
+                }
+            }
+        }
+    }
+})
+
+private fun testSettings(classpath: String) = createProcessingSettings(
+    spec = createNullLoggingSpec {
+        compiler {
+            this.classpath = classpath
+        }
+    }
+)

detekt-gradle-plugin/src/main/kotlin/io/gitlab/arturbosch/detekt/invoke/CliArgument.kt

@@ -3,6 +3,7 @@ package io.gitlab.arturbosch.detekt.invoke
 import io.gitlab.arturbosch.detekt.extensions.DetektReportType
 import org.gradle.api.file.FileCollection
 import org.gradle.api.file.RegularFile
+import java.io.File
 
 private const val DEBUG_PARAMETER = "--debug"
 private const val INPUT_PARAMETER = "--input"
@@ -39,7 +40,7 @@ internal data class InputArgument(val fileCollection: FileCollection) : CliArgum
 internal data class ClasspathArgument(val fileCollection: FileCollection) : CliArgument() {
     override fun toArgument() = if (!fileCollection.isEmpty) listOf(
         CLASSPATH_PARAMETER,
-        fileCollection.joinToString(";") { it.absolutePath }) else emptyList()
+        fileCollection.joinToString(File.pathSeparator) { it.absolutePath }) else emptyList()
 }
 
 internal data class LanguageVersionArgument(val languageVersion: String?) : CliArgument() {