Fixes to AbstractQuickFixTest (full path to file and file separator)

The full path to file in getTestDataPath is necessary to show file diff link in exception when the test fails.
The File.separatorChar fixes tests on Windows machines.

idea/tests/org/jetbrains/kotlin/idea/quickfix/AbstractQuickFixTest.kt

@@ -38,6 +38,7 @@ import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.test.InTextDirectivesUtils
 import org.junit.Assert
 import java.io.File
+import java.io.IOException
 
 abstract class AbstractQuickFixTest : KotlinLightCodeInsightFixtureTestCase() {
     @Throws(Exception::class)
@@ -115,7 +116,7 @@ abstract class AbstractQuickFixTest : KotlinLightCodeInsightFixtureTestCase() {
     }
 
     private fun applyAction(contents: String, testFullPath: String) {
-        val fileName = testFullPath.substringAfterLast("/", "")
+        val fileName = testFullPath.substringAfterLast(File.separatorChar, "")
         val actionHint = ActionHint.parse(myFixture.file, contents.replace("\${file}", fileName, ignoreCase = true))
         val intention = findActionWithText(actionHint.expectedText)
         if (actionHint.shouldPresent()) {
@@ -227,4 +228,17 @@ abstract class AbstractQuickFixTest : KotlinLightCodeInsightFixtureTestCase() {
     fun checkForUnexpectedErrors() {
         DirectiveBasedActionUtils.checkForUnexpectedErrors(myFixture.file as KtFile)
     }
+
+    override fun getTestDataPath(): String {
+        // Ensure full path is returned. Otherwise FileComparisonFailureException does not provide link to file diff
+        val testDataPath = super.getTestDataPath()
+        try {
+            return File(testDataPath).getCanonicalPath()
+        }
+        catch (e: IOException) {
+            e.printStackTrace()
+            return testDataPath
+        }
+
+    }
 }