Run build pipeline on both Windows, Ubuntu and Mac OS X (#431)

* Run build pipeline on both windows and ubuntu

* Fix weird path issue in main class resolver on Windows

* Add macos to build pipeline os list

* Prettify code fix for Windows test failure

Author: themkat

.github/workflows/build.yml

@@ -9,9 +9,10 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
         java: [ '11', '17' ]
     steps:
       - uses: actions/checkout@v3

server/src/main/kotlin/org/javacs/kt/resolve/ResolveMain.kt

@@ -1,5 +1,6 @@
 package org.javacs.kt.resolve
 
+import java.io.File
 import org.jetbrains.kotlin.fileClasses.JvmFileClassUtil
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.psi.KtNamedFunction
@@ -15,7 +16,7 @@ fun resolveMain(file: CompiledFile): Map<String,Any> {
 
     findTopLevelMainFunction(parsedFile)?.let { mainFunction ->
         // the KtFiles name is weird. Full path. This causes the class to have full path in name as well. Correcting to top level only
-        parsedFile.name = parsedFile.name.partitionAroundLast("/").second.substring(1)
+        parsedFile.name = parsedFile.name.partitionAroundLast(File.separator).second.substring(1)
 
         return mapOf(
             "mainClass" to JvmFileClassUtil.getFileClassInfoNoResolve(parsedFile).facadeClassFqName.asString(),