Enable new inference explicitly for MPP tests with type refinement

idea/tests/org/jetbrains/kotlin/idea/multiplatform/multiPlatformSetup.kt

@@ -94,7 +94,8 @@ fun AbstractMultiModuleTest.doSetup(projectModel: ProjectResolveModel) {
             platform,
             implementedModuleNames = resolveModule.dependencies.filter { it.kind == ResolveDependency.Kind.DEPENDS_ON }.map { it.to.name }
         )
-        ideaModule.enableMultiPlatform()
+        // New inference is enabled here as these tests are using type refinement feature that is working only along with NI
+        ideaModule.enableMultiPlatform(additionalCompilerArguments = "-Xnew-inference")
     }
 }
 

idea/tests/org/jetbrains/kotlin/idea/stubs/AbstractMultiModuleTest.kt

@@ -109,12 +109,12 @@ abstract class AbstractMultiModuleTest : DaemonAnalyzerTestCase() {
         }, this, kind)
     }
 
-    fun Module.enableMultiPlatform() {
+    fun Module.enableMultiPlatform(additionalCompilerArguments: String = "") {
         createFacet()
         val facetSettings = KotlinFacetSettingsProvider.getInstance(project).getInitializedSettings(this)
         facetSettings.useProjectSettings = false
         facetSettings.compilerSettings = CompilerSettings().apply {
-            additionalArguments += " -Xmulti-platform -XXtype-refinement"
+            additionalArguments += " -Xmulti-platform $additionalCompilerArguments"
         }
     }