[K/N] Move cinterop tests from standalone to codegen/box

^KT-61259

compiler/testData/codegen/box/cinterop/toKString.kt

@@ -0,0 +1,29 @@
+// TARGET_BACKEND: NATIVE
+// MODULE: cinterop
+// FILE: toKString.def
+---
+const char* empty() { return ""; }
+const char* foo() { return "foo"; }
+const char* kuku() { return "куку"; }
+const char* invalid_utf8() { return "\x85\xAF"; }
+const char* zero_in_the_middle() { return "before zero\0after zero"; }
+
+
+// MODULE: main(cinterop)
+// FILE: main.kt
+@file:OptIn(kotlinx.cinterop.ExperimentalForeignApi::class)
+
+import toKString.*
+import kotlinx.cinterop.*
+import kotlin.native.*
+import kotlin.test.*
+
+fun box(): String {
+    assertEquals("", empty()!!.toKStringFromUtf8())
+    assertEquals("foo", foo()!!.toKStringFromUtf8())
+    assertEquals("куку", kuku()!!.toKStringFromUtf8())
+    assertEquals("\uFFFD\uFFFD", invalid_utf8()!!.toKStringFromUtf8())
+    assertEquals("before zero", zero_in_the_middle()!!.toKStringFromUtf8())
+
+    return "OK"
+}