[Native] Always enable assertions in KonanLocalTest

kotlin-native/backend.native/tests/build.gradle

@@ -1667,6 +1667,10 @@ task lateinit_innerIsInitialized(type: KonanLocalTest) {
     source = "codegen/lateinit/innerIsInitialized.kt"
 }
 
+task sanity_assertions_enabled_for_local_tests(type: KonanLocalTest) {
+    source = "sanity/assertions_enabled_for_local_tests.kt"
+}
+
 task kclass0(type: KonanLocalTest) {
     source = "codegen/kclass/kclass0.kt"
 }
@@ -5215,7 +5219,7 @@ private void configureStdlibTest(KonanGTest task, boolean inWorker) {
  * Builds tests into a single binary with TestRunner
  */
 task buildKonanTests { t ->
-    def compileList = [ "codegen", "datagen", "lower", "runtime", "serialization" ]
+    def compileList = [ "codegen", "datagen", "lower", "runtime", "serialization", "sanity" ]
 
     // These tests should not be built into the TestRunner's test executable
     def excludeList = [ "codegen/inline/returnLocalClassFromBlock.kt" ]
@@ -5236,6 +5240,8 @@ task buildKonanTests { t ->
         program('localTest', targets: [target.name]) {
             srcFiles sources
             baseDir testOutputLocal
+            extraOpts '-ea' // Without this option assertions would remain inactive.
+            extraOpts '-g' // To include line numbers in stack trace.
             extraOpts '-tr'
             extraOpts '-Xverify-ir'
             extraOpts project.globalTestArgs

kotlin-native/backend.native/tests/sanity/assertions_enabled_for_local_tests.kt

@@ -0,0 +1,17 @@
+package sanity.assertions_enabled
+
+import kotlin.test.Test
+
+// Just to make sure that assertions are enabled for `KonanLocalTest`s.
+@Test fun runTest() {
+    main(emptyArray<String>())
+}
+
+fun main(args: Array<String>) {
+    try {
+        assert(false) // Should throw AssertionError.
+        throw Error("Assertions are disabled. Please make sure the tests were compiled with '-ea' option.") // Normally unreachable line.
+    } catch (e: AssertionError) {
+        // That's OK.
+    }
+}