unit test introduced:

User should create <test-name>-test.c file in the following manner:
> cat codegen/function/sum-test.c
extern void *resolve_symbol(const char*);

int
run_test() {
  int (*sum)(int, int) = resolve_symbol("kfun:sum");

  if (sum(2, 3) != 5) return 1;

  return 0;
}
and add <test-name> to the TESTS variable in the Makefile
to run tests:
> make clean run
Note: failing tests should return no zero values.

backend.native/tests/Makefile

@@ -0,0 +1,43 @@
+TESTS := sum
+
+BIN_TESTS=$(foreach t, ${TESTS},${t}_test)
+
+VPATH=codegen/function
+
+LLC=llc-mp-3.8
+CC=clang-mp-3.8
+JAVA=java
+
+TOP=../..
+RUNTIME=${TOP}/runtime
+BACKEND=${TOP}/backend.native
+BACKEND_CLASSES=${TOP}/backend.native/build/classes
+KOTLIN_DIST=${BACKEND}/kotlin-ir/dist
+KOTLIN_NATIVE_CLASSPATH=${BACKEND_CLASSES}/bc_frontend:${BACKEND_CLASSES}/cli_bc:${BACKEND_CLASSES}/compiler:${KOTLIN_DIST}/kotlinc/lib/kotlin-reflect.jar:${KOTLIN_DIST}kotlinc/lib/kotlin-stdlib.jar:${KOTLIN_DIST}/kotlinc/lib/kotlin-compiler.jar:${KOTLIN_DIST}/kotlinc/lib/kotlin-runtime.jar:${TOP}/Interop/Runtime/build/classes/main
+
+
+define PROTO
+$(1)_test: main.c $1-test.c $1.S
+	$(CC) -o $$@ $$^
+
+${1}_run:${1}_test
+	./${1}_test
+endef
+
+$(foreach test,${TESTS},$(eval $(call PROTO,$(test))))
+
+all:${BIN_TESTS}
+
+run:$(foreach test,${TESTS},${test}_run)
+
+clean:
+	${RM} *.o *.S *.BCkt ${BIN_TESTS}
+
+
+%.S:%.BCkt
+	${LLC} -o $@ $<
+
+
+%.BCkt:%.kt
+	${JAVA} -cp ${KOTLIN_NATIVE_CLASSPATH} -Djava.library.path=${BACKEND}/build/nativelibs org.jetbrains.kotlin.cli.bc.K2NativeKt -output $@ -runtime ${RUNTIME}/build/runtime.bc $<
+

backend.native/tests/codegen/function/sum-test.c

@@ -0,0 +1,10 @@
+extern void *resolve_symbol(const char*);
+
+int
+run_test() {
+  int (*sum)(int, int) = resolve_symbol("kfun:sum");
+  
+  if (sum(2, 3) != 5) return 1;
+
+  return 0;
+}

backend.native/tests/main.c

@@ -0,0 +1,19 @@
+#include <dlfcn.h>
+#include <stdio.h>
+/**
+ * > llc-mp-3.8 b.out -o b.S
+ * > /opt/local/libexec/llvm-3.8/bin/clang main.c b.S -o sum-test
+ */
+
+extern int run_test();
+
+void * resolve_symbol(char *name) {
+  /* here we can add here some magic to resolve symbols in kotlin native*/
+  return dlsym(RTLD_SELF, name);
+}
+    
+
+int
+main() {
+  return run_test();
+}