diff --git a/backend.native/tests/build.gradle b/backend.native/tests/build.gradle
index c883e1e2dba..21924a72ced 100644
--- a/backend.native/tests/build.gradle
+++ b/backend.native/tests/build.gradle
@@ -172,12 +172,13 @@ task hello1(type: RunKonanTest) {
     source = "runtime/basic/hello1.kt"
 }
 
-/* TODO: enable, once calling plus operator is implemented.
+/*
 task hello2(type: RunKonanTest) {
-    goldValue = "Hello World"
+    goldValue = "you entered 'Hello World'"
     testData = "Hello World"
     source = "runtime/basic/hello2.kt"
-} */
+}
+*/
 
 /* TODO: enable, once can call toString() on Int.
 task hello3(type: RunKonanTest) {
diff --git a/backend.native/tests/codegen/function/eqeq-test.c b/backend.native/tests/codegen/function/eqeq-test.c
new file mode 100644
index 00000000000..0365823c3ce
--- /dev/null
+++ b/backend.native/tests/codegen/function/eqeq-test.c
@@ -0,0 +1,20 @@
+#include <stdint.h>
+extern void *resolve_symbol(const char*);
+
+int
+run_test() {
+  int (*eqeqB)(uint8_t, uint8_t) = resolve_symbol("kfun:eqeqB");
+  int (*eqeqS)(int16_t, int16_t) = resolve_symbol("kfun:eqeqS");
+  int (*eqeqI)(int    , int    ) = resolve_symbol("kfun:eqeqI");
+  int (*eqeqL)(int64_t, int64_t) = resolve_symbol("kfun:eqeqL");
+  int (*eqeqF)(float  , float  ) = resolve_symbol("kfun:eqeqF");
+  int (*eqeqD)(double , double ) = resolve_symbol("kfun:eqeqD");
+  if (!eqeqB(3   , 3   )) return 1;
+  if (!eqeqS(3   , 3   )) return 1;
+  if (!eqeqI(3   , 3   )) return 1;
+  if (!eqeqL(3ll , 3ll )) return 1;
+  if (!eqeqF(3.0f, 3.0f)) return 1;
+  if (!eqeqD(3.0 , 3.0 )) return 1;
+
+  return 0;
+}
diff --git a/backend.native/tests/codegen/function/eqeq.kt b/backend.native/tests/codegen/function/eqeq.kt
new file mode 100644
index 00000000000..cc80c896970
--- /dev/null
+++ b/backend.native/tests/codegen/function/eqeq.kt
@@ -0,0 +1,8 @@
+fun eqeqB(a:Byte,   b:Byte  ) = a == b
+fun eqeqS(a:Short,  b:Short ) = a == b
+fun eqeqI(a:Int,    b:Int   ) = a == b
+fun eqeqL(a:Long,   b:Long  ) = a == b
+fun eqeqF(a:Float,  b:Float ) = a == b
+fun eqeqD(a:Double, b:Double) = a == b
+
+//fun eqeqStr(a:String, b:String) = a == b
diff --git a/backend.native/tests/codegen/function/sum-test.c b/backend.native/tests/codegen/function/sum-test.c
index 2658fe58131..d378419609f 100644
--- a/backend.native/tests/codegen/function/sum-test.c
+++ b/backend.native/tests/codegen/function/sum-test.c
@@ -1,10 +1,22 @@
+#include <stdint.h>
 extern void *resolve_symbol(const char*);
 
 int
 run_test() {
-  int (*sum)(int, int) = resolve_symbol("kfun:sum");
-  
-  if (sum(2, 3) != 5) return 1;
+  int     (*sumIB)(int, uint8_t) = resolve_symbol("kfun:sumIB");
+  int     (*sumIS)(int, int16_t) = resolve_symbol("kfun:sumIS");
+  int     (*sumII)(int, int    ) = resolve_symbol("kfun:sumII");
+  int64_t (*sumIL)(int, int64_t) = resolve_symbol("kfun:sumIL");
+  float   (*sumIF)(int, float  ) = resolve_symbol("kfun:sumIF");
+  double  (*sumID)(int, double ) = resolve_symbol("kfun:sumID");
+  double  (*modID)(int, double ) = resolve_symbol("kfun:modID");
+  if (sumIB(2, 3)    != 5)    return 1;
+  if (sumIS(2, 3)    != 5)    return 1;
+  if (sumII(2, 3)    != 5)    return 1;
+  if (sumIL(2, 3l)   != 5l)   return 1;
+  if (sumIF(2, 3.0f) != 5.0f) return 1;
+  if (sumID(2, 3.0)  != 5.0)  return 1;
+  if (modID(5, 3.0)  != 2.0)  return 1;
 
   return 0;
 }
diff --git a/backend.native/tests/codegen/function/sum.kt b/backend.native/tests/codegen/function/sum.kt
index 38215fdce2d..ee578b707a0 100644
--- a/backend.native/tests/codegen/function/sum.kt
+++ b/backend.native/tests/codegen/function/sum.kt
@@ -1 +1,8 @@
-fun sum(a:Int, b:Int) = a + b
\ No newline at end of file
+fun sumIB(a:Int, b:Byte  ) = a + b
+fun sumIS(a:Int, b:Short ) = a + b
+fun sumII(a:Int, b:Int   ) = a + b
+fun sumIL(a:Int, b:Long  ) = a + b
+fun sumIF(a:Int, b:Float ) = a + b
+fun sumID(a:Int, b:Double) = a + b
+
+fun modID(a:Int, b:Double) = a % b
\ No newline at end of file
diff --git a/backend.native/tests/codegen/function/sum_mixed.kt b/backend.native/tests/codegen/function/sum_mixed.kt
new file mode 100644
index 00000000000..66d23047854
--- /dev/null
+++ b/backend.native/tests/codegen/function/sum_mixed.kt
@@ -0,0 +1 @@
+fun sum(a:Float, b:Int) = a + b
\ No newline at end of file