tests: Add stack interaction test case

Makefile

@@ -6,7 +6,7 @@ EXEC            := exec
 # Test artifacts
 TEST_DIR        := tests
 TEST_OUT        := $(TEST_DIR)/all
-TEST_SRCS       := all.cpp types.cpp
+TEST_SRCS       := all.cpp types.cpp stack.cpp
 TEST_DEPS       := $(TEST_SRCS:%.cpp=$(TEST_DIR)/%.d)
 TEST_OBJS       := $(TEST_SRCS:%.cpp=$(TEST_DIR)/%.o)
 

tests/stack.cpp

@@ -0,0 +1,40 @@
+#include "catch.hpp"
+
+#include <lua.hpp>
+#include <luwra.hpp>
+
+int test_function_1(int a, int b) {
+	return a - b;
+}
+
+int test_function_2(int a, int b, int c) {
+	return a + b * c;
+}
+
+void test_function_3(int) {
+
+}
+
+TEST_CASE("Stack interaction") {
+	lua_State* state = luaL_newstate();
+
+	luwra::push(state, 1);
+	luwra::push(state, 2);
+	luwra::push(state, 4);
+
+	// Redundant function
+	luwra::apply(state, test_function_3);
+
+	// Absolute index
+	REQUIRE(luwra::apply(state, test_function_1) == -1);
+	REQUIRE(luwra::apply(state, 1, test_function_1) == -1);
+	REQUIRE(luwra::apply(state, test_function_2) == 9);
+	REQUIRE(luwra::apply(state, 1, test_function_2) == 9);
+
+	// Relative index
+	REQUIRE(luwra::apply(state, -2, test_function_1) == -2);
+	REQUIRE(luwra::apply(state, -3, test_function_1) == -1);
+	REQUIRE(luwra::apply(state, -3, test_function_2) == 9);
+
+	lua_close(state);
+}