Wrote a test for shared library linking

src/GC/tests/extern_lib.cpp

@@ -0,0 +1,52 @@
+#include <cstring>
+#include <iostream>
+
+#include "heap.hpp"
+
+// using namespace std;
+
+// GC::Heap *singleton_test();
+// void init_gc(GC::Heap *heap);
+// void frame_test(GC::Heap *heap);
+
+GC::Heap *singleton_test() {
+    std::cout << "TESTING SINGLETON INSTANCES" << std::endl;
+    std::cout << "===========================" << std::endl;
+    std::cout << "Call 1:\t" << GC::Heap::the() << std::endl;
+    GC::Heap *heap = GC::Heap::the();
+    std::cout << "Call 2:\t" << heap << std::endl;
+    std::cout << "===========================" << std::endl;
+    return heap;
+}
+
+void init_gc(GC::Heap *heap){
+    std::cout << "\n\n   INITIALIZING THE HEAP" << std::endl;
+    std::cout << "===========================" << std::endl;
+    heap->init();
+    std::cout << "===========================" << std::endl;
+}
+
+void frame_test(GC::Heap *heap) {
+    std::cout << "\n\n  TESTING FRAME ADDRESSES" << std::endl;
+    std::cout << "===========================" << std::endl;
+
+#pragma clang diagnostic ignored "-Wframe-address"
+    auto curr_frame = reinterpret_cast<uintptr_t *>(__builtin_frame_address(0));
+    std::cout << "Current stack frame:\t" << curr_frame << std::endl;
+#pragma clang diagnostic ignored "-Wframe-address"
+    auto prev_frame = reinterpret_cast<uintptr_t *>(__builtin_frame_address(1));
+    std::cout << "Previous stack frame:\t" << prev_frame << std::endl;
+
+    heap->check_init();
+    
+    std::cout << "===========================" << std::endl;
+}
+
+int main() {
+    auto heap = singleton_test();
+
+    init_gc(heap);
+    frame_test(heap);
+
+    return 0;
+}