Add unit-test for malloc(...) and free(...)

src/usr/local/src/test-stdlib.cpp

@@ -1,3 +1,4 @@
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -47,6 +48,53 @@ void test_ftoa() {
     ASSERT_TRUE(std::strcmp(buffer, "0.15") == 0);
 }
 
+void test_malloc_free() {
+    // we don't want to test to be dependent on the internal
+    // implementation of malloc and free. So, we are ensuring
+    // no overlapping memory is being allocated.
+
+    const int test_order[] = {
+        64,   // [0] allocate 64 bytes
+        128,  // [1] allocate 128 bytes
+        -0,   // [2] test memory and deallocate 64 bytes
+        1024, // [3] allocate 1024 bytes
+        -1,   // [4] test memory and deallocate 128 bytes
+        100,  // [5] allocate 100 bytes, it could get allocated in freed space
+        -5,   // [6] test memory and deallocate 100 bytes
+        -3    // [7] test memory and deallocate 1024 bytes
+    };
+    std::uint8_t *memory_track[sizeof(test_order) / sizeof(test_order[0])];
+
+    for (std::uint8_t i = 0; i < sizeof(test_order) / sizeof(test_order[0]);
+         i++) {
+        int op = test_order[i];
+        if (op > 0) {
+            // allocate memory
+            memory_track[i] = (std::uint8_t *)std::malloc(op);
+
+            // put data bytes marker... in allocated memory
+            const std::uint8_t marker = i;
+            std::memset(memory_track[i], marker, test_order[i]);
+        } else {
+            int track_id = -op;
+
+            // test memory
+            const std::uint8_t marker = track_id;
+            bool is_track_memory_good = true;
+            for (int j = 0; j < test_order[track_id]; j++) {
+                if (memory_track[track_id][j] != marker) {
+                    is_track_memory_good = false;
+                    break;
+                }
+            }
+            ASSERT_TRUE(is_track_memory_good);
+
+            // free memory
+            std::free(memory_track[track_id]);
+        }
+    }
+}
+
 int main(int argc, char *argv[]) {
     TEST_INIT();
 
@@ -56,6 +104,7 @@ int main(int argc, char *argv[]) {
     RUN_TEST(test_atoi);
     RUN_TEST(test_itoa);
     RUN_TEST(test_ftoa);
+    RUN_TEST(test_malloc_free);
 
     TEST_SUMMARY();
     return 0;