Add some simple tests

tests/test_vector.c

@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include "../vector.h"
+
+int main(void) {
+    vector_t* vec = vector_create(sizeof(int));
+    if (!vec) {
+        fprintf(stderr, "Failed to create vector\n");
+        return 1;
+    }
+
+    for (int i = 0; i < 10; ++i) {
+        if (vector_push_back(vec, &i) != 0) {
+            fprintf(stderr, "Failed to push back %d\n", i);
+            vector_destroy(&vec);
+            return 1;
+        }
+    }
+
+    for (size_t i = 0; i < vector_size(vec); ++i) {
+        int* value = (int*)vector_get(vec, i);
+        if (value) {
+            printf("vec[%zu] = %d\n", i, *value);
+        } else {
+            fprintf(stderr, "Failed to get value at index %zu\n", i);
+        }
+    }
+
+    vector_destroy(&vec);
+    if (vec != NULL) {
+        fprintf(stderr, "Vector pointer was not set to NULL after destruction\n");
+        return 1;
+    }
+    return 0;
+}