diff --git a/backend/src/controllers/receipts.c b/backend/src/controllers/receipts.c
index 25c9eb1..e13ff28 100644
--- a/backend/src/controllers/receipts.c
+++ b/backend/src/controllers/receipts.c
@@ -101,7 +101,6 @@ void route_get_receipts_all(HttpCtx* ctx)
 
     String receipts_str;
     string_construct(&receipts_str);
-    string_push_str(&receipts_str, "");
     for (size_t i = 0; i < receipts.size; ++i) {
         if (i != 0) {
             string_pushf(&receipts_str, ",");
diff --git a/backend/src/util/str.c b/backend/src/util/str.c
index 2c21382..6aa5531 100644
--- a/backend/src/util/str.c
+++ b/backend/src/util/str.c
@@ -52,27 +52,64 @@ StrSlice str_split_next(StrSplitter* splitter)
     return slice;
 }
 
-void string_push_str(String* string, const char* str)
+int string_construct(String* string)
 {
-    for (size_t i = 0; i < strlen(str); ++i) {
-        string_data_push(string, str[i]);
+    int res = string_data_construct(string);
+    if (res != 0) {
+        return res;
     }
-
-    string_data_push(string, '\0');
-    string->size -= 1;
+    // NOTE: Vec is assumed to be initialized with atleast 1 allocated byte.
+    string->data[0] = '\0';
+    return 0;
 }
 
-void string_push_fmt_va(String* string, const char* fmt, ...)
+void string_destroy(String* string)
+{
+    string_data_destroy(string);
+}
+
+int string_push(String* string, char value)
+{
+    int res = string_data_push(string, value);
+    if (res != 0)
+        return res;
+    res = string_data_push(string, '\0');
+    if (res != 0)
+        return res;
+    string->size -= 1;
+    return 0;
+}
+
+int string_push_str(String* string, const char* str)
+{
+    for (size_t i = 0; i < strlen(str); ++i) {
+        int res = string_data_push(string, str[i]);
+        if (res != 0)
+            return res;
+    }
+
+    int res = string_data_push(string, '\0');
+    if (res != 0)
+        return res;
+    string->size -= 1;
+    return 0;
+}
+
+int string_push_fmt_va(String* string, const char* fmt, ...)
 {
     va_list args1;
     va_start(args1, fmt);
     va_list args2;
     va_copy(args2, args1);
-    char buf[1 + vsnprintf(NULL, 0, fmt, args1)];
+
+    size_t buffer_size = (size_t)vsnprintf(NULL, 0, fmt, args1) + 1;
+    char* buf = malloc(buffer_size);
     va_end(args1);
-    vsnprintf(buf, sizeof buf, fmt, args2);
+
+    vsnprintf(buf, buffer_size, fmt, args2);
     va_end(args2);
-    string_push_str(string, buf);
+
+    return string_push_str(string, buf);
 }
 
 char* string_copy(const String* string)
diff --git a/backend/src/util/str.h b/backend/src/util/str.h
index bd86953..2fbce41 100644
--- a/backend/src/util/str.h
+++ b/backend/src/util/str.h
@@ -27,8 +27,11 @@ StrSlice str_split_next(StrSplitter* splitter);
 
 DEFINE_VEC(char, String, string_data)
 
-void string_push_str(String* string, const char* str);
-void string_push_fmt_va(String* string, const char* fmt, ...);
+int string_construct(String* string);
+void string_destroy(String* string);
+int string_push(String* string, char value);
+int string_push_str(String* string, const char* str);
+int string_push_fmt_va(String* string, const char* fmt, ...);
 char* string_copy(const String* string);
 
 #define string_pushf(STRING, ...) string_push_fmt_va(STRING, __VA_ARGS__)
diff --git a/backend/test/test.ts b/backend/test/test.ts
index 2551656..8945894 100644
--- a/backend/test/test.ts
+++ b/backend/test/test.ts
@@ -45,7 +45,7 @@ Deno.test("test backend", async (t) => {
             { "Session-Token": token! },
         );
 
-        // console.log(sessionUserRes.user);
+        //console.log(sessionUserRes.user);
         assertEquals(sessionUserRes.ok, true);
     });
 
@@ -58,7 +58,7 @@ Deno.test("test backend", async (t) => {
             { "Session-Token": token! },
         );
 
-        // console.log(sessionUserRes);
+        //console.log(sessionUserRes);
         assertEquals(sessionUserRes.ok, true);
     });
 
@@ -81,6 +81,20 @@ Deno.test("test backend", async (t) => {
 async function testCartsAndReceipts(t: Deno.TestContext, token: string) {
     let receiptId: number | undefined = undefined;
 
+    await t.step("test /api/receipts/all", async () => {
+        const res = await get<{
+            ok: boolean;
+            receipts: { timestamp: string }[];
+        }>(
+            `/api/receipts/all`,
+            { "Session-Token": token },
+        );
+
+        // console.log(res);
+        assertEquals(res.ok, true);
+        assertEquals(res.receipts.length, 0);
+    });
+
     const user1 = await sessionUser(token);
 
     await t.step("test /api/carts/purchase", async () => {
@@ -88,13 +102,14 @@ async function testCartsAndReceipts(t: Deno.TestContext, token: string) {
             "/api/carts/purchase",
             {
                 items: [
-                    { product_id: 1, amount: 2 },
-                    { product_id: 2, amount: 5 },
+                    { product_id: 1, amount: 5 },
+                    { product_id: 2, amount: 2 },
                 ],
             },
             { "Session-Token": token },
         );
 
+        //console.log(res);
         assertEquals(res.ok, true);
         receiptId = res.receipt_id;
     });
@@ -103,7 +118,7 @@ async function testCartsAndReceipts(t: Deno.TestContext, token: string) {
     assertNotEquals(user1.balance_dkk_cent, user2.balance_dkk_cent);
     assertEquals(
         user1.balance_dkk_cent - user2.balance_dkk_cent,
-        1195 * 2 + 1295 * 5,
+        1195 * 5 + 1295 * 2,
     );
 
     if (!receiptId) {