fix(ext/kv): KvU64#valueOf and KvU64 inspect (#18656)

`new Deno.KvU64(1n) + 2n == 3n` is now true.

`new Deno.KvU64(1n)` is now inspected as `[Deno.KvU64: 1n]`
(`Object(1n)` is inspected as `[BigInt: 1n]`).

---------

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

1 files changed, 19 insertions, 7 deletions

diff --git a/cli/tests/unit/kv_test.ts b/cli/tests/unit/kv_test.ts
index 5a202fb0b..3a3476857 100644
--- a/cli/tests/unit/kv_test.ts
+++ b/cli/tests/unit/kv_test.ts
@@ -578,17 +578,29 @@ Deno.test("KvU64 underflow", () => {
   }, RangeError);
 });
 
-Deno.test("KvU64 frozen", () => {
+Deno.test("KvU64 unbox", () => {
   const a = new Deno.KvU64(1n);
-  assertThrows(() => {
-    // @ts-expect-error value is readonly
-    a.value = 2n;
-  }, TypeError);
+  assertEquals(a.value, 1n);
 });
 
-Deno.test("KvU64 unbox", () => {
+Deno.test("KvU64 unbox with valueOf", () => {
   const a = new Deno.KvU64(1n);
-  assertEquals(a.value, 1n);
+  assertEquals(a.valueOf(), 1n);
+});
+
+Deno.test("KvU64 auto-unbox", () => {
+  const a = new Deno.KvU64(1n);
+  assertEquals(a as unknown as bigint + 1n, 2n);
+});
+
+Deno.test("KvU64 toString", () => {
+  const a = new Deno.KvU64(1n);
+  assertEquals(a.toString(), "1");
+});
+
+Deno.test("KvU64 inspect", () => {
+  const a = new Deno.KvU64(1n);
+  assertEquals(Deno.inspect(a), "[Deno.KvU64: 1n]");
 });
 
 async function collect<T>(