feat(DataView, ConstDataView)

test/index.js

@@ -1,11 +1,13 @@
+import { expect } from "vitest"
+
 export function filledDataView(bytes) {
   const ab = new ArrayBuffer(bytes.length)
   const dv = new DataView(ab)
-  
+
   for (let i = 0; i < bytes.length; i++) {
     dv.setInt8(i, bytes[i])
   }
-  
+
   return dv
 }
 
@@ -13,3 +15,22 @@ export function sizedDataView(length) {
   const ab = new ArrayBuffer(length)
   return new DataView(ab)
 }
+
+export function expectDataViewEqual(actual, expected) {
+  const actualBytes = new Uint8Array(actual.buffer, actual.byteOffset, actual.byteLength)
+  const expectedBytes = new Uint8Array(expected.buffer, expected.byteOffset, expected.byteLength)
+
+  if (actualBytes.length !== expectedBytes.length) {
+    throw new Error(`DataView length mismatch: ${actualBytes.length} !== ${expectedBytes.length}`)
+  }
+
+  for (let i = 0; i < actualBytes.length; i++) {
+    if (actualBytes[i] !== expectedBytes[i]) {
+      throw new Error(
+        `Byte mismatch at offset ${i}: 0x${actualBytes[i].toString(16)} !== 0x${expectedBytes[i].toString(16)}\n` +
+        `actual:   [${Array.from(actualBytes).map(byte => '0x' + byte.toString(16)).join(', ')}]\n` +
+        `expected: [${Array.from(expectedBytes).map(byte => '0x' + byte.toString(16)).join(', ')}]`
+      )
+    }
+  }
+}