First pass at bufio.read tests.

Original: https://github.com/denoland/deno_std/commit/1eb57aa3948caf88e9064defc15e076b8a46fbd2

1 files changed, 12 insertions, 1 deletions

diff --git a/util.ts b/util.ts
index decf4d043..84ef8b5a8 100644
--- a/util.ts
+++ b/util.ts
@@ -1,6 +1,17 @@
-
 export function assert(cond: boolean, msg = "assert") {
   if (!cond) {
     throw Error(msg);
   }
 }
+
+// `off` is the offset into `dst` where it will at which to begin writing values
+// from `src`.
+// Returns the number of bytes copied.
+export function copyBytes(dst: Uint8Array, src: Uint8Array, off = 0): number {
+  const r = dst.byteLength - off;
+  if (src.byteLength > r) {
+    src = src.subarray(0, r);
+  }
+  dst.set(src, off);
+  return src.byteLength;
+}