fix(core/interaction-output): return an ArrayBuffer in the arrayBuffer method

Author: relu91

packages/core/src/content.ts

@@ -25,7 +25,7 @@ export class Content {
         this.body = body;
     }
 
-    toBuffer(): Promise<Buffer> {
+    toBuffer(): Promise<Buffer<ArrayBuffer>> {
         return ProtocolHelpers.readStreamFully(this.body);
     }
 }

packages/core/src/interaction-output.ts

@@ -37,6 +37,7 @@ addFormats(ajv);
 export class InteractionOutput implements WoT.InteractionOutput {
     #content: Content;
     #value: unknown;
+    #valueBuffer?: Buffer<ArrayBuffer>;
     #buffer?: ArrayBuffer;
     #stream?: ReadableStream;
     dataUsed: boolean;
@@ -73,11 +74,16 @@ export class InteractionOutput implements WoT.InteractionOutput {
             throw new Error("Can't read the stream once it has been already used");
         }
 
-        const data = await this.#content.toBuffer();
+        const data = this.#valueBuffer ?? (await this.#content.toBuffer());
         this.dataUsed = true;
-        // this.#buffer = new Uint8Array(data).buffer
-        this.#buffer = data as unknown as ArrayBuffer;
+        const isPooled = data.byteLength < 4096 && data.buffer.byteLength > data.byteLength;
 
+        if (isPooled) {
+            this.#buffer = data.buffer.slice(data.byteOffset, data.byteOffset + data.byteLength);
+        } else {
+            this.#buffer = data.buffer;
+        }
+        //this.#buffer = data as unknown as ArrayBuffer
         return this.#buffer;
     }
 
@@ -121,8 +127,7 @@ export class InteractionOutput implements WoT.InteractionOutput {
         // read fully the stream
         const bytes = await this.#content.toBuffer();
         this.dataUsed = true;
-        // this.#buffer = new Uint8Array(bytes).buffer;
-        this.#buffer = bytes as unknown as ArrayBuffer;
+        this.#valueBuffer = bytes;
 
         const json = ContentSerdes.get().contentToValue({ type: this.#content.type, body: bytes }, this.schema);
 

packages/core/src/protocol-helpers.ts

@@ -233,8 +233,8 @@ export default class ProtocolHelpers {
         return result;
     }
 
-    static readStreamFully(stream: NodeJS.ReadableStream): Promise<Buffer> {
-        return new Promise<Buffer>((resolve, reject) => {
+    static readStreamFully(stream: NodeJS.ReadableStream): Promise<Buffer<ArrayBuffer>> {
+        return new Promise((resolve, reject) => {
             if (stream != null) {
                 const chunks: Array<unknown> = [];
                 stream.on("data", (data) => chunks.push(data));

packages/core/test/interaction-output-test.ts

@@ -34,7 +34,9 @@ class InteractionOutputTests {
 
         const out = new InteractionOutput(content, {});
         const result = await out.arrayBuffer();
-        expect(result).be.deep.equals(Buffer.from([1, 2, 3]));
+
+        expect(result).instanceOf(ArrayBuffer);
+        expect(Buffer.from(result)).be.deep.equals(Buffer.from([1, 2, 3]));
     }
 
     @test async "should be readable with Streams"() {