feat(hash-stream-node): add readableStreamHasher (#3088)

Author: trivikr

packages/hash-stream-node/README.md

@@ -3,9 +3,7 @@
 [![NPM version](https://img.shields.io/npm/v/@aws-sdk/hash-stream-node/latest.svg)](https://www.npmjs.com/package/@aws-sdk/hash-stream-node)
 [![NPM downloads](https://img.shields.io/npm/dm/@aws-sdk/hash-stream-node.svg)](https://www.npmjs.com/package/@aws-sdk/hash-stream-node)
 
-A utility for calculating the hash of Node.JS readable streams. This package is
-currently only compatible with file streams, as no other stream type can be
-replayed.
+A utility for calculating the hash of Node.JS readable streams.
 
 > An internal package
 

packages/hash-stream-node/src/index.ts

@@ -1 +1,2 @@
 export * from "./fileStreamHasher";
+export * from "./readableStreamHasher";

packages/hash-stream-node/src/readableStreamHasher.spec.ts

@@ -0,0 +1,140 @@
+import { Hash } from "@aws-sdk/types";
+import { Readable, Writable, WritableOptions } from "stream";
+
+import { HashCalculator } from "./HashCalculator";
+import { readableStreamHasher } from "./readableStreamHasher";
+
+jest.mock("./HashCalculator");
+
+describe(readableStreamHasher.name, () => {
+  const mockDigest = jest.fn();
+  const mockHashCtor = jest.fn().mockImplementation(() => ({
+    update: jest.fn(),
+    digest: mockDigest,
+  }));
+
+  const mockHashCalculatorWrite = jest.fn();
+  const mockHashCalculatorEnd = jest.fn();
+
+  const mockHash = new Uint8Array(Buffer.from("mockHash"));
+
+  class MockHashCalculator extends Writable {
+    constructor(public readonly hash: Hash, public readonly mockWrite, public readonly mockEnd) {
+      super();
+    }
+
+    _write(chunk: Buffer, encoding: string, callback: (err?: Error) => void) {
+      this.mockWrite(chunk);
+      callback();
+    }
+
+    end() {
+      this.mockEnd();
+      super.end();
+    }
+  }
+
+  beforeEach(() => {
+    (HashCalculator as unknown as jest.Mock).mockImplementation(
+      (hash) => new MockHashCalculator(hash, mockHashCalculatorWrite, mockHashCalculatorEnd)
+    );
+    mockDigest.mockResolvedValue(mockHash);
+  });
+
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it("computes hash for a readable stream", async () => {
+    const readableStream = new Readable({
+      read: (size) => {},
+    });
+    const hashPromise = readableStreamHasher(mockHashCtor, readableStream);
+
+    // @ts-ignore Property '_readableState' does not exist on type 'Readable'.
+    const { pipesCount } = readableStream._readableState;
+    expect(pipesCount).toEqual(1);
+
+    const mockDataChunks = ["Hello", "World"];
+    setTimeout(() => {
+      mockDataChunks.forEach((chunk) => readableStream.emit("data", chunk));
+      readableStream.emit("end");
+    }, 100);
+
+    expect(await hashPromise).toEqual(mockHash);
+    expect(mockHashCalculatorWrite).toHaveBeenCalledTimes(mockDataChunks.length);
+    mockDataChunks.forEach((chunk, index) =>
+      expect(mockHashCalculatorWrite).toHaveBeenNthCalledWith(index + 1, Buffer.from(chunk))
+    );
+    expect(mockDigest).toHaveBeenCalledTimes(1);
+    expect(mockHashCalculatorEnd).toHaveBeenCalledTimes(1);
+  });
+
+  it("throws error if readable stream throws error", async () => {
+    const readableStream = new Readable({
+      read: (size) => {},
+    });
+    const hashPromise = readableStreamHasher(mockHashCtor, readableStream);
+
+    const mockError = new Error("error");
+    setTimeout(() => {
+      readableStream.emit("error", mockError);
+    }, 100);
+
+    try {
+      await hashPromise;
+      fail(`should throw error ${mockError}`);
+    } catch (error) {
+      expect(error).toEqual(mockError);
+      expect(mockHashCalculatorEnd).toHaveBeenCalledTimes(1);
+    }
+  });
+
+  it("throws error if HashCalculator throws error", async () => {
+    const mockHashCalculator = new MockHashCalculator(
+      mockHashCtor as any,
+      mockHashCalculatorWrite,
+      mockHashCalculatorEnd
+    );
+    (HashCalculator as unknown as jest.Mock).mockImplementation((hash) => mockHashCalculator);
+
+    const readableStream = new Readable({
+      read: (size) => {},
+    });
+    const hashPromise = readableStreamHasher(mockHashCtor, readableStream);
+
+    const mockError = new Error("error");
+    setTimeout(() => {
+      mockHashCalculator.emit("error", mockError);
+    }, 100);
+
+    try {
+      await hashPromise;
+      fail(`should throw error ${mockError}`);
+    } catch (error) {
+      expect(error).toEqual(mockError);
+    }
+  });
+
+  it("throws error if hash.digest() throws error", async () => {
+    const readableStream = new Readable({
+      read: (size) => {},
+    });
+    const hashPromise = readableStreamHasher(mockHashCtor, readableStream);
+
+    setTimeout(() => {
+      readableStream.emit("end");
+    }, 100);
+
+    const mockError = new Error("error");
+    mockDigest.mockRejectedValue(mockError);
+
+    try {
+      await hashPromise;
+      fail(`should throw error ${mockError}`);
+    } catch (error) {
+      expect(error).toEqual(mockError);
+      expect(mockHashCalculatorEnd).toHaveBeenCalledTimes(1);
+    }
+  });
+});

packages/hash-stream-node/src/readableStreamHasher.ts

@@ -0,0 +1,22 @@
+import { HashConstructor, StreamHasher } from "@aws-sdk/types";
+import { Readable } from "stream";
+
+import { HashCalculator } from "./HashCalculator";
+
+export const readableStreamHasher: StreamHasher<Readable> = (hashCtor: HashConstructor, readableStream: Readable) => {
+  const hash = new hashCtor();
+  const hashCalculator = new HashCalculator(hash);
+  readableStream.pipe(hashCalculator);
+
+  return new Promise((resolve, reject) => {
+    readableStream.on("error", (err: Error) => {
+      // if the source errors, the destination stream needs to manually end
+      hashCalculator.end();
+      reject(err);
+    });
+    hashCalculator.on("error", reject);
+    hashCalculator.on("finish", () => {
+      hash.digest().then(resolve).catch(reject);
+    });
+  });
+};