add karma test for checksum stream

Author: kuhe

packages/util-stream/karma.conf.js

@@ -3,7 +3,14 @@
 module.exports = function (config) {
   config.set({
     frameworks: ["jasmine", "karma-typescript"],
-    files: ["src/getAwsChunkedEncodingStream.browser.ts", "src/getAwsChunkedEncodingStream.browser.spec.ts"],
+    files: [
+      "src/checksum/createChecksumStream.browser.spec.ts",
+      "src/checksum/createChecksumStream.browser.ts",
+      "src/getAwsChunkedEncodingStream.browser.spec.ts",
+      "src/getAwsChunkedEncodingStream.browser.ts",
+      "src/headStream.browser.ts",
+      "src/stream-type-check.ts",
+    ],
     exclude: ["**/*.d.ts"],
     preprocessors: {
       "**/*.ts": "karma-typescript",

packages/util-stream/src/checksum/createChecksumStream.browser.spec.ts

@@ -0,0 +1,89 @@
+import { Checksum } from "@smithy/types";
+import { toBase64 } from "@smithy/util-base64";
+import { toUtf8 } from "@smithy/util-utf8";
+
+import { headStream } from "../headStream.browser";
+import { createChecksumStream } from "./createChecksumStream.browser";
+import { ChecksumStream as ChecksumStreamWeb } from "./createChecksumStream.browser";
+
+describe("Checksum streams", () => {
+  /**
+   * Hash "algorithm" that appends all data together.
+   */
+  class Appender implements Checksum {
+    public hash = "";
+    async digest(): Promise<Uint8Array> {
+      return Buffer.from(this.hash);
+    }
+    reset(): void {
+      throw new Error("Function not implemented.");
+    }
+    update(chunk: Uint8Array): void {
+      this.hash += toUtf8(chunk);
+    }
+  }
+
+  const canonicalData = new Uint8Array("abcdefghijklmnopqrstuvwxyz".split("").map((_) => _.charCodeAt(0)));
+
+  const canonicalUtf8 = toUtf8(canonicalData);
+  const canonicalBase64 = toBase64(canonicalUtf8);
+
+  describe(createChecksumStream.name + " webstreams API", () => {
+    if (typeof ReadableStream !== "function") {
+      // test not applicable to Node.js 16.
+      return;
+    }
+
+    const makeStream = () => {
+      return new ReadableStream({
+        start(controller) {
+          canonicalData.forEach((byte) => {
+            controller.enqueue(new Uint8Array([byte]));
+          });
+          controller.close();
+        },
+      });
+    };
+
+    it("should extend a ReadableStream", async () => {
+      const stream = makeStream();
+      const checksumStream = createChecksumStream({
+        expectedChecksum: canonicalBase64,
+        checksum: new Appender(),
+        checksumSourceLocation: "my-header",
+        source: stream,
+      });
+
+      expect(checksumStream).toBeInstanceOf(ReadableStream);
+      expect(checksumStream).toBeInstanceOf(ChecksumStreamWeb);
+
+      const collected = toUtf8(await headStream(checksumStream, Infinity));
+      expect(collected).toEqual(canonicalUtf8);
+      expect(stream.locked).toEqual(true);
+
+      // expectation is that it is resolved.
+      expect(await checksumStream.getReader().closed);
+    });
+
+    it("should throw during stream read if the checksum does not match", async () => {
+      const stream = makeStream();
+      const checksumStream = createChecksumStream({
+        expectedChecksum: "different-expected-checksum",
+        checksum: new Appender(),
+        checksumSourceLocation: "my-header",
+        source: stream,
+      });
+
+      try {
+        toUtf8(await headStream(checksumStream, Infinity));
+        throw new Error("stream was read successfully");
+      } catch (e: unknown) {
+        expect(String(e)).toEqual(
+          `Error: Checksum mismatch: expected "different-expected-checksum" but` +
+            ` received "${canonicalBase64}"` +
+            ` in response header "my-header".`
+        );
+      }
+    });
+  });
+});