fix(util-body-length-node): calculateBodyLength for Readable stream with range

packages/util-body-length-node/src/index.spec.ts

@@ -1,3 +1,8 @@
+import { promises } from 'fs';
+import { createReadStream, writeFile } from "fs-extra";
+import * as os from "os";
+import * as path from "path";
+
 import { calculateBodyLength } from "./";
 
 const arrayBuffer = new ArrayBuffer(1);
@@ -28,4 +33,28 @@ describe("caclulateBodyLength", () => {
   it("should handle DataView inputs", () => {
     expect(calculateBodyLength(view)).toEqual(1);
   });
+
+  it("should handle a Readable from a file", async () => {
+    const tmpDir = await promises.mkdtemp(path.join(os.tmpdir(), 'test1-'));
+    const filePath = path.join(tmpDir, "foo");
+    await writeFile(filePath, "foo");
+    const handle = await promises.open(filePath, 'r');
+    const readStream = createReadStream(filePath, {fd: handle.fd});
+    expect(calculateBodyLength(readStream)).toEqual(3);
+    readStream.destroy();
+    await promises.unlink(filePath);
+    await promises.rmdir(tmpDir);
+  });
+
+  it("should handle Readable with start end from a file", async () => {
+    const tmpDir = await promises.mkdtemp(path.join(os.tmpdir(), 'test2-'));
+    const filePath = path.join(tmpDir, "foo");
+    await writeFile(filePath, "foo");
+    const handle = await promises.open(filePath, 'r');
+    const readStream = createReadStream(filePath, {fd: handle.fd, start: 1, end: 1});
+    expect(calculateBodyLength(readStream)).toEqual(1);
+    readStream.destroy();
+    await promises.unlink(filePath);
+    await promises.rmdir(tmpDir);
+  });
 });

packages/util-body-length-node/src/index.ts

@@ -11,6 +11,8 @@ export function calculateBodyLength(body: any): number | undefined {
     return body.byteLength;
   } else if (typeof body.size === "number") {
     return body.size;
+  } else if (typeof body.start === "number" && typeof body.end === "number") {
+    return body.end + 1 - body.start;
   } else if (typeof body.path === "string") {
     // handles fs readable streams
     return lstatSync(body.path).size;