Mocking uploading files with Needle does not work

[sindilevich]

I am getting Uncaught Error: ENOENT: no such file or directory, open 'C:\Temp\mockFs\fake\base\path\file.png' when trying to mock out uploading files with needle.

System: Windows 7 x64
node.js: 10.8.0
npm: 6.3.0

needle takes file paths and uploads them onto server via HTTP POST. I am setting a file-system mock before using needle.

The file that uses needle:

// poster.ts
import needle from "needle";

export class Poster {
	public async post(file, textFile) {
		const payload = {
			values: {
				Attachment1: file,
				Attachment2: textFile
			}
		};

		return needle("post", "http://localhost:8080/api/files",
			{
				"attach-Attachment1": { file: file, content_type: "image/png" },
				"attach-Attachment2": { file: textFile, content_type: "application/json" },
				"entry": { value: JSON.stringify(payload), content_type: "application/json" }
			},
			{ multipart: true });
	}
}

And here is the test suite:

// poster-test.ts
import { expect, use } from "chai";
import chaiAsPromised from "chai-as-promised";
import mockFs from "mock-fs";
import nock from "nock";
import { Poster } from "./poster";

const poster = new Poster();

describe("Poster can...", () => {
	beforeEach("Setup Node.http.request stub and mockFs", () => {
		use(chaiAsPromised);
		mockFs({
			fake: {
				base: {
					path: {
						"file.png": "",
						"file.txt": "This is a textual file"
					}
				}
			}
		});
	});

	afterEach("Restore after mockFs", () => {
		mockFs.restore();
	});

	it("Succedes to post", async () => {
		nock("http://localhost:8080")
			.post(/^\/api.+/gi)
			.reply(200, (requestBody: string) => console.info(requestBody));
		await poster.post("fake/base/path/file.png", "fake/base/path/file.txt");
	});
});

The test is run with mocha, with extensions by chai.