Implemented non-RDF fetch

CHANGELOG.md

@@ -13,3 +13,4 @@ First release! What's possible with this first release:
 - Read data from datasets.
 - Manipulate data in datasets.
 - Inspect a user's permissions w.r.t. a given Resource. (Experimental.)
+- Retrieve any file (including non-RDF) from a Pod.

src/index.test.ts

@@ -1,4 +1,5 @@
 import {
+  fetchFile,
   fetchLitDataset,
   saveLitDatasetAt,
   saveLitDatasetInContainer,
@@ -66,6 +67,7 @@ import {
 // These tests aren't too useful in preventing bugs, but they work around this issue:
 // https://github.com/facebook/jest/issues/10032
 it("exports the public API from the entry file", () => {
+  expect(fetchFile).toBeDefined();
   expect(fetchLitDataset).toBeDefined();
   expect(saveLitDatasetAt).toBeDefined();
   expect(saveLitDatasetInContainer).toBeDefined();

src/index.ts

@@ -1,5 +1,6 @@
 import { DatasetCore, Quad, NamedNode, BlankNode } from "rdf-js";
 
+export { fetchFile } from "./nonRdfData";
 export {
   fetchLitDataset,
   saveLitDatasetAt,

src/nonRdfData.test.ts

@@ -0,0 +1,105 @@
+import { describe, it, expect } from "@jest/globals";
+
+jest.mock("./fetcher", () => ({
+  fetch: jest
+    .fn()
+    .mockImplementation(() =>
+      Promise.resolve(
+        new Response("Some data", { status: 200, statusText: "OK" })
+      )
+    ),
+}));
+
+import { fetchFile } from "./nonRdfData";
+import { Headers, Response } from "cross-fetch";
+
+describe("Non-RDF data fetch", () => {
+  it("should GET a remote resource using cross-fetch if no other fetcher is available", async () => {
+    const fetcher = jest.requireMock("./fetcher") as {
+      fetch: jest.Mock<
+        ReturnType<typeof window.fetch>,
+        [RequestInfo, RequestInit?]
+      >;
+    };
+
+    fetcher.fetch.mockReturnValue(
+      Promise.resolve(
+        new Response("Some data", { status: 200, statusText: "OK" })
+      )
+    );
+
+    const response = await fetchFile("https://some.url");
+
+    expect(fetcher.fetch.mock.calls).toEqual([["https://some.url", undefined]]);
+    expect(response).toEqual(
+      new Response("Some data", { status: 200, statusText: "OK" })
+    );
+  });
+
+  it("should GET a remote resource using the provided fetcher", async () => {
+    const mockFetch = jest
+      .fn(window.fetch)
+      .mockReturnValue(
+        Promise.resolve(
+          new Response("Some data", { status: 200, statusText: "OK" })
+        )
+      );
+
+    const response = await fetchFile("https://some.url", {
+      fetch: mockFetch,
+    });
+
+    expect(mockFetch.mock.calls).toEqual([["https://some.url", undefined]]);
+    expect(response).toEqual(
+      new Response("Some data", { status: 200, statusText: "OK" })
+    );
+  });
+
+  it("should pass the request headers through", async () => {
+    const mockFetch = jest
+      .fn(window.fetch)
+      .mockReturnValue(
+        Promise.resolve(
+          new Response("Some data", { status: 200, statusText: "OK" })
+        )
+      );
+
+    const response = await fetchFile("https://some.url", {
+      init: {
+        headers: new Headers({ Accept: "text/turtle" }),
+      },
+      fetch: mockFetch,
+    });
+
+    expect(mockFetch.mock.calls).toEqual([
+      [
+        "https://some.url",
+        {
+          headers: new Headers({ Accept: "text/turtle" }),
+        },
+      ],
+    ]);
+    expect(response).toEqual(
+      new Response("Some data", { status: 200, statusText: "OK" })
+    );
+  });
+
+  it("should return the response even on failure", async () => {
+    const mockFetch = jest
+      .fn(window.fetch)
+      .mockReturnValue(
+        Promise.resolve(
+          new Response(undefined, { status: 400, statusText: "Bad request" })
+        )
+      );
+
+    const response = await fetchFile("https://some.url", {
+      fetch: mockFetch,
+    });
+
+    expect(mockFetch.mock.calls).toEqual([["https://some.url", undefined]]);
+    expect(response).toEqual(
+      new Response(undefined, { status: 400, statusText: "Bad request" })
+    );
+  });
+});

src/nonRdfData.ts

@@ -0,0 +1,27 @@
+import { fetch } from "./fetcher";
+
+interface GetFileOptions {
+  fetch: typeof window.fetch;
+  init: RequestInit;
+}
+
+const defaultGetFileOptions = {
+  fetch: fetch,
+};
+
+/**
+ * getFile fetches a file, and returns it as a blob of data.
+ *
+ * @param url The IRI of the fetched file
+ * @param options Fetching options: a custom fetcher and/or headers.
+ */
+export async function fetchFile(
+  input: RequestInfo,
+  options: Partial<GetFileOptions> = defaultGetFileOptions
+): Promise<Response> {
+  const config = {
+    ...defaultGetFileOptions,
+    ...options,
+  };
+  return config.fetch(input, config.init);
+}