From c8e9e38b03ff84e7ef0affd0613f7960f187d529 Mon Sep 17 00:00:00 2001
From: Kir_Antipov <kp.antipov@gmail.com>
Date: Fri, 10 Feb 2023 10:10:10 +0000
Subject: [PATCH] Made utility methods to work with `Blob`

---
 src/utils/net/blob.ts             | 46 +++++++++++++++++++++++++++
 tests/unit/utils/net/blob.spec.ts | 53 +++++++++++++++++++++++++++++++
 2 files changed, 99 insertions(+)
 create mode 100644 src/utils/net/blob.ts
 create mode 100644 tests/unit/utils/net/blob.spec.ts

diff --git a/src/utils/net/blob.ts b/src/utils/net/blob.ts
new file mode 100644
index 0000000..6fd3343
--- /dev/null
+++ b/src/utils/net/blob.ts
@@ -0,0 +1,46 @@
+import { Blob as BlobPolyfill, blobFrom, blobFromSync } from "node-fetch";
+import { ConstructorReturnType } from "@/utils/types";
+
+/**
+ * A `Blob` encapsulates immutable, raw data that can be safely shared across multiple worker threads.
+ */
+export const Blob = BlobPolyfill;
+
+/**
+ * A `Blob` encapsulates immutable, raw data that can be safely shared across multiple worker threads.
+ */
+export type Blob = ConstructorReturnType<typeof BlobPolyfill>;
+
+/**
+ * Checks if an object is a `Blob`.
+ *
+ * @param blob - The object to check.
+ *
+ * @returns `true` if the object is a `Blob`; otherwise, `false`.
+ */
+export function isBlob(blob: unknown): blob is Blob {
+    const name = blob?.[Symbol.toStringTag];
+    return name === "Blob" || name  === "File";
+}
+
+/**
+ * Reads a file from the given path and returns its content as a `Blob`.
+ *
+ * @param path - The file path to read the content from.
+ *
+ * @returns A `Promise` that resolves to a `Blob` containing the file content.
+ */
+export function readBlob(path: string): Promise<Blob> {
+    return blobFrom(path);
+}
+
+/**
+ * Synchronously reads a file from the given path and returns its content as a `Blob`.
+ *
+ * @param path - The file path to read the content from.
+ *
+ * @returns A `Blob` containing the file content.
+ */
+export function readBlobSync(path: string): Blob {
+    return blobFromSync(path);
+}
diff --git a/tests/unit/utils/net/blob.spec.ts b/tests/unit/utils/net/blob.spec.ts
new file mode 100644
index 0000000..eef278a
--- /dev/null
+++ b/tests/unit/utils/net/blob.spec.ts
@@ -0,0 +1,53 @@
+import mockFs from "mock-fs";
+import { Blob, isBlob, readBlob, readBlobSync } from "@/utils/net/blob";
+
+beforeEach(() => {
+    mockFs({
+        "test.txt": "test",
+    });
+});
+
+afterEach(() => {
+    mockFs.restore();
+});
+
+describe("isBlob", () => {
+    test("returns true for Blob instances", () => {
+        expect(isBlob(new Blob([]))).toBe(true);
+    });
+
+    test("returns false for non-Blob objects", () => {
+        expect(isBlob({})).toBe(false);
+    });
+
+    test("returns false for null and undefined", () => {
+        expect(isBlob(null)).toBe(false);
+        expect(isBlob(undefined)).toBe(false);
+    });
+});
+
+describe("readBlob", () => {
+    test("reads a file and returns its content as a Blob", async () => {
+        const blob = await readBlob("test.txt");
+
+        expect(isBlob(blob)).toBe(true);
+        expect(await blob.text()).toBe("test");
+    });
+
+    test("throws an error for non-existent file", async () => {
+        await expect(readBlob("non-existent.txt")).rejects.toThrow();
+    });
+});
+
+describe("readBlobSync", () => {
+    test("reads a file synchronously and returns its content as a Blob", async () => {
+        const blob = readBlobSync("test.txt");
+
+        expect(isBlob(blob)).toBe(true);
+        expect(await blob.text()).toBe("test");
+    });
+
+    test("throws an error for non-existent file", () => {
+        expect(() => readBlobSync("non-existent.txt")).toThrow();
+    });
+});