corrected the release name

* See CHANGELOG for v3.0.0

* removed get-stream

* enabled linter just for test.js & from.js

* Any blob part is acceptable (jsdoc)
since the default fallback is to cast unknown items into strings

* async stat version

* import from fs/promise instead

* Updated the Readme and code examples

* known differences, buffer.Blob support, private stream, more test

* require node 14

* use fetch v3

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macOS-latest]
-        node: ["14", "12", engines]
+        node: ["16", "15", "14", engines]
         exclude:
           # On Windows, run tests with only the LTS environments.
           - os: windows-latest

.gitignore

@@ -63,3 +63,4 @@ typings/
 .env
 
 index.d.ts
+from.d.ts

CHANGELOG.md

@@ -1,6 +1,35 @@
 Changelog
 =========
 
+## v3.0.0-rc.0
+- Changed WeakMap for private field (require node 12)
+- Switch to ESM
+- blob.stream() return a subset of whatwg stream which is the async iterable
+  (it no longer return a node stream)
+- Reduced the dependency of Buffer by changing to global TextEncoder/Decoder (require node 11)
+- Disabled xo since it could understand private fields (#)
+- No longer transform the type to lowercase (https://github.com/w3c/FileAPI/issues/43)
+  This is more loose than strict, keys should be lowercased, but values should not.
+  It would require a more proper mime type parser - so we just made it loose.
+- index.js can now be imported by browser & deno since it no longer depends on any
+  core node features (but why would you? other environment can benefit from it)
+
+## v2.1.2
+- Fixed a bug where `start` in BlobDataItem was undefined (#85)
+
+## v2.1.1
+- Add nullish values checking in Symbol.hasInstance (#82)
+- Add generated typings for from.js file (#80)
+- Updated dev dependencies
+
+## v2.1.0
+- Fix: .slice has an implementation bug (#54).
+- Added blob backed up by filesystem (#55)
+
+## v2.0.1
+
+- Fix: remove upper bound for node engine semver (#49).
+
 ## v2.0.0
 
 > Note: This release was previously published as `1.0.7`, but as it contains breaking changes, we renamed it to `2.0.0`.

README.md

@@ -13,18 +13,116 @@ A Blob implementation in Node.js, originally from [node-fetch](https://github.co
 npm install fetch-blob
 ```
 
+<details>
+  <summary>Upgrading from 2x to 3x</summary>
+
+  Updating from 2 to 3 should be a breeze since there is not many changes to the blob specification.
+  The major cause of a major release is coding standards.
+    - internal WeakMaps was replaced with private fields
+    - internal Buffer.from was replaced with TextEncoder/Decoder
+    - internal buffers was replaced with Uint8Arrays
+    - CommonJS was replaced with ESM
+    - The node stream returned by calling `blob.stream()` was replaced with a simple generator function that yields Uint8Array (Breaking change)
+      (Read "Differences from other blobs" for more info.)
+
+    All of this changes have made it dependency free of any core node modules, so it would be possible to just import it using http-import from a CDN without any bundling
+
+</details>
+
+<details>
+  <summary>Differences from other Blobs</summary>
+
+  - Unlike NodeJS `buffer.Blob` (Added in: v15.7.0) and browser native Blob this polyfilled version can't be sent via PostMessage
+  - This blob version is more arbitrary, it can be constructed with blob parts that isn't a instance of itself
+  it has to look and behave as a blob to be accepted as a blob part.
+    - The benefit of this is that you can create other types of blobs that don't contain any internal data that has to be read in other ways, such as the `BlobDataItem` created in `from.js` that wraps a file path into a blob-like item and read lazily (nodejs plans to [implement this][fs-blobs] as well)
+  - The `blob.stream()` is the most noticeable differences. It returns a AsyncGeneratorFunction that yields Uint8Arrays
+
+  The reasoning behind `Blob.prototype.stream()` is that NodeJS readable stream
+  isn't spec compatible with whatwg streams and we didn't want to import the hole whatwg stream polyfill for node
+  or browserify NodeJS streams for the browsers and picking any flavor over the other. So we decided to opted out
+  of any stream and just implement the bear minium of what both streams have in common which is the asyncIterator
+  that both yields Uint8Array. this is the most isomorphic way with the use of `for-await-of` loops.
+  It would be redundant to convert anything to whatwg streams and than convert it back to
+  node streams since you work inside of Node.
+  It will probably stay like this until nodejs get native support for whatwg<sup>[1][https://github.com/nodejs/whatwg-stream]</sup> streams and whatwg stream add the node
+  equivalent for `Readable.from(iterable)`<sup>[2](https://github.com/whatwg/streams/issues/1018)</sup>
+
+  But for now if you really need a Node Stream then you can do so using this transformation
+  ```js
+    import {Readable} from 'stream'
+    const stream = Readable.from(blob.stream())
+  ```
+  But if you don't need it to be a stream then you can just use the asyncIterator part of it that is isomorphic.
+  ```js
+    for await (const chunk of blob.stream()) {
+      console.log(chunk) // uInt8Array
+    }
+  ```
+  If you need to make some feature detection to fix this different behavior
+  ```js
+  if (Blob.prototype.stream?.constructor?.name === 'AsyncGeneratorFunction') {
+    // not spec compatible, monkey patch it...
+    // (Alternative you could extend the Blob and use super.stream())
+    let orig = Blob.prototype.stream
+    Blob.prototype.stream = function () {
+      const iterator = orig.call(this)
+      return new ReadableStream({
+        async pull (ctrl) {
+          const next = await iterator.next()
+          return next.done ? ctrl.close() : ctrl.enqueue(next.value)
+        }
+      })
+    }
+  }
+  ```
+  Possible feature whatwg version: `ReadableStream.from(iterator)`
+  It's also possible to delete this method and instead use `.slice()` and `.arrayBuffer()` since it has both a public and private stream method
+</details>
+
 ## Usage
 
 ```js
-const Blob = require('fetch-blob');
-const fetch = require('node-fetch');
+// Ways to import
+// (PS it's dependency free ESM package so regular http-import from CDN works too)
+import Blob from 'fetch-blob'
+import {Blob} from 'fetch-blob'
+const {Blob} = await import('fetch-blob')
 
-fetch('https://httpbin.org/post', {
-    method: 'POST',
-    body: new Blob(['Hello World'], { type: 'text/plain' })
-})
-    .then(res => res.json());
-    .then(json => console.log(json));
+
+// Ways to read the blob:
+const blob = new Blob(['hello, world'])
+
+await blob.text()
+await blob.arrayBuffer()
+for await (let chunk of  blob.stream()) { ... }
+
+// turn the async iterator into a node stream
+stream.Readable.from(blob.stream())
+
+// turn the async iterator into a whatwg stream (feature)
+globalThis.ReadableStream.from(blob.stream())
+```
+
+### Blob part backed up by filesystem
+To use, install [domexception](https://github.com/jsdom/domexception).
+
+```sh
+npm install fetch-blob domexception
+```
+
+```js
+// The default export is sync and use fs.stat to retrieve size & last modified
+import blobFromSync from 'fetch-blob/from.js'
+import {Blob, blobFrom, blobFromSync} from 'fetch-blob/from.js'
+
+const fsBlob1 = blobFromSync('./2-GiB-file.bin')
+const fsBlob2 = await blobFrom('./2-GiB-file.bin')
+
+// Not a 4 GiB memory snapshot, just holds 3 references
+// points to where data is located on the disk
+const blob = new Blob([fsBlob1, fsBlob2, 'memory'])
+console.log(blob.size) // 4 GiB
 ```
 
 See the [MDN documentation](https://developer.mozilla.org/en-US/docs/Web/API/Blob) and [tests](https://github.com/node-fetch/fetch-blob/blob/master/test.js) for more details.
@@ -37,3 +135,4 @@ See the [MDN documentation](https://developer.mozilla.org/en-US/docs/Web/API/Blo
 [codecov-url]: https://codecov.io/gh/node-fetch/fetch-blob
 [install-size-image]: https://flat.badgen.net/packagephobia/install/fetch-blob
 [install-size-url]: https://packagephobia.now.sh/result?p=fetch-blob
+[fs-blobs]: https://github.com/nodejs/node/issues/37340

from.js

@@ -0,0 +1,75 @@
+import {statSync, createReadStream} from 'fs';
+import {stat} from 'fs/promises';
+import DOMException from 'domexception';
+import Blob from './index.js';
+
+/**
+ * @param {string} path filepath on the disk
+ * @returns {Blob}
+ */
+ const blobFromSync = path => from(statSync(path), path);
+
+/**
+ * @param {string} path filepath on the disk
+ * @returns {Promise<Blob>}
+ */
+ const blobFrom = path => stat(path).then(stat => from(stat, path));
+
+const from = (stat, path) => new Blob([new BlobDataItem({
+	path,
+	size: stat.size,
+	lastModified: stat.mtimeMs,
+	start: 0
+})]);
+
+/**
+ * This is a blob backed up by a file on the disk
+ * with minium requirement. Its wrapped around a Blob as a blobPart
+ * so you have no direct access to this.
+ *
+ * @private
+ */
+class BlobDataItem {
+	#path;
+	#start;
+
+	constructor(options) {
+		this.#path = options.path;
+		this.#start = options.start;
+		this.size = options.size;
+		this.lastModified = options.lastModified
+	}
+
+	/**
+	 * Slicing arguments is first validated and formatted
+	 * to not be out of range by Blob.prototype.slice
+	 */
+	slice(start, end) {
+		return new BlobDataItem({
+			path: this.#path,
+			lastModified: this.lastModified,
+			size: end - start,
+			start
+		});
+	}
+
+	async * stream() {
+		const {mtimeMs} = await stat(this.#path)
+		if (mtimeMs > this.lastModified) {
+			throw new DOMException('The requested file could not be read, typically due to permission problems that have occurred after a reference to a file was acquired.', 'NotReadableError');
+		}
+		if (this.size) {
+			yield * createReadStream(this.#path, {
+				start: this.#start,
+				end: this.#start + this.size - 1
+			});
+		}
+	}
+
+	get [Symbol.toStringTag]() {
+		return 'Blob';
+	}
+}
+
+export default blobFromSync;
+export {Blob, blobFrom, blobFromSync};

index.js

@@ -1,71 +1,76 @@
-const {Readable} = require('stream');
+// 64 KiB (same size chrome slice theirs blob into Uint8array's)
+const POOL_SIZE = 65536;
 
-/**
- * @type {WeakMap<Blob, {type: string, size: number, parts: (Blob | Buffer)[] }>}
- */
-const wm = new WeakMap();
-
-async function * read(parts) {
-	for (const part of parts) {
+/** @param {(Blob | Uint8Array)[]} parts */
+async function * toIterator (parts, clone = true) {
+	for (let part of parts) {
 		if ('stream' in part) {
 			yield * part.stream();
+		} else if (ArrayBuffer.isView(part)) {
+			if (clone) {
+				let position = part.byteOffset;
+				let end = part.byteOffset + part.byteLength;
+				while (position !== end) {
+					const size = Math.min(end - position, POOL_SIZE);
+					const chunk = part.buffer.slice(position, position + size);
+					yield new Uint8Array(chunk);
+					position += chunk.byteLength;
+				}
+			} else {
+				yield part;
+			}
 		} else {
-			yield part;
+			// For blobs that have arrayBuffer but no stream method (nodes buffer.Blob)
+			let position = 0;
+			while (position !== part.size) {
+				const chunk = part.slice(position, Math.min(part.size, position + POOL_SIZE));
+				const buffer = await chunk.arrayBuffer();
+				position += buffer.byteLength;
+				yield new Uint8Array(buffer);
+			}
 		}
 	}
 }
 
-/**
- * @template T
- * @param {T} object
- * @returns {T is Blob}
- */
-const isBlob = object => {
-	return (
-		typeof object === 'object' &&
-		typeof object.stream === 'function' &&
-		typeof object.constructor === 'function' &&
-		/^(Blob|File)$/.test(object[Symbol.toStringTag])
-	);
-};
+export default class Blob {
+
+	/** @type {Array.<(Blob|Uint8Array)>} */
+	#parts = [];
+	#type = '';
+	#size = 0;
 
-class Blob {
 	/**
 	 * The Blob() constructor returns a new Blob object. The content
 	 * of the blob consists of the concatenation of the values given
 	 * in the parameter array.
 	 *
-	 * @param {(ArrayBufferLike | ArrayBufferView | Blob | Buffer | string)[]} blobParts
+	 * @param {*} blobParts
 	 * @param {{ type?: string }} [options]
 	 */
-	constructor(blobParts = [], options = {type: ''}) {
+	constructor(blobParts = [], options = {}) {
 		let size = 0;
 
 		const parts = blobParts.map(element => {
-			let buffer;
-			if (Buffer.isBuffer(element)) {
-				buffer = element;
-			} else if (ArrayBuffer.isView(element)) {
-				buffer = Buffer.from(element.buffer, element.byteOffset, element.byteLength);
+			let part;
+			if (ArrayBuffer.isView(element)) {
+				part = new Uint8Array(element.buffer.slice(element.byteOffset, element.byteOffset + element.byteLength));
 			} else if (element instanceof ArrayBuffer) {
-				buffer = Buffer.from(element);
-			} else if (isBlob(element)) {
-				buffer = element;
+				part = new Uint8Array(element.slice(0));
+			} else if (element instanceof Blob) {
+				part = element;
 			} else {
-				buffer = Buffer.from(typeof element === 'string' ? element : String(element));
+				part = new TextEncoder().encode(String(element));
 			}
 
-			size += buffer.length || buffer.size || 0;
-			return buffer;
+			size += ArrayBuffer.isView(part) ? part.byteLength : part.size;
+			return part;
 		});
 
-		const type = options.type === undefined ? '' : String(options.type).toLowerCase();
+		const type = options.type === undefined ? '' : String(options.type);
 
-		wm.set(this, {
-			type: /[^\u0020-\u007E]/.test(type) ? '' : type,
-			size,
-			parts
-		});
+		this.#type = /[^\u0020-\u007E]/.test(type) ? '' : type;
+		this.#size = size;
+		this.#parts = parts;
 	}
 
 	/**
@@ -73,14 +78,14 @@ class Blob {
 	 * size of the Blob in bytes.
 	 */
 	get size() {
-		return wm.get(this).size;
+		return this.#size;
 	}
 
 	/**
 	 * The type property of a Blob object returns the MIME type of the file.
 	 */
 	get type() {
-		return wm.get(this).type;
+		return this.#type;
 	}
 
 	/**
@@ -91,7 +96,16 @@ class Blob {
 	 * @return {Promise<string>}
 	 */
 	async text() {
-		return Buffer.from(await this.arrayBuffer()).toString();
+		// More optimized than using this.arrayBuffer()
+		// that requires twice as much ram
+		const decoder = new TextDecoder();
+		let str = '';
+		for await (let part of toIterator(this.#parts, false)) {
+			str += decoder.decode(part, { stream: true });
+		}
+		// Remaining
+		str += decoder.decode();
+		return str;
 	}
 
 	/**
@@ -104,7 +118,7 @@ class Blob {
 	async arrayBuffer() {
 		const data = new Uint8Array(this.size);
 		let offset = 0;
-		for await (const chunk of this.stream()) {
+		for await (const chunk of toIterator(this.#parts, false)) {
 			data.set(chunk, offset);
 			offset += chunk.length;
 		}
@@ -113,13 +127,13 @@ class Blob {
 	}
 
 	/**
-	 * The Blob interface's stream() method is difference from native
-	 * and uses node streams instead of whatwg streams.
+	 * The Blob stream() implements partial support of the whatwg stream
+	 * by only being async iterable.
 	 *
-	 * @returns {Readable} Node readable stream
+	 * @returns {AsyncGenerator<Uint8Array>}
 	 */
-	stream() {
-		return Readable.from(read(wm.get(this).parts));
+	async * stream() {
+		yield * toIterator(this.#parts, true);
 	}
 
 	/**
@@ -138,7 +152,7 @@ class Blob {
 		let relativeEnd = end < 0 ? Math.max(size + end, 0) : Math.min(end, size);
 
 		const span = Math.max(relativeEnd - relativeStart, 0);
-		const parts = wm.get(this).parts.values();
+		const parts = this.#parts;
 		const blobParts = [];
 		let added = 0;
 
@@ -150,9 +164,15 @@ class Blob {
 				relativeStart -= size;
 				relativeEnd -= size;
 			} else {
-				const chunk = part.slice(relativeStart, Math.min(size, relativeEnd));
+				let chunk
+				if (ArrayBuffer.isView(part)) {
+					chunk = part.subarray(relativeStart, Math.min(size, relativeEnd));
+					added += chunk.byteLength
+				} else {
+					chunk = part.slice(relativeStart, Math.min(size, relativeEnd));
+					added += chunk.size
+				}
 				blobParts.push(chunk);
-				added += size;
 				relativeStart = 0; // All next sequental parts should start at 0
 
 				// don't add the overflow to new blobParts
@@ -162,11 +182,29 @@ class Blob {
 			}
 		}
 
-		const blob = new Blob([], {type});
-		Object.assign(wm.get(blob), {size: span, parts: blobParts});
+		const blob = new Blob([], {type: String(type).toLowerCase()});
+		blob.#size = span;
+		blob.#parts = blobParts;
 
 		return blob;
 	}
+
+	get [Symbol.toStringTag]() {
+		return 'Blob';
+	}
+
+	static [Symbol.hasInstance](object) {
+		return (
+			object &&
+			typeof object === 'object' &&
+			typeof object.constructor === 'function' &&
+			(
+				typeof object.stream === 'function' ||
+				typeof object.arrayBuffer === 'function'
+			) &&
+			/^(Blob|File)$/.test(object[Symbol.toStringTag])
+		);
+	}
 }
 
 Object.defineProperties(Blob.prototype, {
@@ -175,11 +213,4 @@ Object.defineProperties(Blob.prototype, {
 	slice: {enumerable: true}
 });
 
-Object.defineProperty(Blob.prototype, Symbol.toStringTag, {
-	value: 'Blob',
-	writable: false,
-	enumerable: false,
-	configurable: true
-});
-
-module.exports = Blob;
+export { Blob };

package.json

@@ -1,18 +1,21 @@
 {
     "name": "fetch-blob",
-    "version": "2.0.0",
+    "version": "3.0.0-rc.0",
     "description": "A Blob implementation in Node.js, originally from node-fetch.",
     "main": "index.js",
+    "type": "module",
     "files": [
+        "from.js",
         "index.js",
-        "index.d.ts"
+        "index.d.ts",
+        "from.d.ts"
     ],
     "scripts": {
-        "lint": "xo",
-        "test": "xo && ava",
+        "lint": "xo test.js",
+        "test": "npm run lint && ava",
         "report": "c8 --reporter json --reporter text ava",
         "coverage": "c8 --reporter json --reporter text ava && codecov -f coverage/coverage-final.json",
-        "prepublishOnly": "tsc --declaration --emitDeclarationOnly --allowJs index.js"
+        "prepublishOnly": "tsc --declaration --emitDeclarationOnly --allowJs index.js from.js"
     },
     "repository": "https://github.com/node-fetch/fetch-blob.git",
     "keywords": [
@@ -20,7 +23,7 @@
         "node-fetch"
     ],
     "engines": {
-        "node": "^10.17.0"
+        "node": ">=14.0.0"
     },
     "author": "David Frank",
     "license": "MIT",
@@ -28,16 +31,17 @@
         "url": "https://github.com/node-fetch/fetch-blob/issues"
     },
     "homepage": "https://github.com/node-fetch/fetch-blob#readme",
-    "devDependencies": {
-        "ava": "^3.8.2",
-        "c8": "^7.2.0",
-        "codecov": "^3.7.0",
-        "get-stream": "^5.1.0",
-        "node-fetch": "^2.6.0",
-        "typescript": "^3.9.5",
-        "xo": "^0.32.0"
-    },
     "xo": {
+        "rules": {
+            "unicorn/import-index": "off",
+            "import/extensions": [
+                "error",
+                "always",
+                {
+                    "ignorePackages": true
+                }
+            ]
+        },
         "overrides": [
             {
                 "files": "test.js",
@@ -48,5 +52,18 @@
             }
         ]
     },
-    "dependencies": {}
+    "peerDependenciesMeta": {
+        "domexception": {
+            "optional": true
+        }
+    },
+    "devDependencies": {
+        "ava": "^3.15.0",
+        "c8": "^7.7.1",
+        "codecov": "^3.8.1",
+        "domexception": "^2.0.1",
+        "node-fetch": "^3.0.0-beta.9",
+        "typescript": "^4.2.4",
+        "xo": "^0.38.2"
+    }
 }

test.js

@@ -1,8 +1,12 @@
-const test = require('ava');
-const Blob = require('.');
-const getStream = require('get-stream');
-const {Response} = require('node-fetch');
-const {TextDecoder} = require('util');
+import fs from 'fs';
+import test from 'ava';
+import {Response} from 'node-fetch';
+import {Readable} from 'stream';
+import buffer from 'buffer';
+import Blob from './index.js';
+import syncBlob, {blobFromSync, blobFrom} from './from.js';
+
+const license = fs.readFileSync('./LICENSE', 'utf-8');
 
 test('new Blob()', t => {
 	const blob = new Blob(); // eslint-disable-line no-unused-vars
@@ -23,11 +27,12 @@ test('Blob ctor parts', async t => {
 		new Uint8Array([101]).buffer,
 		Buffer.from('f'),
 		new Blob(['g']),
-		{}
+		{},
+		new URLSearchParams('foo')
 	];
 
 	const blob = new Blob(parts);
-	t.is(await blob.text(), 'abcdefg[object Object]');
+	t.is(await blob.text(), 'abcdefg[object Object]foo=');
 });
 
 test('Blob size', t => {
@@ -79,8 +84,10 @@ test('Blob stream()', async t => {
 	const data = 'a=1';
 	const type = 'text/plain';
 	const blob = new Blob([data], {type});
-	const result = await getStream(blob.stream());
-	t.is(result, data);
+
+	for await (const chunk of blob.stream()) {
+		t.is(chunk.join(), [97, 61, 49].join());
+	}
 });
 
 test('Blob toString()', t => {
@@ -114,6 +121,12 @@ test('Blob slice(0, -1)', async t => {
 	t.is(await blob.text(), 'abcdefg');
 });
 
+test('Blob(["hello ", "world"]).slice(5)', async t => {
+	const parts = ['hello ', 'world'];
+	const blob = new Blob(parts);
+	t.is(await blob.slice(5).text(), ' world');
+});
+
 test('throw away unwanted parts', async t => {
 	const blob = new Blob(['a', 'b', 'c']).slice(1, 2);
 	t.is(await blob.text(), 'b');
@@ -123,7 +136,7 @@ test('Blob works with node-fetch Response.blob()', async t => {
 	const data = 'a=1';
 	const type = 'text/plain';
 	const blob = new Blob([data], {type});
-	const response = new Response(blob);
+	const response = new Response(Readable.from(blob.stream()));
 	const blob2 = await response.blob();
 	t.is(await blob2.text(), data);
 });
@@ -132,7 +145,112 @@ test('Blob works with node-fetch Response.text()', async t => {
 	const data = 'a=1';
 	const type = 'text/plain';
 	const blob = new Blob([data], {type});
-	const response = new Response(blob);
+	const response = new Response(Readable.from(blob.stream()));
 	const text = await response.text();
 	t.is(text, data);
 });
+
+test('blob part backed up by filesystem', async t => {
+	const blob = blobFromSync('./LICENSE');
+	t.is(await blob.slice(0, 3).text(), license.slice(0, 3));
+	t.is(await blob.slice(4, 11).text(), license.slice(4, 11));
+});
+
+test('Reading after modified should fail', async t => {
+	const blob = blobFromSync('./LICENSE');
+	await new Promise(resolve => {
+		setTimeout(resolve, 100);
+	});
+	const now = new Date();
+	// Change modified time
+	fs.utimesSync('./LICENSE', now, now);
+	const error = await blob.text().catch(error => error);
+	t.is(error instanceof Error, true);
+	t.is(error.name, 'NotReadableError');
+});
+
+test('Reading from the stream created by blobFrom', async t => {
+	const blob = blobFromSync('./LICENSE');
+	const actual = await blob.text();
+	t.is(actual, license);
+});
+
+test('create a blob from path asynchronous', async t => {
+	const blob = await blobFrom('./LICENSE');
+	const actual = await blob.text();
+	t.is(actual, license);
+});
+
+test('Reading empty blobs', async t => {
+	const blob = blobFromSync('./LICENSE').slice(0, 0);
+	const actual = await blob.text();
+	t.is(actual, '');
+});
+
+test('Blob-ish class is an instance of Blob', t => {
+	class File {
+		stream() {}
+
+		get [Symbol.toStringTag]() {
+			return 'File';
+		}
+	}
+
+	t.true(new File() instanceof Blob);
+});
+
+test('Instanceof check returns false for nullish values', t => {
+	t.false(null instanceof Blob);
+});
+
+/** @see https://github.com/w3c/FileAPI/issues/43 - important to keep boundary value */
+test('Dose not lowercase the blob values', t => {
+	const type = 'multipart/form-data; boundary=----WebKitFormBoundaryTKqdrVt01qOBltBd';
+	t.is(new Blob([], {type}).type, type);
+});
+
+test('Parts are immutable', async t => {
+	const buf = new Uint8Array([97]);
+	const blob = new Blob([buf]);
+	buf[0] = 98;
+	t.is(await blob.text(), 'a');
+});
+
+test('Blobs are immutable', async t => {
+	const buf = new Uint8Array([97]);
+	const blob = new Blob([buf]);
+	const chunk = await blob.stream().next();
+	t.is(chunk.value[0], 97);
+	chunk.value[0] = 98;
+	t.is(await blob.text(), 'a');
+});
+
+// This was necessary to avoid large ArrayBuffer clones (slice)
+test('Large chunks are divided into smaller chunks', async t => {
+	const buf = new Uint8Array(65590);
+	const blob = new Blob([buf]);
+	let i = 0;
+	// eslint-disable-next-line no-unused-vars
+	for await (const chunk of blob.stream()) {
+		i++;
+	}
+
+	t.is(i === 2, true);
+});
+
+test('Can use named import - as well as default', async t => {
+	const {Blob, default: def} = await import('./index.js');
+	t.is(Blob, def);
+});
+
+test('default from.js exports blobFromSync', t => {
+	t.is(blobFromSync, syncBlob);
+});
+
+if (buffer.Blob) {
+	test('Can wrap buffer.Blob to a fetch-blob', async t => {
+		const blob1 = new buffer.Blob(['blob part']);
+		const blob2 = new Blob([blob1]);
+		t.is(await blob2.text(), 'blob part');
+	});
+}