Add tests for ReadableStream.from()

test/unit/readable-stream/from.spec.js

@@ -0,0 +1,39 @@
+const { ReadableStream } = require('../../../');
+const { ReadableStream: NodeReadableStream } = require('node:stream/web');
+
+describe('ReadableStream.from()', () => {
+  it('supports a Node.js ReadableStream', async () => {
+    const native = new NodeReadableStream({
+      start(c) {
+        c.enqueue('a');
+        c.enqueue('b');
+        c.close();
+      }
+    });
+    const wrapped = ReadableStream.from(native);
+    expect(wrapped instanceof ReadableStream).toBe(true);
+    const reader = wrapped.getReader();
+    await expectAsync(reader.read()).toBeResolvedTo({ done: false, value: 'a' });
+    await expectAsync(reader.read()).toBeResolvedTo({ done: false, value: 'b' });
+    await expectAsync(reader.read()).toBeResolvedTo({ done: true, value: undefined });
+  });
+
+  it('supports a ReadableStream-like object', async () => {
+    let i = 0;
+    const closedPromise = new Promise(() => {});
+    const readerLike = {
+      get closed() { return closedPromise; },
+      async read() { return { done: false, value: ++i }; },
+      async cancel() {},
+      releaseLock() {}
+    };
+    const streamLike = {
+      getReader() { return readerLike; }
+    };
+    const wrapped = ReadableStream.from(streamLike);
+    expect(wrapped instanceof ReadableStream).toBe(true);
+    const reader = wrapped.getReader();
+    await expectAsync(reader.read()).toBeResolvedTo({ done: false, value: 1 });
+    await expectAsync(reader.read()).toBeResolvedTo({ done: false, value: 2 });
+  });
+});