diff --git a/.changeset/dirty-papayas-happen.md b/.changeset/dirty-papayas-happen.md
new file mode 100644
index 00000000..68c80675
--- /dev/null
+++ b/.changeset/dirty-papayas-happen.md
@@ -0,0 +1,5 @@
+---
+"@clack/prompts": patch
+---
+
+Exposes a new `SpinnerResult` type to describe the return type of `spinner`
diff --git a/packages/core/src/utils/index.ts b/packages/core/src/utils/index.ts
index ed2be58d..6587191c 100644
--- a/packages/core/src/utils/index.ts
+++ b/packages/core/src/utils/index.ts
@@ -1,7 +1,8 @@
 import { stdin, stdout } from 'node:process';
 import type { Key } from 'node:readline';
 import * as readline from 'node:readline';
-import type { Readable } from 'node:stream';
+import type { Readable, Writable } from 'node:stream';
+import { ReadStream } from 'node:tty';
 import { cursor } from 'sisteransi';
 import { isActionKey } from './settings.js';
 
@@ -22,12 +23,19 @@ export function setRawMode(input: Readable, value: boolean) {
 	if (i.isTTY) i.setRawMode(value);
 }
 
+export interface BlockOptions {
+	input?: Readable;
+	output?: Writable;
+	overwrite?: boolean;
+	hideCursor?: boolean;
+}
+
 export function block({
 	input = stdin,
 	output = stdout,
 	overwrite = true,
 	hideCursor = true,
-} = {}) {
+}: BlockOptions = {}) {
 	const rl = readline.createInterface({
 		input,
 		output,
@@ -35,7 +43,10 @@ export function block({
 		tabSize: 1,
 	});
 	readline.emitKeypressEvents(input, rl);
-	if (input.isTTY) input.setRawMode(true);
+
+	if (input instanceof ReadStream && input.isTTY) {
+		input.setRawMode(true);
+	}
 
 	const clear = (data: Buffer, { name, sequence }: Key) => {
 		const str = String(data);
@@ -62,7 +73,9 @@ export function block({
 		if (hideCursor) output.write(cursor.show);
 
 		// Prevent Windows specific issues: https://github.com/bombshell-dev/clack/issues/176
-		if (input.isTTY && !isWindows) input.setRawMode(false);
+		if (input instanceof ReadStream && input.isTTY && !isWindows) {
+			input.setRawMode(false);
+		}
 
 		// @ts-expect-error fix for https://github.com/nodejs/node/issues/31762#issuecomment-1441223907
 		rl.terminal = false;
diff --git a/packages/prompts/package.json b/packages/prompts/package.json
index 97e525e4..553d26b4 100644
--- a/packages/prompts/package.json
+++ b/packages/prompts/package.json
@@ -46,7 +46,8 @@
   "packageManager": "pnpm@8.6.12",
   "scripts": {
     "build": "unbuild",
-    "prepack": "pnpm build"
+    "prepack": "pnpm build",
+    "test": "vitest run"
   },
   "dependencies": {
     "@clack/core": "workspace:*",
@@ -54,6 +55,7 @@
     "sisteransi": "^1.0.5"
   },
   "devDependencies": {
-    "is-unicode-supported": "^1.3.0"
+    "is-unicode-supported": "^1.3.0",
+    "vitest": "^1.6.0"
   }
 }
diff --git a/packages/prompts/src/__snapshots__/index.test.ts.snap b/packages/prompts/src/__snapshots__/index.test.ts.snap
new file mode 100644
index 00000000..9b51db39
--- /dev/null
+++ b/packages/prompts/src/__snapshots__/index.test.ts.snap
@@ -0,0 +1,105 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`spinner > message > sets message for next frame 1`] = `
+[
+  "[?25l",
+  "│
+",
+  "◒  ",
+  "",
+  "",
+  "◐  foo",
+]
+`;
+
+exports[`spinner > start > renders frames at interval 1`] = `
+[
+  "[?25l",
+  "│
+",
+  "◒  ",
+  "",
+  "",
+  "◐  ",
+  "",
+  "",
+  "◓  ",
+  "",
+  "",
+  "◑  ",
+]
+`;
+
+exports[`spinner > start > renders message 1`] = `
+[
+  "[?25l",
+  "│
+",
+  "◒  foo",
+]
+`;
+
+exports[`spinner > start > renders timer when indicator is "timer" 1`] = `
+[
+  "[?25l",
+  "│
+",
+  "◒   [0s]",
+]
+`;
+
+exports[`spinner > stop > renders cancel symbol if code = 1 1`] = `
+[
+  "[?25l",
+  "│
+",
+  "◒  ",
+  "",
+  "",
+  "■  
+",
+  "[?25h",
+]
+`;
+
+exports[`spinner > stop > renders error symbol if code > 1 1`] = `
+[
+  "[?25l",
+  "│
+",
+  "◒  ",
+  "",
+  "",
+  "▲  
+",
+  "[?25h",
+]
+`;
+
+exports[`spinner > stop > renders message 1`] = `
+[
+  "[?25l",
+  "│
+",
+  "◒  ",
+  "",
+  "",
+  "◇  foo
+",
+  "[?25h",
+]
+`;
+
+exports[`spinner > stop > renders submit symbol and stops spinner 1`] = `
+[
+  "[?25l",
+  "│
+",
+  "◒  ",
+  "",
+  "",
+  "◇  
+",
+  "[?25h",
+]
+`;
diff --git a/packages/prompts/src/index.test.ts b/packages/prompts/src/index.test.ts
new file mode 100644
index 00000000..93eb43d7
--- /dev/null
+++ b/packages/prompts/src/index.test.ts
@@ -0,0 +1,142 @@
+import { Writable } from 'node:stream';
+import { afterEach, beforeEach, describe, expect, test, vi } from 'vitest';
+import * as prompts from './index.js';
+
+// TODO (43081j): move this into a util?
+class MockWritable extends Writable {
+	public buffer: string[] = [];
+
+	_write(
+		chunk: any,
+		_encoding: BufferEncoding,
+		callback: (error?: Error | null | undefined) => void
+	): void {
+		this.buffer.push(chunk.toString());
+		callback();
+	}
+}
+
+describe('spinner', () => {
+	let output: MockWritable;
+
+	beforeEach(() => {
+		vi.useFakeTimers();
+		output = new MockWritable();
+	});
+
+	afterEach(() => {
+		vi.restoreAllMocks();
+		vi.useRealTimers();
+	});
+
+	test('returns spinner API', () => {
+		const api = prompts.spinner({ output });
+
+		expect(api.stop).toBeTypeOf('function');
+		expect(api.start).toBeTypeOf('function');
+		expect(api.message).toBeTypeOf('function');
+	});
+
+	describe('start', () => {
+		test('renders frames at interval', () => {
+			const result = prompts.spinner({ output });
+
+			result.start();
+
+			// there are 4 frames
+			for (let i = 0; i < 4; i++) {
+				vi.advanceTimersByTime(80);
+			}
+
+			expect(output.buffer).toMatchSnapshot();
+		});
+
+		test('renders message', () => {
+			const result = prompts.spinner({ output });
+
+			result.start('foo');
+
+			vi.advanceTimersByTime(80);
+
+			expect(output.buffer).toMatchSnapshot();
+		});
+
+		test('renders timer when indicator is "timer"', () => {
+			const result = prompts.spinner({ output, indicator: 'timer' });
+
+			result.start();
+
+			vi.advanceTimersByTime(80);
+
+			expect(output.buffer).toMatchSnapshot();
+		});
+	});
+
+	describe('stop', () => {
+		test('renders submit symbol and stops spinner', () => {
+			const result = prompts.spinner({ output });
+
+			result.start();
+
+			vi.advanceTimersByTime(80);
+
+			result.stop();
+
+			vi.advanceTimersByTime(80);
+
+			expect(output.buffer).toMatchSnapshot();
+		});
+
+		test('renders cancel symbol if code = 1', () => {
+			const result = prompts.spinner({ output });
+
+			result.start();
+
+			vi.advanceTimersByTime(80);
+
+			result.stop('', 1);
+
+			expect(output.buffer).toMatchSnapshot();
+		});
+
+		test('renders error symbol if code > 1', () => {
+			const result = prompts.spinner({ output });
+
+			result.start();
+
+			vi.advanceTimersByTime(80);
+
+			result.stop('', 2);
+
+			expect(output.buffer).toMatchSnapshot();
+		});
+
+		test('renders message', () => {
+			const result = prompts.spinner({ output });
+
+			result.start();
+
+			vi.advanceTimersByTime(80);
+
+			result.stop('foo');
+
+			expect(output.buffer).toMatchSnapshot();
+		});
+	});
+
+	describe('message', () => {
+		test('sets message for next frame', () => {
+			const result = prompts.spinner({ output });
+
+			result.start();
+
+			vi.advanceTimersByTime(80);
+
+			result.message('foo');
+
+			vi.advanceTimersByTime(80);
+
+			expect(output.buffer).toMatchSnapshot();
+		});
+	});
+});
diff --git a/packages/prompts/src/index.ts b/packages/prompts/src/index.ts
index 01cd736b..8e465314 100644
--- a/packages/prompts/src/index.ts
+++ b/packages/prompts/src/index.ts
@@ -1,3 +1,4 @@
+import type { Writable } from 'node:stream';
 import { stripVTControlCharacters as strip } from 'node:util';
 import {
 	ConfirmPrompt,
@@ -727,9 +728,19 @@ export const stream = {
 
 export interface SpinnerOptions {
 	indicator?: 'dots' | 'timer';
+	output?: Writable;
 }
 
-export const spinner = ({ indicator = 'dots' }: SpinnerOptions = {}) => {
+export interface SpinnerResult {
+	start(msg?: string): void;
+	stop(msg?: string, code?: number): void;
+	message(msg?: string): void;
+}
+
+export const spinner = ({
+	indicator = 'dots',
+	output = process.stdout,
+}: SpinnerOptions = {}): SpinnerResult => {
 	const frames = unicode ? ['◒', '◐', '◓', '◑'] : ['•', 'o', 'O', '0'];
 	const delay = unicode ? 80 : 120;
 	const isCI = process.env.CI === 'true';
@@ -770,10 +781,10 @@ export const spinner = ({ indicator = 'dots' }: SpinnerOptions = {}) => {
 
 	const clearPrevMessage = () => {
 		if (_prevMessage === undefined) return;
-		if (isCI) process.stdout.write('\n');
+		if (isCI) output.write('\n');
 		const prevLines = _prevMessage.split('\n');
-		process.stdout.write(cursor.move(-999, prevLines.length - 1));
-		process.stdout.write(erase.down(prevLines.length));
+		output.write(cursor.move(-999, prevLines.length - 1));
+		output.write(erase.down(prevLines.length));
 	};
 
 	const parseMessage = (msg: string): string => {
@@ -789,10 +800,10 @@ export const spinner = ({ indicator = 'dots' }: SpinnerOptions = {}) => {
 
 	const start = (msg = ''): void => {
 		isSpinnerActive = true;
-		unblock = block();
+		unblock = block({ output });
 		_message = parseMessage(msg);
 		_origin = performance.now();
-		process.stdout.write(`${color.gray(S_BAR)}\n`);
+		output.write(`${color.gray(S_BAR)}\n`);
 		let frameIndex = 0;
 		let indicatorTimer = 0;
 		registerHooks();
@@ -805,12 +816,12 @@ export const spinner = ({ indicator = 'dots' }: SpinnerOptions = {}) => {
 			const frame = color.magenta(frames[frameIndex]);
 
 			if (isCI) {
-				process.stdout.write(`${frame}  ${_message}...`);
+				output.write(`${frame}  ${_message}...`);
 			} else if (indicator === 'timer') {
-				process.stdout.write(`${frame}  ${_message} ${formatTimer(_origin)}`);
+				output.write(`${frame}  ${_message} ${formatTimer(_origin)}`);
 			} else {
 				const loadingDots = '.'.repeat(Math.floor(indicatorTimer)).slice(0, 3);
-				process.stdout.write(`${frame}  ${_message}${loadingDots}`);
+				output.write(`${frame}  ${_message}${loadingDots}`);
 			}
 
 			frameIndex = frameIndex + 1 < frames.length ? frameIndex + 1 : 0;
@@ -830,9 +841,9 @@ export const spinner = ({ indicator = 'dots' }: SpinnerOptions = {}) => {
 					: color.red(S_STEP_ERROR);
 		_message = parseMessage(msg ?? _message);
 		if (indicator === 'timer') {
-			process.stdout.write(`${step}  ${_message} ${formatTimer(_origin)}\n`);
+			output.write(`${step}  ${_message} ${formatTimer(_origin)}\n`);
 		} else {
-			process.stdout.write(`${step}  ${_message}\n`);
+			output.write(`${step}  ${_message}\n`);
 		}
 		clearHooks();
 		unblock();
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index da2a1e3c..3c92ac12 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -87,6 +87,9 @@ importers:
       is-unicode-supported:
         specifier: ^1.3.0
         version: 1.3.0
+      vitest:
+        specifier: ^1.6.0
+        version: 1.6.0(@types/node@18.16.0)
 
 packages:
 
@@ -5369,4 +5372,3 @@ snapshots:
   yocto-queue@0.1.0: {}
 
   yocto-queue@1.1.1: {}
-  
\ No newline at end of file