feat: stop spinner on process exit

Stops the spinner when `SIGTERM` or `SIGINT` is received.

src/index.ts

@@ -1,5 +1,6 @@
 import * as constants from './constants';
 import {countLines} from './string-lines';
+import process from 'node:process';
 
 export type Formatter = (input: string) => string;
 
@@ -49,6 +50,7 @@ export class Spinner {
     if (process.stdout.getWindowSize) this.terminalWidth = process.stdout.getWindowSize()[0];
     this.currentSymbol = this.frames[0];
     this.framesLineCountCache.fill(-1);
+    this.addListeners();
   }
 
   tick() {
@@ -64,6 +66,22 @@ export class Spinner {
     process.stdout.write(constants.CLEAR_LINE);
   }
 
+  private onProcessExit = () => {
+    if (this.running) {
+      this.stop();
+    }
+  };
+
+  private addListeners() {
+    process.once('SIGTERM', this.onProcessExit);
+    process.once('SIGINT', this.onProcessExit);
+  }
+
+  private clearListeners() {
+    process.off('SIGTERM', this.onProcessExit);
+    process.off('SIGINT', this.onProcessExit);
+  }
+
   private getLineCount(output: string) {
     let amount = this.framesLineCountCache[this.frameIndex];
     if (amount !== -1) return amount;
@@ -128,6 +146,7 @@ export class Spinner {
   stop() {
     this.clearMultiLineOutput();
     this.end(false);
+    this.clearListeners();
   }
 
   private end(newLine = true) {

src/test/spinner-test.ts

@@ -3,6 +3,7 @@ import {test} from 'node:test';
 import {Spinner, Symbols} from '..';
 import {createFinishingRenderedLine, createRenderedLine, interceptStdout} from './utils.js';
 import * as constants from '../constants';
+import process from 'node:process';
 
 async function testEndMethod(method: keyof Symbols, type: 'str' | 'obj', customSymbol?: string) {
   const stdout = await interceptStdout(async () => {
@@ -60,6 +61,18 @@ test('end methods', async (t) => {
 
     assert.equal(stdout, createFinishingRenderedLine('', ''));
   });
+
+  await t.test('process exit', async () => {
+    const stdout = await interceptStdout(async () => {
+      const spinner = new Spinner();
+      spinner.start();
+      // TODO (43081j): maybe this'll spook other things? if something is
+      // listening for SIGTERM
+      process.emit('SIGTERM');
+    });
+
+    assert.equal(stdout, constants.CLEAR_LINE + constants.SHOW_CURSOR);
+  });
 });
 
 async function testSpinner(frames?: string[], text?: string, symbolFormatter?: (v: string) => string) {