diff --git a/packages/toolkit/src/utils/helpers.js b/packages/toolkit/src/utils/helpers.js
index 1ff5476..7af1393 100644
--- a/packages/toolkit/src/utils/helpers.js
+++ b/packages/toolkit/src/utils/helpers.js
@@ -29,6 +29,7 @@ export const runCommand = ( tool, files, globs, args = [] ) => {
 	);
 
 	child.on( 'exit', ( code ) => {
+		process.exitCode = code ?? 1;
 		if ( code === 0 ) {
 			log.success( `Completed ${ tool } successfully.` );
 		} else {
diff --git a/packages/toolkit/tests/helpers.test.js b/packages/toolkit/tests/helpers.test.js
new file mode 100644
index 0000000..81e8f57
--- /dev/null
+++ b/packages/toolkit/tests/helpers.test.js
@@ -0,0 +1,44 @@
+import { beforeEach, afterEach, describe, expect, test, vi } from 'vitest';
+import { spawn } from 'child_process';
+import { runCommand } from '../src/utils/helpers.js';
+
+vi.mock( 'child_process', () => ( {
+	exec: vi.fn(),
+	spawn: vi.fn(),
+} ) );
+
+vi.mock( '../src/utils/logger.js', () => ( {
+	default: {
+		info: vi.fn(),
+		success: vi.fn(),
+		error: vi.fn(),
+	},
+} ) );
+
+describe( 'runCommand', () => {
+	let exitHandler;
+
+	beforeEach( () => {
+		spawn.mockReturnValue( {
+			on: vi.fn( ( event, handler ) => {
+				if ( event === 'exit' ) exitHandler = handler;
+			} ),
+		} );
+	} );
+
+	afterEach( () => {
+		process.exitCode = undefined;
+		vi.clearAllMocks();
+	} );
+
+	test.each( [
+		[ 0, 0 ],
+		[ 1, 1 ],
+		[ null, 1 ],
+	] )( 'sets process.exitCode to %s when the child exits', ( code, expected ) => {
+		runCommand( 'eslint', [], [] );
+		exitHandler( code );
+
+		expect( process.exitCode ).toBe( expected );
+	} );
+} );
diff --git a/packages/toolkit/vitest.config.mjs b/packages/toolkit/vitest.config.mjs
new file mode 100644
index 0000000..add21f1
--- /dev/null
+++ b/packages/toolkit/vitest.config.mjs
@@ -0,0 +1,9 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig( {
+	test: {
+		globals: true,
+		environment: 'node',
+		include: [ 'tests/**/*.test.js' ],
+	},
+} );
diff --git a/vitest.config.mjs b/vitest.config.mjs
index 4a07609..d82281c 100644
--- a/vitest.config.mjs
+++ b/vitest.config.mjs
@@ -5,6 +5,7 @@ export default defineConfig( {
 		projects: [
 			'packages/eslint-config/vitest.config.mjs',
 			'packages/prettier-config/vitest.config.mjs',
+			'packages/toolkit/vitest.config.mjs',
 			'packages/wp-scripts-config/vitest.config.mjs',
 		],
 	},