feat: vitest use client and server side testing for kit

.changeset/thirty-ducks-buy.md

@@ -0,0 +1,5 @@
+---
+'sv': patch
+---
+
+feat: `vitest` use client and server side testing for `kit`

packages/addons/vitest-addon/index.ts

@@ -1,16 +1,19 @@
 import { dedent, defineAddon, log } from '@sveltejs/cli-core';
-import { common, exports, imports, object } from '@sveltejs/cli-core/js';
+import { array, common, exports, functions, imports, object } from '@sveltejs/cli-core/js';
 import { parseJson, parseScript } from '@sveltejs/cli-core/parsers';
 
 export default defineAddon({
 	id: 'vitest',
 	shortDescription: 'unit testing',
 	homepage: 'https://vitest.dev',
 	options: {},
-	run: ({ sv, typescript }) => {
+	run: ({ sv, typescript, kit }) => {
 		const ext = typescript ? 'ts' : 'js';
 
 		sv.devDependency('vitest', '^2.0.4');
+		sv.devDependency('@testing-library/svelte', '^5.2.4');
+		sv.devDependency('@testing-library/jest-dom', '^6.6.3');
+		sv.devDependency('jsdom', '^25.0.1');
 
 		sv.file('package.json', (content) => {
 			const { data, generateCode } = parseJson(content);
@@ -39,62 +42,109 @@ export default defineAddon({
 			`;
 		});
 
-		sv.file(`vite.config.${ext}`, (content) => {
-			const { ast, generateCode } = parseScript(content);
+		if (kit) {
+			sv.file(`${kit.routesDirectory}/page.svelte.test.${ext}`, (content) => {
+				if (content) return content;
 
-			// find `defineConfig` import declaration for "vite"
-			const importDecls = ast.body.filter((n) => n.type === 'ImportDeclaration');
-			const defineConfigImportDecl = importDecls.find(
-				(importDecl) =>
-					(importDecl.source.value === 'vite' || importDecl.source.value === 'vitest/config') &&
-					importDecl.importKind === 'value' &&
-					importDecl.specifiers?.some(
-						(specifier) =>
-							specifier.type === 'ImportSpecifier' && specifier.imported.name === 'defineConfig'
-					)
-			);
-
-			// we'll need to replace the "vite" import for a "vitest/config" import.
-			// if `defineConfig` is the only specifier in that "vite" import, remove the entire import declaration
-			if (defineConfigImportDecl?.specifiers?.length === 1) {
-				const idxToRemove = ast.body.indexOf(defineConfigImportDecl);
-				ast.body.splice(idxToRemove, 1);
-			} else {
-				// otherwise, just remove the `defineConfig` specifier
-				const idxToRemove = defineConfigImportDecl?.specifiers?.findIndex(
-					(s) => s.type === 'ImportSpecifier' && s.imported.name === 'defineConfig'
-				);
-				if (idxToRemove) defineConfigImportDecl?.specifiers?.splice(idxToRemove, 1);
-			}
+				return dedent`
+						import { describe,test, expect } from 'vitest';
+						import '@testing-library/jest-dom';
+						import { render, screen } from '@testing-library/svelte';
+						import Page from  './+page.svelte';
+
+						describe('/+page.svelte', () => {
+							test('should render h1', () => {
+								render(Page);
+								expect(screen.getByRole('heading', {level:1})).toBeInTheDocument();
+							})
+						})
+					`;
+			});
+		} else {
+			sv.file(`src/App.svelte.test.${ext}`, (content) => {
+				if (content) return content;
+
+				return dedent`
+						import { describe,test, expect } from 'vitest';
+						import '@testing-library/jest-dom';
+						import { render, screen } from '@testing-library/svelte';
+						import App from  './App.svelte';
+
+						describe('App.svelte', () => {
+							test('should render h1', () => {
+								render(App);
+								expect(screen.getByRole('heading', {level:1})).toBeInTheDocument();
+							})
+						})
+					`;
+			});
+		}
+
+		sv.file(`vitest-setup-client.${ext}`, (content) => {
+			if (content) return content;
+
+			return dedent`
+					import '@testing-library/jest-dom/vitest';
+					import {vi} from 'vitest';
 
-			const config = common.expressionFromString('defineConfig({})');
-			const defaultExport = exports.defaultExport(ast, config);
+					// add global mocks here, i.e. for sveltekit '$app/stores'
 
-			const test = object.create({
-				include: common.expressionFromString("['src/**/*.{test,spec}.{js,ts}']")
+					// needed for svelte/motion that exports new MediaQuery which calls window.matchMedia eagerly
+					Object.defineProperty(window, "matchMedia", {
+						writable: true,
+						enumerable: true,
+						value: vi.fn().mockImplementation((query) => ({
+							matches: false,
+							media: query,
+							onchange: null,
+							addListener: vi.fn(), // deprecated
+							removeListener: vi.fn(), // deprecated
+							addEventListener: vi.fn(),
+							removeEventListener: vi.fn(),
+							dispatchEvent: vi.fn(),
+						})),
+					});
+				`;
+		});
+
+		sv.file(`vitest.workspace.${ext}`, (content) => {
+			const { ast, generateCode } = parseScript(content);
+
+			imports.addNamed(ast, 'vitest/config', { defineWorkspace: 'defineWorkspace' });
+			imports.addNamed(ast, '@testing-library/svelte/vite', { svelteTesting: 'svelteTesting' });
+
+			const clientObjectExpression = object.create({
+				extends: common.createLiteral(`./vite.config.${ext}`),
+				plugins: common.expressionFromString('[svelteTesting()]'),
+				test: object.create({
+					name: common.createLiteral('client'),
+					environment: common.createLiteral('jsdom'),
+					clearMocks: common.expressionFromString('true'),
+					include: common.expressionFromString("['src/**/*.svelte.{test,spec}.{js,ts}']"),
+					exclude: common.expressionFromString("['src/lib/server/**']"),
+					setupFiles: common.expressionFromString(`['./vitest-setup-client.${ext}']`)
+				})
+			});
+			const serverObjectExpression = object.create({
+				extends: common.createLiteral(`./vite.config.${ext}`),
+				test: object.create({
+					name: common.createLiteral('server'),
+					environment: common.createLiteral('node'),
+					include: common.expressionFromString("['src/**/*.{test,spec}.{js,ts}']"),
+					exclude: common.expressionFromString("['src/**/*.svelte.{test,spec}.{js,ts}']")
+				})
 			});
 
-			// uses the `defineConfig` helper
-			if (
-				defaultExport.value.type === 'CallExpression' &&
-				defaultExport.value.arguments[0]?.type === 'ObjectExpression'
-			) {
-				// if the previous `defineConfig` was aliased, reuse the alias for the "vitest/config" import
-				const importSpecifier = defineConfigImportDecl?.specifiers?.find(
-					(sp) => sp.type === 'ImportSpecifier' && sp.imported.name === 'defineConfig'
-				);
-				const defineConfigAlias = (importSpecifier?.local?.name ?? 'defineConfig') as string;
-				imports.addNamed(ast, 'vitest/config', { defineConfig: defineConfigAlias });
-
-				object.properties(defaultExport.value.arguments[0], { test });
-			} else if (defaultExport.value.type === 'ObjectExpression') {
-				// if the config is just an object expression, just add the property
-				object.properties(defaultExport.value, { test });
-			} else {
-				// unexpected config shape
+			const defineWorkspaceFallback = functions.call('defineWorkspace', []);
+			const { value: defineWorkspaceCall } = exports.defaultExport(ast, defineWorkspaceFallback);
+			if (defineWorkspaceCall.type !== 'CallExpression') {
 				log.warn('Unexpected vite config for vitest add-on. Could not update.');
 			}
 
+			const workspaceArray = functions.argumentByIndex(defineWorkspaceCall, 0, array.createEmpty());
+			array.push(workspaceArray, clientObjectExpression);
+			array.push(workspaceArray, serverObjectExpression);
+
 			return generateCode();
 		});
 	}