Add some fixture utils ...

.eslintignore

@@ -1 +1,2 @@
 files/
+tests/fixtures/

.prettierignore

@@ -0,0 +1 @@
+tests/fixtures/

tests/assertions.ts

@@ -1,8 +1,9 @@
 import fse from 'fs-extra';
+import fs from 'node:fs/promises';
 import path from 'node:path';
 import { expect } from 'vitest';
 
-import { packageJsonAt } from './utils.js';
+import { fixture, packageJsonAt } from './utils.js';
 
 interface AssertGeneratedOptions {
   projectRoot: string;
@@ -50,4 +51,52 @@ export async function assertGeneratedCorrectly({
 
     expect(await fse.pathExists(pathToFile), `${pathToFile} exists`).toBe(true);
   }
+
+  await matchesFixture('.prettierrc.js', { cwd: projectRoot });
+}
+
+export async function matchesFixture(
+  /**
+   * Project-relative file to test against
+   */
+  testFilePath: string,
+  options?: {
+    /**
+     * Which fixture set to use
+     */
+    scenario?: string;
+    /**
+     * By default, the file used will be the same as the testFilePath, but
+     * in the fixtures directory under the (maybe) specified scenario.
+     * this can be overridden, if needed.
+     * (like if you're testFilePath is deep with in an existing monorepo, and wouldn't
+     *   inherently match our default-project structure used in the fixtures)
+     */
+    file?: string;
+
+    /**
+     * The working directory to use for the relative paths. Defaults to process.cwd() (node default)
+     */
+    cwd?: string;
+  }
+) {
+  let scenario = options?.scenario ?? 'default';
+  let fixtureFile = options?.file ?? testFilePath;
+
+  if (options?.cwd) {
+    testFilePath = path.join(options.cwd, testFilePath);
+  }
+
+  let sourceContents = (await fs.readFile(testFilePath)).toString();
+  let fixtureContents = await fixture(fixtureFile, { scenario });
+
+  /**
+   * We trim because whether or not the source or fixture has
+   * leading / trailing invisible characters is of no significance
+   * and is mostly a bother to get correct in testing
+   */
+  expect(sourceContents.trim()).to.equal(
+    fixtureContents.trim(),
+    `${testFilePath} matches ${fixtureFile}`
+  );
 }

tests/fixtures/default/.prettierrc.js

@@ -0,0 +1,5 @@
+'use strict';
+
+module.exports = {
+  singleQuote: true,
+};

tests/smoke-tests/--typescript.test.ts

@@ -1,3 +1,4 @@
+import fs from 'node:fs/promises';
 import path from 'node:path';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
@@ -34,7 +35,7 @@ for (let packageManager of SUPPORTED_PACKAGE_MANAGERS) {
     });
 
     afterAll(async () => {
-      // await fs.rm(tmpDir, { recursive: true, force: true });
+      await fs.rm(tmpDir, { recursive: true, force: true });
     });
 
     it('was generated correctly', async () => {

tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts

@@ -4,14 +4,10 @@ import path from 'node:path';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
 import { assertGeneratedCorrectly } from '../../assertions.js';
-import { createAddon, createTmp, install, runScript } from '../../utils.js';
+import { createAddon, createTmp, fixture, install, runScript } from '../../utils.js';
 
 let commonFixtures = {
-  '.prettierrc.js':
-    // prettier-ignore
-    'module.exports = {' + 
-        '  singleQuote: true,' + 
-        '};',
+  '.prettierrc.js': await fixture('.prettierrc.js'),
 };
 
 describe('custom locations', () => {

tests/smoke-tests/within-existing-monorepo/defaults.test.ts

@@ -7,17 +7,14 @@ import { assertGeneratedCorrectly } from '../../assertions.js';
 import {
   createAddon,
   createTmp,
+  fixture,
   install,
   runScript,
   SUPPORTED_PACKAGE_MANAGERS,
 } from '../../utils.js';
 
 let commonFixtures = {
-  '.prettierrc.js':
-    // prettier-ignore
-    'module.exports = {' + 
-        '  singleQuote: true,' + 
-        '};',
+  '.prettierrc.js': await fixture('.prettierrc.js'),
 };
 
 for (let packageManager of SUPPORTED_PACKAGE_MANAGERS) {

tests/utils.ts

@@ -1,5 +1,6 @@
 import { type Options, execa } from 'execa';
 import fse from 'fs-extra';
+import assert from 'node:assert';
 import fs from 'node:fs/promises';
 import os from 'node:os';
 import path from 'node:path';
@@ -8,9 +9,37 @@ import { fileURLToPath } from 'node:url';
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
 const blueprintPath = path.join(__dirname, '..');
+const fixturesPath = path.join(__dirname, 'fixtures');
 
 export const SUPPORTED_PACKAGE_MANAGERS = ['npm', 'yarn', 'pnpm'] as const;
 
+export async function fixture(
+  /**
+   * Which file within in the fixture-set / scenario to read
+   */
+  file: string,
+  options?: {
+    /**
+     * Which fixture set to use
+     */
+    scenario?: string;
+  }
+) {
+  let scenario = options?.scenario ?? 'default';
+  let fixtureFilePath = path.isAbsolute(file) ? file : path.join(fixturesPath, scenario, file);
+
+  let exists = await fse.pathExists(fixtureFilePath);
+
+  assert(
+    exists,
+    `Fixture file '${file}' does not exist. To make this work, place a new file '${file}' in the 'tests/fixtures/${scenario}' directory. Checked the absolute path: '${fixtureFilePath}'.`
+  );
+
+  let contents = await fs.readFile(fixtureFilePath);
+
+  return contents.toString();
+}
+
 export async function createTmp() {
   let prefix = 'v2-addon-blueprint--';
   let prefixPath = path.join(os.tmpdir(), prefix);