From 2990914cfd3e9305a92a4554cb691bad91485774 Mon Sep 17 00:00:00 2001
From: NullVoxPopuli <199018+NullVoxPopuli@users.noreply.github.com>
Date: Fri, 14 Jul 2023 13:31:05 -0400
Subject: [PATCH 01/10] Add some fixture utils and assert that the
 .prettierrc.js is generated correctly for all tests, ensuring that the
 fixture utils work

---
 tests/.eslintignore                   |  1 +
 tests/.prettierignore                 |  1 +
 tests/assertions.ts                   | 44 ++++++++++++++++++++++++++-
 tests/fixtures/default/.prettierrc.js |  5 +++
 tests/utils.ts                        | 20 ++++++++++++
 5 files changed, 70 insertions(+), 1 deletion(-)
 create mode 100644 tests/.eslintignore
 create mode 100644 tests/.prettierignore
 create mode 100644 tests/fixtures/default/.prettierrc.js

diff --git a/tests/.eslintignore b/tests/.eslintignore
new file mode 100644
index 00000000..67fc140b
--- /dev/null
+++ b/tests/.eslintignore
@@ -0,0 +1 @@
+fixtures/
diff --git a/tests/.prettierignore b/tests/.prettierignore
new file mode 100644
index 00000000..67fc140b
--- /dev/null
+++ b/tests/.prettierignore
@@ -0,0 +1 @@
+fixtures/
diff --git a/tests/assertions.ts b/tests/assertions.ts
index 1cdbee83..f953355d 100644
--- a/tests/assertions.ts
+++ b/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 +51,45 @@ export async function assertGeneratedCorrectly({
 
     expect(await fse.pathExists(pathToFile), `${pathToFile} exists`).toBe(true);
   }
+
+  await matchesFixture('.prettierrc.js', { cwd: projectRoot });
+}
+
+export async function matchesFixture(
+  /**
+   * Project-relative file to test against
+   */
+  testFilePath: string,
+  options?: {
+    /**
+     * Which fixture set to use
+     */
+    scenario?: string;
+    /**
+     * By default, the file used will be the same as the testFilePath, but
+     * in the fixtures directory under the (maybe) specified scenario.
+     * this can be overridden, if needed.
+     * (like if you're testFilePath is deep with in an existing monorepo, and wouldn't
+     *   inherently match our default-project structure used in the fixtures)
+     */
+    file?: string;
+
+    /**
+     * The working directory to use for the relative paths. Defaults to process.cwd() (node default)
+     */
+    cwd?: string;
+  }
+) {
+  let scenario = options?.scenario ?? 'default';
+  let fixtureFile = options?.file ?? testFilePath;
+
+  if (options?.cwd) {
+    testFilePath = path.join(options.cwd, testFilePath);
+    fixtureFile = path.join(options.cwd, fixtureFile);
+  }
+
+  let sourceContents = await fs.readFile(testFilePath);
+  let fixtureContents = await fixture(fixtureFile, { scenario });
+
+  expect(sourceContents).to.equal(fixtureContents, `${testFilePath} matches ${fixtureFile}`);
 }
diff --git a/tests/fixtures/default/.prettierrc.js b/tests/fixtures/default/.prettierrc.js
new file mode 100644
index 00000000..534e6d35
--- /dev/null
+++ b/tests/fixtures/default/.prettierrc.js
@@ -0,0 +1,5 @@
+'use strict';
+
+module.exports = {
+  singleQuote: true,
+};
diff --git a/tests/utils.ts b/tests/utils.ts
index 2067da71..c2f6d1a1 100644
--- a/tests/utils.ts
+++ b/tests/utils.ts
@@ -8,9 +8,29 @@ 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.join(fixturesPath, scenario, file);
+  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);

From 3787585bd3bd179734d7aa1fcb002aa046c95ce7 Mon Sep 17 00:00:00 2001
From: NullVoxPopuli <199018+NullVoxPopuli@users.noreply.github.com>
Date: Fri, 14 Jul 2023 14:41:03 -0400
Subject: [PATCH 02/10] toString the buffer

---
 tests/assertions.ts                    | 5 ++++-
 tests/smoke-tests/--typescript.test.ts | 3 ++-
 tests/utils.ts                         | 2 +-
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/tests/assertions.ts b/tests/assertions.ts
index f953355d..c204d68d 100644
--- a/tests/assertions.ts
+++ b/tests/assertions.ts
@@ -91,5 +91,8 @@ export async function matchesFixture(
   let sourceContents = await fs.readFile(testFilePath);
   let fixtureContents = await fixture(fixtureFile, { scenario });
 
-  expect(sourceContents).to.equal(fixtureContents, `${testFilePath} matches ${fixtureFile}`);
+  expect(sourceContents.toString()).to.equal(
+    fixtureContents,
+    `${testFilePath} matches ${fixtureFile}`
+  );
 }
diff --git a/tests/smoke-tests/--typescript.test.ts b/tests/smoke-tests/--typescript.test.ts
index b0c07c60..57328eab 100644
--- a/tests/smoke-tests/--typescript.test.ts
+++ b/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 () => {
diff --git a/tests/utils.ts b/tests/utils.ts
index c2f6d1a1..50ec6093 100644
--- a/tests/utils.ts
+++ b/tests/utils.ts
@@ -25,7 +25,7 @@ export async function fixture(
   }
 ) {
   let scenario = options?.scenario ?? 'default';
-  let fixtureFilePath = path.join(fixturesPath, scenario, file);
+  let fixtureFilePath = path.isAbsolute(file) ? file : path.join(fixturesPath, scenario, file);
   let contents = await fs.readFile(fixtureFilePath);
 
   return contents.toString();

From 72154cb03becd89c5310c26e6c850a889ec3dc83 Mon Sep 17 00:00:00 2001
From: NullVoxPopuli <199018+NullVoxPopuli@users.noreply.github.com>
Date: Sat, 15 Jul 2023 11:52:22 -0400
Subject: [PATCH 03/10] Move lint ignore entries to the directories where
 eslint and prettier are ran from. ignore files do not cascade

---
 .eslintignore         | 1 +
 .prettierignore       | 1 +
 tests/.eslintignore   | 1 -
 tests/.prettierignore | 1 -
 4 files changed, 2 insertions(+), 2 deletions(-)
 create mode 100644 .prettierignore
 delete mode 100644 tests/.eslintignore
 delete mode 100644 tests/.prettierignore

diff --git a/.eslintignore b/.eslintignore
index a37273b3..3b6f3399 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -1 +1,2 @@
 files/
+tests/fixtures/
diff --git a/.prettierignore b/.prettierignore
new file mode 100644
index 00000000..55ccdbd9
--- /dev/null
+++ b/.prettierignore
@@ -0,0 +1 @@
+tests/fixtures/
diff --git a/tests/.eslintignore b/tests/.eslintignore
deleted file mode 100644
index 67fc140b..00000000
--- a/tests/.eslintignore
+++ /dev/null
@@ -1 +0,0 @@
-fixtures/
diff --git a/tests/.prettierignore b/tests/.prettierignore
deleted file mode 100644
index 67fc140b..00000000
--- a/tests/.prettierignore
+++ /dev/null
@@ -1 +0,0 @@
-fixtures/

From 9f5046b39b06af99d47cec0342ea80be8c89ebf7 Mon Sep 17 00:00:00 2001
From: NullVoxPopuli <199018+NullVoxPopuli@users.noreply.github.com>
Date: Sat, 15 Jul 2023 12:16:08 -0400
Subject: [PATCH 04/10] Add assertion about missing fixture file

---
 tests/utils.ts | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tests/utils.ts b/tests/utils.ts
index 50ec6093..19c8ab8d 100644
--- a/tests/utils.ts
+++ b/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';
@@ -26,6 +27,14 @@ export async function fixture(
 ) {
   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 ${fixtureFilePath} does not exist. To make this work, place a new file ${fixtureFilePath} in the tests/fixtures/${scenario} directory`
+  );
+
   let contents = await fs.readFile(fixtureFilePath);
 
   return contents.toString();

From 8d73b488744f915ae7fc1889253bb814fda89902 Mon Sep 17 00:00:00 2001
From: NullVoxPopuli <199018+NullVoxPopuli@users.noreply.github.com>
Date: Sat, 15 Jul 2023 12:58:07 -0400
Subject: [PATCH 05/10] Improve error message

---
 tests/utils.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/utils.ts b/tests/utils.ts
index 19c8ab8d..27a4b8cd 100644
--- a/tests/utils.ts
+++ b/tests/utils.ts
@@ -32,7 +32,7 @@ export async function fixture(
 
   assert(
     exists,
-    `Fixture file ${fixtureFilePath} does not exist. To make this work, place a new file ${fixtureFilePath} in the tests/fixtures/${scenario} directory`
+    `Fixture file ${file} does not exist. To make this work, place a new file ${file} in the tests/fixtures/${scenario} directory`
   );
 
   let contents = await fs.readFile(fixtureFilePath);

From 4a82bb9096e3299f084375748540d465baae52f9 Mon Sep 17 00:00:00 2001
From: NullVoxPopuli <199018+NullVoxPopuli@users.noreply.github.com>
Date: Sat, 15 Jul 2023 13:00:15 -0400
Subject: [PATCH 06/10] Improve error message

---
 tests/utils.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/utils.ts b/tests/utils.ts
index 27a4b8cd..9c0341d3 100644
--- a/tests/utils.ts
+++ b/tests/utils.ts
@@ -32,7 +32,7 @@ export async function fixture(
 
   assert(
     exists,
-    `Fixture file ${file} does not exist. To make this work, place a new file ${file} in the tests/fixtures/${scenario} directory`
+    `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);

From 3852609be6db1186c5ed3003d48f251c3e2298cd Mon Sep 17 00:00:00 2001
From: NullVoxPopuli <199018+NullVoxPopuli@users.noreply.github.com>
Date: Sat, 15 Jul 2023 16:11:29 -0400
Subject: [PATCH 07/10] Demonstrate usage with fixturify

---
 tests/assertions.ts                                  | 12 ++++++++----
 .../custom-locations.test.ts                         |  8 ++------
 .../within-existing-monorepo/defaults.test.ts        |  7 ++-----
 3 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/tests/assertions.ts b/tests/assertions.ts
index c204d68d..f1461ed4 100644
--- a/tests/assertions.ts
+++ b/tests/assertions.ts
@@ -85,14 +85,18 @@ export async function matchesFixture(
 
   if (options?.cwd) {
     testFilePath = path.join(options.cwd, testFilePath);
-    fixtureFile = path.join(options.cwd, fixtureFile);
   }
 
-  let sourceContents = await fs.readFile(testFilePath);
+  let sourceContents = (await fs.readFile(testFilePath)).toString();
   let fixtureContents = await fixture(fixtureFile, { scenario });
 
-  expect(sourceContents.toString()).to.equal(
-    fixtureContents,
+  /**
+   * 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}`
   );
 }
diff --git a/tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts b/tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts
index 786616c9..09a99435 100644
--- a/tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts
+++ b/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', () => {
diff --git a/tests/smoke-tests/within-existing-monorepo/defaults.test.ts b/tests/smoke-tests/within-existing-monorepo/defaults.test.ts
index ee894988..b543eef2 100644
--- a/tests/smoke-tests/within-existing-monorepo/defaults.test.ts
+++ b/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) {

From 6ea52bcf3d7cc6e9f9175874858c7f53597ead28 Mon Sep 17 00:00:00 2001
From: NullVoxPopuli <199018+NullVoxPopuli@users.noreply.github.com>
Date: Sun, 16 Jul 2023 10:23:39 -0400
Subject: [PATCH 08/10] Rename fixture to readFixture and add a comment block
 describe how the fixtures / scenarios work

---
 tests/assertions.ts |  4 ++--
 tests/utils.ts      | 10 +++++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/tests/assertions.ts b/tests/assertions.ts
index f1461ed4..94783f4b 100644
--- a/tests/assertions.ts
+++ b/tests/assertions.ts
@@ -3,7 +3,7 @@ import fs from 'node:fs/promises';
 import path from 'node:path';
 import { expect } from 'vitest';
 
-import { fixture, packageJsonAt } from './utils.js';
+import { packageJsonAt, readFixture } from './utils.js';
 
 interface AssertGeneratedOptions {
   projectRoot: string;
@@ -88,7 +88,7 @@ export async function matchesFixture(
   }
 
   let sourceContents = (await fs.readFile(testFilePath)).toString();
-  let fixtureContents = await fixture(fixtureFile, { scenario });
+  let fixtureContents = await readFixture(fixtureFile, { scenario });
 
   /**
    * We trim because whether or not the source or fixture has
diff --git a/tests/utils.ts b/tests/utils.ts
index 9c0341d3..69b32aab 100644
--- a/tests/utils.ts
+++ b/tests/utils.ts
@@ -13,7 +13,15 @@ const fixturesPath = path.join(__dirname, 'fixtures');
 
 export const SUPPORTED_PACKAGE_MANAGERS = ['npm', 'yarn', 'pnpm'] as const;
 
-export async function fixture(
+/**
+ * Returns the contents of a file from the "tests/fixtures" directory.
+ * The "tests/fixtures" directory contains sub-directories, "scenarios".
+ * This is we can have different sets of fixtures, depending on what we're testing.
+ *
+ * The default scenario is "default", and represents the the file contents when we provide
+ * no arguments to the blueprint
+ */
+export async function readFixture(
   /**
    * Which file within in the fixture-set / scenario to read
    */

From aa1bb47756d6ddff1d5f0d0cae45e6b92725ab87 Mon Sep 17 00:00:00 2001
From: NullVoxPopuli <199018+NullVoxPopuli@users.noreply.github.com>
Date: Sun, 16 Jul 2023 10:39:55 -0400
Subject: [PATCH 09/10] setting up an addon-creating helper so we can more
 easily manage the creation of addons

will need to propagate through the existing tests
but that can happen in other PRs
---
 tests/assertions.ts                           |   3 +-
 tests/fixtures.ts                             |  81 ++++++++++++
 tests/smoke-tests/--addon-only.test.ts        |  28 ++---
 .../custom-locations.test.ts                  |   5 +-
 .../within-existing-monorepo/defaults.test.ts |   4 +-
 tests/test-helpers.ts                         | 115 ++++++++++++++++++
 tests/utils.ts                                |  37 ------
 7 files changed, 212 insertions(+), 61 deletions(-)
 create mode 100644 tests/fixtures.ts
 create mode 100644 tests/test-helpers.ts

diff --git a/tests/assertions.ts b/tests/assertions.ts
index 94783f4b..4c865f40 100644
--- a/tests/assertions.ts
+++ b/tests/assertions.ts
@@ -3,7 +3,8 @@ import fs from 'node:fs/promises';
 import path from 'node:path';
 import { expect } from 'vitest';
 
-import { packageJsonAt, readFixture } from './utils.js';
+import { readFixture } from './fixtures.js';
+import { packageJsonAt } from './utils.js';
 
 interface AssertGeneratedOptions {
   projectRoot: string;
diff --git a/tests/fixtures.ts b/tests/fixtures.ts
new file mode 100644
index 00000000..cc814a07
--- /dev/null
+++ b/tests/fixtures.ts
@@ -0,0 +1,81 @@
+import fse from 'fs-extra';
+import assert from 'node:assert';
+import fs from 'node:fs/promises';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+
+const fixturesPath = path.join(__dirname, 'fixtures');
+
+/**
+ * Returns the contents of a file from the "tests/fixtures" directory.
+ * The "tests/fixtures" directory contains sub-directories, "scenarios".
+ * This is we can have different sets of fixtures, depending on what we're testing.
+ *
+ * The default scenario is "default", and represents the the file contents when we provide
+ * no arguments to the blueprint
+ */
+export async function readFixture(
+  /**
+   * 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 copyFixture(
+  /**
+   * Which file within the fixture-set / scenario to copy
+   */
+  newFile: 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 ?? newFile;
+
+  if (options?.cwd) {
+    newFile = path.join(options.cwd, newFile);
+  }
+
+  let fixtureContents = await readFixture(fixtureFile, { scenario });
+
+  await fse.mkdir(path.dirname(newFile), { recursive: true });
+  await fs.writeFile(newFile, fixtureContents);
+}
diff --git a/tests/smoke-tests/--addon-only.test.ts b/tests/smoke-tests/--addon-only.test.ts
index 5605f17a..a96ff47f 100644
--- a/tests/smoke-tests/--addon-only.test.ts
+++ b/tests/smoke-tests/--addon-only.test.ts
@@ -1,34 +1,24 @@
 import fse from 'fs-extra';
-import fs from 'node:fs/promises';
 import path from 'node:path';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
-import { createAddon, createTmp, install, runScript } from '../utils.js';
+import { AddonHelper } from '../test-helpers.js';
 
 describe('--addon-only', () => {
-  let cwd = '';
-  let tmpDir = '';
+  let helper = new AddonHelper({ packageManager: 'pnpm', args: ['--addon-only'] });
 
   beforeAll(async () => {
-    tmpDir = await createTmp();
-
-    let { name } = await createAddon({
-      args: ['--addon-only', '--pnpm=true'],
-      options: { cwd: tmpDir },
-    });
-
-    cwd = path.join(tmpDir, name);
-
-    await install({ cwd, packageManager: 'pnpm' });
+    await helper.setup();
+    await helper.installDeps();
   });
 
   afterAll(async () => {
-    fs.rm(tmpDir, { recursive: true, force: true });
+    await helper.clean();
   });
 
   it('is not a monorepo', async () => {
-    let hasPnpmWorkspace = await fse.pathExists(path.join(cwd, 'pnpm-workspace.yaml'));
-    let packageJson = await fse.readJson(path.join(cwd, 'package.json'));
+    let hasPnpmWorkspace = await fse.pathExists(path.join(helper.cwd, 'pnpm-workspace.yaml'));
+    let packageJson = await fse.readJson(path.join(helper.cwd, 'package.json'));
 
     expect(hasPnpmWorkspace).toBe(false);
     // Pnpm doesn't use this field, but it's good that it doesn't exist.
@@ -36,13 +26,13 @@ describe('--addon-only', () => {
   });
 
   it('can build', async () => {
-    let { exitCode } = await runScript({ cwd, script: 'build', packageManager: 'pnpm' });
+    let { exitCode } = await helper.build();
 
     expect(exitCode).toEqual(0);
   });
 
   it('has passing lints', async () => {
-    let { exitCode } = await runScript({ cwd, script: 'lint', packageManager: 'pnpm' });
+    let { exitCode } = await helper.build();
 
     expect(exitCode).toEqual(0);
   });
diff --git a/tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts b/tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts
index 09a99435..4a5becd1 100644
--- a/tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts
+++ b/tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts
@@ -4,10 +4,11 @@ import path from 'node:path';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
 import { assertGeneratedCorrectly } from '../../assertions.js';
-import { createAddon, createTmp, fixture, install, runScript } from '../../utils.js';
+import { readFixture } from '../../fixtures.js';
+import { createAddon, createTmp, install, runScript } from '../../utils.js';
 
 let commonFixtures = {
-  '.prettierrc.js': await fixture('.prettierrc.js'),
+  '.prettierrc.js': await readFixture('.prettierrc.js'),
 };
 
 describe('custom locations', () => {
diff --git a/tests/smoke-tests/within-existing-monorepo/defaults.test.ts b/tests/smoke-tests/within-existing-monorepo/defaults.test.ts
index b543eef2..b507f088 100644
--- a/tests/smoke-tests/within-existing-monorepo/defaults.test.ts
+++ b/tests/smoke-tests/within-existing-monorepo/defaults.test.ts
@@ -4,17 +4,17 @@ import path from 'node:path';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
 import { assertGeneratedCorrectly } from '../../assertions.js';
+import { readFixture } from '../../fixtures.js';
 import {
   createAddon,
   createTmp,
-  fixture,
   install,
   runScript,
   SUPPORTED_PACKAGE_MANAGERS,
 } from '../../utils.js';
 
 let commonFixtures = {
-  '.prettierrc.js': await fixture('.prettierrc.js'),
+  '.prettierrc.js': await readFixture('.prettierrc.js'),
 };
 
 for (let packageManager of SUPPORTED_PACKAGE_MANAGERS) {
diff --git a/tests/test-helpers.ts b/tests/test-helpers.ts
new file mode 100644
index 00000000..3c59abb1
--- /dev/null
+++ b/tests/test-helpers.ts
@@ -0,0 +1,115 @@
+import assert from 'node:assert';
+import fs from 'node:fs/promises';
+import path from 'node:path';
+
+import { matchesFixture } from './assertions.js';
+import { copyFixture } from './fixtures.js';
+import { createAddon, createTmp, install, runScript } from './utils.js';
+
+const DEBUG = process.env.DEBUG === 'true';
+
+/**
+ * Helps with common addon testing concerns.
+ * tl;dr:
+ *   it's a wrapper around ember addon -b (so we can pass our flags with less duplication)
+ *   it lets us set compare against a fixture set / scenario
+ *
+ * To DEBUG the intermediate output (in tmp),
+ * re-start your tests with `DEBUG=true`, and the tmpdir will be printed
+ * as well as the `clean` function will not run so that if a test finishes,
+ * you can still inspect the folder contents
+ *
+ */
+export class AddonHelper {
+  #cwd?: string;
+  #tmpDir?: string;
+  #scenario: string;
+  #packageManager: 'npm' | 'pnpm' | 'yarn';
+  #args: string[];
+  #fixtures: AddonFixtureHelper | undefined;
+
+  constructor(options: {
+    args?: string[];
+    scenario?: string;
+    packageManager: 'pnpm' | 'npm' | 'yarn';
+  }) {
+    this.#args = options.args || [];
+    this.#scenario = options.scenario || 'default';
+    this.#packageManager = options.packageManager;
+  }
+
+  async setup() {
+    this.#tmpDir = await createTmp();
+
+    if (DEBUG) {
+      console.debug(`Debug test repo at ${this.#tmpDir}`);
+    }
+
+    let { name } = await createAddon({
+      args: this.#args,
+      options: { cwd: this.#tmpDir },
+    });
+
+    // this is the project root
+    this.#cwd = path.join(this.#tmpDir, name);
+
+    this.#fixtures = new AddonFixtureHelper({ cwd: this.#cwd, scenario: this.#scenario });
+  }
+
+  async run(scriptName: string) {
+    return await runScript({
+      cwd: this.cwd,
+      script: scriptName,
+      packageManager: this.#packageManager,
+    });
+  }
+
+  async build() {
+    return this.run('build');
+  }
+
+  async clean() {
+    if (DEBUG) return;
+
+    assert(
+      this.#tmpDir,
+      "Cannot clean without a tmpDir. Was the Addon Helper's `setup` method called to generate the addon?"
+    );
+
+    await fs.rm(this.#tmpDir, { recursive: true, force: true });
+  }
+
+  async installDeps() {
+    await install({ cwd: this.cwd, packageManager: this.#packageManager, skipPrepare: true });
+  }
+
+  get cwd() {
+    assert(this.#cwd, "Cannot get cwd. Was the Addon Helper's `setup` method called?");
+
+    return this.#cwd;
+  }
+
+  get fixtures() {
+    assert(this.#fixtures, 'Cannot get fixtures-helper. Was the Addon Helper `setup`?');
+
+    return this.#fixtures;
+  }
+}
+
+export class AddonFixtureHelper {
+  #cwd: string;
+  #scenario: string;
+
+  constructor(options: { cwd: string; scenario?: string }) {
+    this.#cwd = options.cwd;
+    this.#scenario = options.scenario || 'default';
+  }
+
+  async use(file: string) {
+    await copyFixture(file, { scenario: this.#scenario, cwd: this.#cwd });
+  }
+
+  async matches(outputFile: string) {
+    await matchesFixture(outputFile, { scenario: this.#scenario, cwd: this.#cwd });
+  }
+}
diff --git a/tests/utils.ts b/tests/utils.ts
index 69b32aab..2067da71 100644
--- a/tests/utils.ts
+++ b/tests/utils.ts
@@ -1,6 +1,5 @@
 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';
@@ -9,45 +8,9 @@ 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;
 
-/**
- * Returns the contents of a file from the "tests/fixtures" directory.
- * The "tests/fixtures" directory contains sub-directories, "scenarios".
- * This is we can have different sets of fixtures, depending on what we're testing.
- *
- * The default scenario is "default", and represents the the file contents when we provide
- * no arguments to the blueprint
- */
-export async function readFixture(
-  /**
-   * 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);

From 5d2aae963d908c72435a08f8894354a49486e6f5 Mon Sep 17 00:00:00 2001
From: NullVoxPopuli <199018+NullVoxPopuli@users.noreply.github.com>
Date: Mon, 17 Jul 2023 08:23:39 -0400
Subject: [PATCH 10/10] Move the helpers in to a directory, so they aren't
 confused with top-level config

---
 tests/helpers.ts                                      |  4 ++++
 tests/{ => helpers}/assertions.ts                     |  0
 tests/{ => helpers}/fixtures.ts                       |  2 +-
 tests/{test-helpers.ts => helpers/meta-helpers.ts}    |  0
 tests/{ => helpers}/utils.ts                          |  3 ++-
 tests/smoke-tests/--addon-location.test.ts            |  9 +++++++--
 tests/smoke-tests/--addon-only.test.ts                |  2 +-
 tests/smoke-tests/--test-app-location.test.ts         |  9 +++++++--
 tests/smoke-tests/--typescript.test.ts                |  4 ++--
 tests/smoke-tests/defaults.test.ts                    |  4 ++--
 .../within-existing-monorepo/custom-locations.test.ts | 11 ++++++++---
 .../within-existing-monorepo/defaults.test.ts         |  6 +++---
 12 files changed, 37 insertions(+), 17 deletions(-)
 create mode 100644 tests/helpers.ts
 rename tests/{ => helpers}/assertions.ts (100%)
 rename tests/{ => helpers}/fixtures.ts (97%)
 rename tests/{test-helpers.ts => helpers/meta-helpers.ts} (100%)
 rename tests/{ => helpers}/utils.ts (98%)

diff --git a/tests/helpers.ts b/tests/helpers.ts
new file mode 100644
index 00000000..ae90a921
--- /dev/null
+++ b/tests/helpers.ts
@@ -0,0 +1,4 @@
+export * from './helpers/assertions.js';
+export * from './helpers/fixtures.js';
+export * from './helpers/meta-helpers.js';
+export * from './helpers/utils.js';
diff --git a/tests/assertions.ts b/tests/helpers/assertions.ts
similarity index 100%
rename from tests/assertions.ts
rename to tests/helpers/assertions.ts
diff --git a/tests/fixtures.ts b/tests/helpers/fixtures.ts
similarity index 97%
rename from tests/fixtures.ts
rename to tests/helpers/fixtures.ts
index cc814a07..7eb68b02 100644
--- a/tests/fixtures.ts
+++ b/tests/helpers/fixtures.ts
@@ -6,7 +6,7 @@ import { fileURLToPath } from 'node:url';
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
-const fixturesPath = path.join(__dirname, 'fixtures');
+const fixturesPath = path.join(__dirname, '../fixtures');
 
 /**
  * Returns the contents of a file from the "tests/fixtures" directory.
diff --git a/tests/test-helpers.ts b/tests/helpers/meta-helpers.ts
similarity index 100%
rename from tests/test-helpers.ts
rename to tests/helpers/meta-helpers.ts
diff --git a/tests/utils.ts b/tests/helpers/utils.ts
similarity index 98%
rename from tests/utils.ts
rename to tests/helpers/utils.ts
index 2067da71..cf62a6b8 100644
--- a/tests/utils.ts
+++ b/tests/helpers/utils.ts
@@ -7,7 +7,8 @@ import { fileURLToPath } from 'node:url';
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
-const blueprintPath = path.join(__dirname, '..');
+// repo-root
+const blueprintPath = path.join(__dirname, '../..');
 
 export const SUPPORTED_PACKAGE_MANAGERS = ['npm', 'yarn', 'pnpm'] as const;
 
diff --git a/tests/smoke-tests/--addon-location.test.ts b/tests/smoke-tests/--addon-location.test.ts
index fc181738..e380ba19 100644
--- a/tests/smoke-tests/--addon-location.test.ts
+++ b/tests/smoke-tests/--addon-location.test.ts
@@ -2,8 +2,13 @@ import fs from 'node:fs/promises';
 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 {
+  assertGeneratedCorrectly,
+  createAddon,
+  createTmp,
+  install,
+  runScript,
+} from '../helpers.js';
 
 describe('--addon-location', () => {
   let cwd = '';
diff --git a/tests/smoke-tests/--addon-only.test.ts b/tests/smoke-tests/--addon-only.test.ts
index a96ff47f..c3a97766 100644
--- a/tests/smoke-tests/--addon-only.test.ts
+++ b/tests/smoke-tests/--addon-only.test.ts
@@ -2,7 +2,7 @@ import fse from 'fs-extra';
 import path from 'node:path';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
-import { AddonHelper } from '../test-helpers.js';
+import { AddonHelper } from '../helpers.js';
 
 describe('--addon-only', () => {
   let helper = new AddonHelper({ packageManager: 'pnpm', args: ['--addon-only'] });
diff --git a/tests/smoke-tests/--test-app-location.test.ts b/tests/smoke-tests/--test-app-location.test.ts
index e5bd1d0e..01e44915 100644
--- a/tests/smoke-tests/--test-app-location.test.ts
+++ b/tests/smoke-tests/--test-app-location.test.ts
@@ -2,8 +2,13 @@ import fs from 'node:fs/promises';
 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 {
+  assertGeneratedCorrectly,
+  createAddon,
+  createTmp,
+  install,
+  runScript,
+} from '../helpers.js';
 
 describe('--test-app-location', () => {
   let cwd = '';
diff --git a/tests/smoke-tests/--typescript.test.ts b/tests/smoke-tests/--typescript.test.ts
index 57328eab..a9cb843e 100644
--- a/tests/smoke-tests/--typescript.test.ts
+++ b/tests/smoke-tests/--typescript.test.ts
@@ -2,15 +2,15 @@ import fs from 'node:fs/promises';
 import path from 'node:path';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
-import { assertGeneratedCorrectly } from '../assertions.js';
 import {
+  assertGeneratedCorrectly,
   createAddon,
   createTmp,
   dirContents,
   install,
   runScript,
   SUPPORTED_PACKAGE_MANAGERS,
-} from '../utils.js';
+} from '../helpers.js';
 
 for (let packageManager of SUPPORTED_PACKAGE_MANAGERS) {
   describe(`--typescript with ${packageManager}`, () => {
diff --git a/tests/smoke-tests/defaults.test.ts b/tests/smoke-tests/defaults.test.ts
index 063fc9ba..7ad458ca 100644
--- a/tests/smoke-tests/defaults.test.ts
+++ b/tests/smoke-tests/defaults.test.ts
@@ -3,15 +3,15 @@ import fs from 'node:fs/promises';
 import path from 'node:path';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
-import { assertGeneratedCorrectly } from '../assertions.js';
 import {
+  assertGeneratedCorrectly,
   createAddon,
   createTmp,
   dirContents,
   install,
   runScript,
   SUPPORTED_PACKAGE_MANAGERS,
-} from '../utils.js';
+} from '../helpers.js';
 
 for (let packageManager of SUPPORTED_PACKAGE_MANAGERS) {
   describe(`defaults with ${packageManager}`, () => {
diff --git a/tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts b/tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts
index 4a5becd1..06fbc184 100644
--- a/tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts
+++ b/tests/smoke-tests/within-existing-monorepo/custom-locations.test.ts
@@ -3,9 +3,14 @@ import fs from 'node:fs/promises';
 import path from 'node:path';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
-import { assertGeneratedCorrectly } from '../../assertions.js';
-import { readFixture } from '../../fixtures.js';
-import { createAddon, createTmp, install, runScript } from '../../utils.js';
+import {
+  assertGeneratedCorrectly,
+  createAddon,
+  createTmp,
+  install,
+  readFixture,
+  runScript,
+} from '../../helpers.js';
 
 let commonFixtures = {
   '.prettierrc.js': await readFixture('.prettierrc.js'),
diff --git a/tests/smoke-tests/within-existing-monorepo/defaults.test.ts b/tests/smoke-tests/within-existing-monorepo/defaults.test.ts
index b507f088..9f5ad44f 100644
--- a/tests/smoke-tests/within-existing-monorepo/defaults.test.ts
+++ b/tests/smoke-tests/within-existing-monorepo/defaults.test.ts
@@ -3,15 +3,15 @@ import fs from 'node:fs/promises';
 import path from 'node:path';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
-import { assertGeneratedCorrectly } from '../../assertions.js';
-import { readFixture } from '../../fixtures.js';
 import {
+  assertGeneratedCorrectly,
   createAddon,
   createTmp,
   install,
+  readFixture,
   runScript,
   SUPPORTED_PACKAGE_MANAGERS,
-} from '../../utils.js';
+} from '../../helpers.js';
 
 let commonFixtures = {
   '.prettierrc.js': await readFixture('.prettierrc.js'),