Fix bug where theme check would fail for theme app extensions

This bug only surfaces when a developer would manually run the theme
check against a theme app extension from the CLI. Inside the VSCode
extension we were already doing the right thing so you wouldn't notice
it there and the Shopify CLI hardcodes the check when you build your app
so you wouldn't notice it there either.

This adds some logic to where we load the config to check if we're
inside of an app by looking for two app-like config files. If so, we use
`theme-check:theme-app-extension` as our default checks rather than the
recommended. This ensures that our context is appropriately set as 'app'
instead of 'theme' and removes false positives when running the check.

Author: graygilmore

.changeset/slow-bananas-sing.md

@@ -0,0 +1,5 @@
+---
+'@shopify/theme-check-node': patch
+---
+
+Fix false positives when running theme check on theme app extensions

packages/theme-check-node/src/config/load-config.spec.ts

@@ -1,6 +1,6 @@
 import fs from 'node:fs/promises';
 import path from 'node:path';
-import { describe, it, expect, afterEach, beforeEach, assert } from 'vitest';
+import { describe, it, expect, afterEach, beforeEach, assert, vi } from 'vitest';
 import { loadConfig } from './load-config';
 import {
   allChecks,
@@ -19,6 +19,7 @@ import {
 } from '../test/test-helpers';
 import { thisNodeModuleRoot } from './installation-location';
 import { URI } from 'vscode-uri';
+import * as resolveModule from './resolve';
 
 describe('Unit: loadConfig', () => {
   let tempDir: string;
@@ -34,8 +35,31 @@ describe('Unit: loadConfig', () => {
   it('loads the recommended config by default', async () => {
     const config = await loadConfig(undefined, __dirname);
     expect(config.checks).to.eql(recommended);
+    expect(config.context).to.eql('theme');
   });
 
+  describe.each(['shopify.extension.toml', 'shopify.app.toml'])(
+    'when the root contains a %s file',
+    (fileName) => {
+      beforeEach(async () => {
+        const filePath = path.join(tempDir, fileName);
+        await fs.writeFile(filePath, '', 'utf8');
+      });
+
+      it('sets the context to app', async () => {
+        const config = await loadConfig(undefined, tempDir);
+        expect(config.context).to.eql('app');
+      });
+
+      it('calls resolveConfig with theme-check:theme-app-extension', async () => {
+        const spy = vi.spyOn(resolveModule, 'resolveConfig');
+        await loadConfig(undefined, tempDir);
+        expect(spy).toHaveBeenCalledWith('theme-check:theme-app-extension', true);
+        vi.restoreAllMocks();
+      });
+    },
+  );
+
   it('extends the recommended config by default', async () => {
     const configPath = await createMockConfigFile(tempDir, `ignore: ['src/**']`);
     const config = await loadConfig(configPath, tempDir);

packages/theme-check-node/src/config/load-config.ts

@@ -4,6 +4,7 @@ import { loadConfigDescription } from './load-config-description';
 import { resolveConfig } from './resolve';
 import { ModernIdentifier } from './types';
 import { validateConfig } from './validation';
+import fs from 'fs/promises';
 
 /**
  * Given an absolute path to a config file, this function returns
@@ -22,7 +23,18 @@ export async function loadConfig(
   root: AbsolutePath,
 ): Promise<Config> {
   if (!root) throw new Error('loadConfig cannot be called without a root argument');
-  const configDescription = await resolveConfig(configPath ?? 'theme-check:recommended', true);
+  let defaultChecks = 'theme-check:recommended';
+
+  if (!configPath) {
+    const files = await fs.readdir(root);
+    // *.extension.toml implies that we're already in the appropriate extensions
+    // directory. *.app.toml implies that we're inside the root of an app.
+    if (files.some((file) => file.endsWith('.extension.toml') || file.endsWith('.app.toml'))) {
+      defaultChecks = 'theme-check:theme-app-extension';
+    }
+  }
+
+  const configDescription = await resolveConfig(configPath ?? defaultChecks, true);
   const config = await loadConfigDescription(configDescription, root);
   validateConfig(config);
   return config;