Fix Eleventy plugin error with certain configuration file formats (#1112)

Author: aarongoldenthal

packages/knip/fixtures/plugins/eleventy4/.eleventy.js

@@ -0,0 +1,14 @@
+// biome-ignore lint/suspicious/noRedundantUseStrict:  fixture festa
+'use strict';
+
+// biome-ignore lint/complexity/useArrowFunction:  fixture festa
+module.exports = async function (eleventyConfig) {
+  eleventyConfig.addPassthroughCopy('./src/assets/');
+};
+
+module.exports.config = {
+  dir: {
+    input: 'src',
+    data: '_siteData',
+  },
+};

packages/knip/fixtures/plugins/eleventy4/node_modules/@11ty/eleventy/index.js

@@ -0,0 +1,11 @@
+{
+  "name": "@plugins/eleventy4",
+  "scripts": {
+    "start": "npx @11ty/eleventy --serve",
+    "build": "npx @11ty/eleventy",
+    "build:website:watch": "eleventy --serve --port=2023"
+  },
+  "devDependencies": {
+    "@11ty/eleventy": "*"
+  }
+}

packages/knip/fixtures/plugins/eleventy4/node_modules/@11ty/eleventy/package.json

@@ -0,0 +1,5 @@
+const data = {
+  title: 'Eleventy',
+};
+
+module.exports = data;

packages/knip/fixtures/plugins/eleventy4/package.json

@@ -28,7 +28,7 @@ const resolveConfig: ResolveConfig<EleventyConfigOrFn> = async (localConfig, opt
 
   const inputDir = localConfig?.dir?.input || defaultEleventyConfig.dir.input;
   const dataDir = localConfig?.dir?.data || defaultEleventyConfig.dir.data;
-  const templateFormats = localConfig.templateFormats || defaultEleventyConfig.templateFormats;
+  const templateFormats = localConfig?.templateFormats || defaultEleventyConfig.templateFormats;
 
   const exts = DEFAULT_EXTENSIONS.map(extname => extname.slice(1)).join(',');
   const copiedEntries = new Set<string>();

packages/knip/fixtures/plugins/eleventy4/src/_siteData/global.cjs

@@ -0,0 +1,26 @@
+import { test } from 'bun:test';
+import assert from 'node:assert/strict';
+import { main } from '../../src/index.js';
+import { resolve } from '../../src/util/path.js';
+import baseArguments from '../helpers/baseArguments.js';
+import baseCounters from '../helpers/baseCounters.js';
+
+const cwd = resolve('fixtures/plugins/eleventy4');
+
+// Uses a config file with default and `config` export. While this is not
+// currently supported, this test ensures that an error is not thrown.
+test('Find dependencies with the Eleventy plugin (4)', async () => {
+  const { counters } = await main({
+    ...baseArguments,
+    cwd,
+  });
+
+  assert.deepEqual(counters, {
+    ...baseCounters,
+    // One file is found because the `config` export is not used, so the
+    // default `config.dir.data` directory is used instead.
+    files: 1,
+    processed: 3,
+    total: 3,
+  });
+});