From d76f861e72f23a730f5051c261256be7efde4e87 Mon Sep 17 00:00:00 2001
From: "Nicholas Carrigan (he/him)" <nhcarrigan@gmail.com>
Date: Thu, 31 Dec 2020 01:17:45 -0800
Subject: [PATCH] tools(client): Translation Key usage validation (#40585)

---
 client/i18n/validate-keys.js | 62 ++++++++++++++++++++++++++++++++++++
 client/package.json          |  3 +-
 2 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 client/i18n/validate-keys.js

diff --git a/client/i18n/validate-keys.js b/client/i18n/validate-keys.js
new file mode 100644
index 0000000000..b162ee3a0c
--- /dev/null
+++ b/client/i18n/validate-keys.js
@@ -0,0 +1,62 @@
+const fs = require('fs');
+const path = require('path');
+const translationsObject = require('./locales/english/translations.json');
+
+/**
+ * Function to flatten a nested object. Written specifically for
+ * our translation flow, the `namespace` value is used to create the
+ * property chains that are used in the i18n replacement scripts.
+ * @param {Object} obj
+ * @param {string} namespace
+ */
+const flattenAnObject = (obj, namespace = '') => {
+  const flattened = {};
+  Object.keys(obj).forEach(key => {
+    if (Array.isArray(obj[key])) {
+      flattened[namespace ? `${namespace}.${key}` : key] = obj[key];
+    } else if (typeof obj[key] === 'object') {
+      Object.assign(
+        flattened,
+        flattenAnObject(obj[key], namespace ? `${namespace}.${key}` : key)
+      );
+    } else {
+      flattened[namespace ? `${namespace}.${key}` : key] = obj[key];
+    }
+  });
+  return flattened;
+};
+
+const flattenedSchema = flattenAnObject(translationsObject);
+
+const keyStrings = Object.keys(flattenedSchema);
+
+/**
+ * Recursively read through the directory, grabbing .js files
+ * in each nested subdirectory and concatenating them all in
+ * to one string.
+ * @param {String} filePath
+ */
+const readComponentCode = filePath => {
+  let code = '';
+  const isItFolder = fs.lstatSync(filePath).isDirectory();
+  if (isItFolder) {
+    const contents = fs.readdirSync(filePath);
+    contents.forEach(file => {
+      code += readComponentCode(path.join(filePath + '/' + file));
+    });
+  } else {
+    if (!filePath.endsWith('.js') || filePath.endsWith('.test.js')) {
+      return '';
+    }
+    code += fs.readFileSync(filePath);
+  }
+  return code;
+};
+
+const clientCodebase = readComponentCode(path.join(process.cwd() + '/src'));
+
+for (const key of keyStrings) {
+  if (!clientCodebase.includes(key)) {
+    console.warn(`The translation key '${key}' appears to be unused.`);
+  }
+}
diff --git a/client/package.json b/client/package.json
index fea2f796e9..0cad4d3e3b 100644
--- a/client/package.json
+++ b/client/package.json
@@ -98,7 +98,8 @@
     "prestand-alone": "npm run prebuild",
     "stand-alone": "gatsby develop",
     "serve": "gatsby serve -p 8000",
-    "test": "jest"
+    "test": "jest",
+    "validate-keys": "node ./i18n/validate-keys.js"
   },
   "devDependencies": {
     "@testing-library/jest-dom": "^5.11.9",