add special tests + remove n.is-a.dev as dupe single letter

domains/_vercel.n.json

@@ -1,9 +0,0 @@
-{
-  "owner": {
-    "username": "syedtahseen",
-    "email": "itxtahseen@gmail.com"
-  },
-  "record": {
-    "TXT": ["vc-domain-verify=n.is-a.dev,8435c76be2d4e8aaa229"]
-  }
-}

domains/n.json

@@ -1,9 +0,0 @@
-{
-  "owner": {
-    "username": "syedtahseen",
-    "email": "itxtahseen@gmail.com"
-  },
-  "record": {
-    "CNAME": "xproject-xi.vercel.app"
-  }
-}

tests/domains.test.js

@@ -3,7 +3,7 @@ const fs = require("fs-extra");
 const path = require("path");
 
 const domainsPath = path.resolve("domains");
-const files = fs.readdirSync(domainsPath);
+const files = fs.readdirSync(domainsPath).filter((file) => file.endsWith(".json"));
 
 const domainCache = {};
 

tests/special.test.js

@@ -0,0 +1,49 @@
+const t = require("ava");
+const fs = require("fs-extra");
+const path = require("path");
+
+const domainsPath = path.resolve("domains");
+const files = fs.readdirSync(domainsPath).filter((file) => file.endsWith(".json"));
+
+const bypassedUsernames = require("../util/bypassed-usernames.json").map((username) => username.toLowerCase());
+
+function getDomainData(subdomain) {
+    try {
+        const data = fs.readJsonSync(path.join(domainsPath, `${subdomain}.json`));
+        return data;
+    } catch (error) {
+        throw new Error(`Failed to read JSON for ${subdomain}: ${error.message}`);
+    }
+}
+
+t("Users are limited to one single character subdomain", (t) => {
+    const results = [];
+
+    files.forEach((file) => {
+        const subdomain = file.replace(/\.json$/, "");
+        const data = getDomainData(subdomain);
+
+        if (subdomain.length === 1 && !bypassedUsernames.includes(data.owner.username.toLowerCase())) {
+            results.push({
+                subdomain,
+                owner: data.owner.username.toLowerCase(),
+            })
+        }
+    });
+
+    const duplicates = results.filter((result) => results.filter((r) => r.owner === result.owner).length > 1);
+
+    // Combine duplicates into multiple strings, only one per user, with list of their domains
+    const output = duplicates.reduce((acc, curr) => {
+        if (!acc[curr.owner]) {
+            acc[curr.owner] = [];
+        }
+
+        acc[curr.owner].push(`${curr.subdomain}.is-a.dev`);
+        return acc;
+    }, {});
+
+    t.is(duplicates.length, 0, Object.keys(output).map((owner) => `${owner} - ${output[owner].join(", ")}`).join("\n"));
+
+    t.pass();
+})