Add Better Auth admin authentication

tests/better-auth-component.test.ts

@@ -0,0 +1,45 @@
+import assert from "node:assert/strict";
+import { readFile } from "node:fs/promises";
+import { join } from "node:path";
+import test from "node:test";
+
+test("local Better Auth component exports adapter functions", async () => {
+  const source = await readFile(
+    join(process.cwd(), "convex/betterAuth/adapter.ts"),
+    "utf8",
+  );
+
+  for (const exportName of [
+    "create",
+    "findOne",
+    "findMany",
+    "updateOne",
+    "updateMany",
+    "deleteOne",
+    "deleteMany",
+  ]) {
+    assert.match(source, new RegExp(`\\b${exportName}\\b`));
+  }
+
+  assert.match(source, /createApi\(schema, createSchemaAuthOptions\)/);
+});
+
+test("Better Auth email/password signup is disabled server-side", async () => {
+  const source = await readFile(
+    join(process.cwd(), "convex/betterAuth/auth.ts"),
+    "utf8",
+  );
+
+  assert.match(source, /disableSignUp:\s*true/);
+});
+
+test("auth entry only exposes sign in", async () => {
+  const source = await readFile(
+    join(process.cwd(), "components/auth-entry.tsx"),
+    "utf8",
+  );
+
+  assert.doesNotMatch(source, /signUp/);
+  assert.doesNotMatch(source, /Account anlegen/);
+  assert.match(source, /authClient\.signIn\.email/);
+});