Fix chain file regex and add tests

.changeset/eight-apples-suffer.md

@@ -0,0 +1,5 @@
+---
+'@hyperlane-xyz/registry': patch
+---
+
+Fix chain file regex and add tests

src/registry/BaseRegistry.ts

@@ -4,7 +4,7 @@ import type { ChainMap, ChainMetadata, ChainName } from '@hyperlane-xyz/sdk';
 import type { ChainAddresses, MaybePromise } from '../types.js';
 import type { IRegistry, RegistryContent, RegistryType } from './IRegistry.js';
 
-export const CHAIN_FILE_REGEX = /chains\/([a-z]+)\/([a-z0-9]+)\.yaml/;
+export const CHAIN_FILE_REGEX = /chains\/([a-z0-9]+)\/([a-z]+)\.yaml/;
 
 export abstract class BaseRegistry implements IRegistry {
   abstract type: RegistryType;

test/unit/registry.test.ts

@@ -1,6 +1,7 @@
 import { expect } from 'chai';
 
 import type { ChainMetadata } from '@hyperlane-xyz/sdk';
+import { CHAIN_FILE_REGEX } from '../../src/registry/BaseRegistry.js';
 import { GithubRegistry } from '../../src/registry/GithubRegistry.js';
 import { LocalRegistry } from '../../src/registry/LocalRegistry.js';
 import { ChainAddresses } from '../../src/types.js';
@@ -76,3 +77,11 @@ describe('Registry utilities', () => {
     }).timeout(5_000);
   }
 });
+
+describe('Registry regex', () => {
+  it('Matches chain file regex', () => {
+    expect(CHAIN_FILE_REGEX.test('chains/ethereum/metadata.yaml')).to.be.true;
+    expect(CHAIN_FILE_REGEX.test('chains/ancient8/addresses.yaml')).to.be.true;
+    expect(CHAIN_FILE_REGEX.test('chains/_NotAChain/addresses.yaml')).to.be.false;
+  });
+});