Add spec for updating meta document

tests/chat-messages-spec.js

@@ -1,5 +1,5 @@
 const expect = require('chai').expect;
-const sinon = require("sinon");
+const sandbox = require("sinon").createSandbox();
 const ChatMessages = require('../dist/build');
 
 const rsClient = {
@@ -64,6 +64,46 @@ describe('ChatMessages', function () {
         expect(archive.next).to.be.an('undefined');
       });
     });
+
+    describe('#_updateArchiveMetaDocument', function () {
+      describe('meta up to date', function () {
+        before(function() {
+          sandbox.stub(archive.client, 'getObject').withArgs(archive.metaPath)
+                 .returns({
+                   '@id': `chat-messages/irc.libera.chat/channels/kosmos/meta`,
+                   '@type': 'ChatChannelMeta',
+                   first: '2021/01/01', last: '2022/08/11'
+                 })
+          sandbox.stub(archive.client, 'storeObject');
+        });
+
+        it('does not store a new archive', async function () {
+          await archive._updateArchiveMetaDocument();
+          sandbox.assert.notCalled(archive.client.storeObject);
+        });
+
+        after(function() { sandbox.restore() });
+      });
+
+      describe('meta needs updating', function () {
+        before(function() {
+          sandbox.stub(archive.client, 'getObject').withArgs(archive.metaPath)
+                 .returns({
+                   '@id': `chat-messages/irc.libera.chat/channels/kosmos/meta`,
+                   '@type': 'ChatChannelMeta',
+                   first: '2021/01/01', last: '2022/08/10'
+                 })
+          sandbox.stub(archive.client, 'storeObject');
+        });
+
+        it('stores a new archive', async function () {
+          await archive._updateArchiveMetaDocument();
+          sandbox.assert.calledOnce(archive.client.storeObject);
+        });
+
+        after(function() { sandbox.restore() });
+      });
+    });
   });
 
 });