minor #204 [Agent] Add unit tests for Chat (OskarStark)

This PR was squashed before being merged into the main branch.

Discussion
----------

[Agent] Add unit tests for `Chat`

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| Docs?         | no
| Issues        | --
| License       | MIT

Commits
-------

64b9dfc [Agent] Add unit tests for `Chat`

Author: OskarStark

src/agent/tests/ChatTest.php

@@ -0,0 +1,173 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\AI\Agent\Tests;
+
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\Small;
+use PHPUnit\Framework\Attributes\Test;
+use PHPUnit\Framework\Attributes\UsesClass;
+use PHPUnit\Framework\TestCase;
+use Symfony\AI\Agent\AgentInterface;
+use Symfony\AI\Agent\Chat;
+use Symfony\AI\Agent\Chat\MessageStoreInterface;
+use Symfony\AI\Platform\Message\AssistantMessage;
+use Symfony\AI\Platform\Message\Message;
+use Symfony\AI\Platform\Message\MessageBag;
+use Symfony\AI\Platform\Message\MessageBagInterface;
+use Symfony\AI\Platform\Result\TextResult;
+
+#[CoversClass(Chat::class)]
+#[UsesClass(Message::class)]
+#[UsesClass(MessageBag::class)]
+#[UsesClass(TextResult::class)]
+#[Small]
+final class ChatTest extends TestCase
+{
+    private AgentInterface&\PHPUnit\Framework\MockObject\MockObject $agent;
+    private MessageStoreInterface&\PHPUnit\Framework\MockObject\MockObject $store;
+    private Chat $chat;
+
+    protected function setUp(): void
+    {
+        $this->agent = $this->createMock(AgentInterface::class);
+        $this->store = $this->createMock(MessageStoreInterface::class);
+        $this->chat = new Chat($this->agent, $this->store);
+    }
+
+    #[Test]
+    public function itInitiatesChatByClearingAndSavingMessages(): void
+    {
+        $messages = $this->createMock(MessageBagInterface::class);
+
+        $this->store->expects($this->once())
+            ->method('clear');
+
+        $this->store->expects($this->once())
+            ->method('save')
+            ->with($messages);
+
+        $this->chat->initiate($messages);
+    }
+
+    #[Test]
+    public function itSubmitsUserMessageAndReturnsAssistantMessage(): void
+    {
+        $userMessage = Message::ofUser('Hello, how are you?');
+        $existingMessages = new MessageBag();
+        $assistantContent = 'I am doing well, thank you!';
+
+        $textResult = new TextResult($assistantContent);
+
+        $this->store->expects($this->once())
+            ->method('load')
+            ->willReturn($existingMessages);
+
+        $this->agent->expects($this->once())
+            ->method('call')
+            ->with($this->callback(function (MessageBagInterface $messages) use ($userMessage) {
+                $messagesArray = $messages->getMessages();
+
+                return end($messagesArray) === $userMessage;
+            }))
+            ->willReturn($textResult);
+
+        $this->store->expects($this->once())
+            ->method('save')
+            ->with($this->callback(function (MessageBagInterface $messages) use ($userMessage, $assistantContent) {
+                $messagesArray = $messages->getMessages();
+                $lastTwo = \array_slice($messagesArray, -2);
+
+                return 2 === \count($lastTwo)
+                    && $lastTwo[0] === $userMessage
+                    && $lastTwo[1] instanceof AssistantMessage
+                    && $lastTwo[1]->content === $assistantContent;
+            }));
+
+        $result = $this->chat->submit($userMessage);
+
+        $this->assertInstanceOf(AssistantMessage::class, $result);
+        $this->assertSame($assistantContent, $result->content);
+    }
+
+    #[Test]
+    public function itAppendsMessagesToExistingConversation(): void
+    {
+        $existingUserMessage = Message::ofUser('What is the weather?');
+        $existingAssistantMessage = Message::ofAssistant('I cannot provide weather information.');
+
+        $existingMessages = new MessageBag();
+        $existingMessages->add($existingUserMessage);
+        $existingMessages->add($existingAssistantMessage);
+
+        $newUserMessage = Message::ofUser('Can you help with programming?');
+        $newAssistantContent = 'Yes, I can help with programming!';
+
+        $textResult = new TextResult($newAssistantContent);
+
+        $this->store->expects($this->once())
+            ->method('load')
+            ->willReturn($existingMessages);
+
+        $this->agent->expects($this->once())
+            ->method('call')
+            ->with($this->callback(function (MessageBagInterface $messages) {
+                $messagesArray = $messages->getMessages();
+
+                return 3 === \count($messagesArray);
+            }))
+            ->willReturn($textResult);
+
+        $this->store->expects($this->once())
+            ->method('save')
+            ->with($this->callback(function (MessageBagInterface $messages) {
+                $messagesArray = $messages->getMessages();
+
+                return 4 === \count($messagesArray);
+            }));
+
+        $result = $this->chat->submit($newUserMessage);
+
+        $this->assertInstanceOf(AssistantMessage::class, $result);
+        $this->assertSame($newAssistantContent, $result->content);
+    }
+
+    #[Test]
+    public function itHandlesEmptyMessageStore(): void
+    {
+        $userMessage = Message::ofUser('First message');
+        $emptyMessages = new MessageBag();
+        $assistantContent = 'First response';
+
+        $textResult = new TextResult($assistantContent);
+
+        $this->store->expects($this->once())
+            ->method('load')
+            ->willReturn($emptyMessages);
+
+        $this->agent->expects($this->once())
+            ->method('call')
+            ->with($this->callback(function (MessageBagInterface $messages) {
+                $messagesArray = $messages->getMessages();
+
+                return 1 === \count($messagesArray);
+            }))
+            ->willReturn($textResult);
+
+        $this->store->expects($this->once())
+            ->method('save');
+
+        $result = $this->chat->submit($userMessage);
+
+        $this->assertInstanceOf(AssistantMessage::class, $result);
+        $this->assertSame($assistantContent, $result->content);
+    }
+}