Add Log client for integration testing (#24)

Author: spawnia

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+## v0.6.0
+
+### Added
+
+- Add `Log` client for integration testing https://github.com/spawnia/sailor/pull/24
+
 ## v0.5.0
 
 ### Changed

README.md

@@ -213,6 +213,31 @@ $mock2 = HelloSailor::mock();
 assert($mock1 === $mock2); // true
 ```
 
+### Integration
+
+If you want to perform integration testing for a service that uses Sailor without actually
+hitting an external API, you can swap out your client with the `Log` client.
+It writes all requests made through Sailor to a file of your choice.
+
+```php
+# sailor.php
+public function makeClient(): Client
+{
+    return new \Spawnia\Sailor\Client\Log(__DIR__ . '/sailor-requests.log');
+}
+```
+
+Each request goes on a new line and contains a JSON string that holds the `query` and `variables`:
+
+```json
+{"query":"{ foo }","variables":{"bar":42}}
+{"query":"mutation { baz }","variables":null}
+```
+
+This allows you to perform assertions on the calls that were made.
+However, the `Log` client can not know what constitutes a valid response for a given response,
+so it always responds with an error.
+
 ## Examples
 
 You can find examples of how a project would use Sailor within [examples](examples).

src/Client/Log.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Spawnia\Sailor\Client;
+
+use Spawnia\Sailor\Client;
+use Spawnia\Sailor\Response;
+
+class Log implements Client
+{
+    public const ERROR_MESSAGE = 'Request went to the Log client. It is only meant for testing and can not produce valid responses.';
+
+    protected string $filename;
+
+    public function __construct(string $filename)
+    {
+        $this->filename = $filename;
+    }
+
+    public function request(string $query, \stdClass $variables = null): Response
+    {
+        $log = \Safe\json_encode([
+            'query' => $query,
+            'variables' => $variables,
+        ]);
+
+        $file = \Safe\fopen($this->filename, 'a');
+        \Safe\fwrite($file, "{$log}\n");
+        \Safe\fclose($file);
+
+        return Response::fromStdClass((object) [
+            'errors' => [
+                (object) [
+                    'message' => self::ERROR_MESSAGE,
+                ],
+            ],
+        ]);
+    }
+}

src/Operation.php

@@ -22,7 +22,7 @@ abstract class Operation
      *
      * @var array<class-string<static>, static&MockInterface>
      */
-    private static array $mocks = [];
+    protected static array $mocks = [];
 
     /**
      * The configured endpoint the operation belongs to.

tests/Unit/Client/LogTest.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Spawnia\Sailor\Tests\Unit\Client;
+
+use PHPUnit\Framework\TestCase;
+use Spawnia\Sailor\Client\Log;
+
+class LogTest extends TestCase
+{
+    const FILENAME = __DIR__.'/LogTest.log';
+    const EXPECTED_JSON = /** @lang JSON */ '{"query":"{ foo }","variables":{"bar":42}}'."\n";
+
+    protected function tearDown(): void
+    {
+        if (file_exists(self::FILENAME)) {
+            \Safe\unlink(self::FILENAME);
+        }
+
+        parent::tearDown();
+    }
+
+    public function testRequest(): void
+    {
+        self::assertFileDoesNotExist(self::FILENAME);
+
+        $log = new Log(self::FILENAME);
+        $log->request(/** @lang GraphQL */ '{ foo }', (object) ['bar' => 42]);
+
+        $contents = \Safe\file_get_contents(self::FILENAME);
+        self::assertSame(self::EXPECTED_JSON, $contents);
+
+        $log->request(/** @lang GraphQL */ '{ foo }', (object) ['bar' => 42]);
+
+        $contents = \Safe\file_get_contents(self::FILENAME);
+        self::assertSame(self::EXPECTED_JSON.self::EXPECTED_JSON, $contents);
+    }
+}