MDTT-12: Support custom transformation plugins (#13)

README.md

@@ -15,8 +15,11 @@ composer require --dev axelerant/mdtt
 Basically you follow these steps:
 
 1. Specify test specifications
-1. Specify test definitions
-1. Run the tests
+2. Specify test definitions
+3. _Optionally_, specify transform plugins
+4. Run the tests
+
+You can find the basic template for the tool usage [here](https://github.com/axelerant/mdtt-usage).
 
 ### Test specification
 
@@ -113,7 +116,51 @@ tests:
     destinationField: email
 ```
 
-You can find the basic template for the tool usage [here](https://github.com/axelerant/mdtt-usage).
+### Transform plugin
+
+There could be a scenario where instead of directly storing the data from source, it must be transformed in some way (say, whitespaces must be stripped) before storing it in the destination database. A QA engineer can write their own plugin, to validate the business logic that does the transformation.
+
+The test case would look like this:
+
+```yaml
+tests:
+  -
+    sourceField: name
+    transform: trim
+    destinationField: name
+```
+
+The QA engineer must specify the plugin class inside `tests/mdtt/src/Plugin/Transform`. The file name (and, class name) must be same as the plugin name mentioned in the test case with the first character in upper case, i.e. `Trim`. The plugin class must implement `\Mdtt\Transform\Transform` interface.
+
+```php
+<?php
+
+// File location: tests/mdtt/src/Plugin/Transform/Trim.php.
+
+class Trim implements \Mdtt\Transform\Transform
+{
+    /**
+     * @inheritDoc
+     */
+    public function name(): string
+    {
+        // Specifies the plugin name.
+        // This must be unique, if you have multiple plugin definitions.
+        // The same plugin name must be mentioned in the test case.
+        return "trim";
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function process(mixed $data): mixed
+    {
+        // The logic that does the transformation.
+        return trim($data);
+    }
+}
+
+```
 
 ## Run tests
 

config/services.yml

@@ -20,6 +20,11 @@ services:
 
   Psr\Log\LoggerInterface: '@logger'
 
+  transform_plugin_manager:
+    class: \Mdtt\Transform\DefaultPluginManager
+
+  Mdtt\Transform\PluginManager: '@transform_plugin_manager'
+
   Mdtt\:
     lazy: true
     resource: '../src/*'

src/LoadDefinition/DefaultLoader.php

@@ -8,6 +8,8 @@
 use Mdtt\Definition\Validate\DataSource\Validator;
 use Mdtt\Exception\SetupException;
 use Mdtt\Test\DefaultTest;
+use Mdtt\Transform\PluginManager;
+use Mdtt\Transform\Transform;
 use Psr\Log\LoggerInterface;
 use Symfony\Component\Filesystem\Exception\IOException;
 use Symfony\Component\Yaml\Yaml;
@@ -16,11 +18,17 @@ class DefaultLoader implements Load
 {
     private LoggerInterface $logger;
     private Validator $dataSourceValidator;
+    private PluginManager $transformPluginManager;
+    /**
+     * @var array<string, Transform>
+     */
+    private array $transformPlugins;
 
-    public function __construct(LoggerInterface $logger, Validator $validator)
+    public function __construct(LoggerInterface $logger, Validator $validator, PluginManager $transformPluginManager)
     {
         $this->logger = $logger;
         $this->dataSourceValidator = $validator;
+        $this->transformPluginManager = $transformPluginManager;
     }
 
     /**
@@ -93,8 +101,24 @@ public function validate(): iterable
                 $sourceField = $test['sourceField'];
                 /** @var string $destinationField */
                 $destinationField = $test['destinationField'];
-
-                $parsedTests[] = new DefaultTest($sourceField, $destinationField, $this->logger);
+                $testInstance = new DefaultTest(
+                    $sourceField,
+                    $destinationField,
+                    $this->logger
+                );
+
+                if (isset($test['transform'])) {
+                    if (!isset($this->transformPlugins[$test['transform']])) {
+                        $transformPlugin = $this->transformPluginManager->loadById($test['transform']);
+                        $this->transformPlugins[$transformPlugin->name()] = $transformPlugin;
+                    } else {
+                        $transformPlugin = $this->transformPlugins[$test['transform']];
+                    }
+
+                    $testInstance->setTransform($transformPlugin);
+                }
+
+                $parsedTests[] = $testInstance;
             }
             $parsedTestDefinition->setTests($parsedTests);
 

src/Test/DefaultTest.php

@@ -29,9 +29,22 @@ public function execute(array $sourceData, array $destinationData): void
             $destinationData[$this->getDestinationField()]
         ));
 
+        /** @var string|int $sourceValue */
+        $sourceValue = $sourceData[$this->getSourceField()];
+        if ($this->getTransform() !== null) {
+            $sourceValue = $this->getTransform()->process($sourceValue);
+
+            $this->getLogger()->notice(sprintf(
+                "Applied transform: %s on source. Comparing source %s with destination %s",
+                $this->getTransform()->name(),
+                $sourceValue,
+                $destinationData[$this->getDestinationField()]
+            ));
+        }
+
         try {
             Assert::assertSame(
-                $sourceData[$this->getSourceField()],
+                $sourceValue,
                 $destinationData[$this->getDestinationField()],
                 "Source and destination does not match."
             );

src/Test/Test.php

@@ -4,13 +4,15 @@
 
 namespace Mdtt\Test;
 
+use Mdtt\Transform\Transform;
 use Psr\Log\LoggerInterface;
 
 abstract class Test
 {
     private string $sourceField;
     private string $destinationField;
     private LoggerInterface $logger;
+    private ?Transform $transform;
 
     /**
      * @return \Psr\Log\LoggerInterface
@@ -24,12 +26,18 @@ public function getLogger(): LoggerInterface
      * @param string $sourceField
      * @param string $destinationField
      * @param \Psr\Log\LoggerInterface $logger
+     * @param \Mdtt\Transform\Transform|null $transform
      */
-    public function __construct(string $sourceField, string $destinationField, LoggerInterface $logger)
-    {
+    public function __construct(
+        string $sourceField,
+        string $destinationField,
+        LoggerInterface $logger,
+        Transform $transform = null
+    ) {
         $this->sourceField = $sourceField;
         $this->destinationField = $destinationField;
         $this->logger = $logger;
+        $this->transform = $transform;
     }
 
     /**
@@ -48,6 +56,22 @@ public function getDestinationField(): string
         return $this->destinationField;
     }
 
+    /**
+     * @return \Mdtt\Transform\Transform|null
+     */
+    public function getTransform(): ?Transform
+    {
+        return $this->transform;
+    }
+
+    /**
+     * @param \Mdtt\Transform\Transform $transform
+     */
+    public function setTransform(Transform $transform): void
+    {
+        $this->transform = $transform;
+    }
+
     /**
      * Compare the source and the destination data.
      *

src/Transform/DefaultPluginManager.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Mdtt\Transform;
+
+class DefaultPluginManager implements PluginManager
+{
+    /**
+     * @inheritDoc
+     */
+    public function loadById(string $id): Transform
+    {
+        $pluginId = ucwords($id);
+
+        require "tests/mdtt/src/Plugin/Transform/$pluginId.php";
+
+        /** @var \Mdtt\Transform\Transform $pluginInstance */
+        $pluginInstance = new $pluginId();
+        return $pluginInstance;
+    }
+}

src/Transform/PluginManager.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace Mdtt\Transform;
+
+interface PluginManager
+{
+    /**
+     * Scans all transform plugins and instantiates them.
+     *
+     * @param string $id
+     *
+     * @return \Mdtt\Transform\Transform
+     */
+    public function loadById(string $id): Transform;
+}

src/Transform/Transform.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Mdtt\Transform;
+
+interface Transform
+{
+    /**
+     * Name of the plugin.
+     *
+     * @return string
+     */
+    public function name(): string;
+
+    /**
+     * Alters the provided data.
+     *
+     * @param string|int $data
+     *
+     * @return string|int
+     */
+    public function process(mixed $data): mixed;
+}