diff --git a/.gitignore b/.gitignore
index 78066f63..1344a0b0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -42,6 +42,11 @@ npm-debug.log
 
 # Composer (si hay dependencias PHP)
 vendor/
+composer.lock
+
+# PHPUnit
+.phpunit.result.cache
+/tests/_output/
 
 # Environment files
 .env
diff --git a/composer.json b/composer.json
new file mode 100644
index 00000000..1dacfa5a
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,39 @@
+{
+    "name": "roi/roi-theme",
+    "description": "ROI Theme - Migración a Clean Architecture + POO",
+    "type": "wordpress-theme",
+    "license": "proprietary",
+    "require": {
+        "php": ">=8.0"
+    },
+    "require-dev": {
+        "phpunit/phpunit": "^9.0",
+        "squizlabs/php_codesniffer": "^3.7",
+        "wp-coding-standards/wpcs": "^3.0",
+        "mockery/mockery": "^1.5"
+    },
+    "autoload": {
+        "psr-4": {
+            "ROITheme\\": "src/"
+        }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "ROITheme\\Tests\\": "tests/"
+        }
+    },
+    "scripts": {
+        "test": "phpunit",
+        "phpcs": "phpcs --standard=WordPress src/",
+        "phpcbf": "phpcbf --standard=WordPress src/"
+    },
+    "config": {
+        "secure-http": true,
+        "disable-tls": false,
+        "preferred-install": "dist",
+        "platform-check": false,
+        "allow-plugins": {
+            "dealerdirect/phpcodesniffer-composer-installer": true
+        }
+    }
+}
diff --git a/phpcs.xml b/phpcs.xml
new file mode 100644
index 00000000..429ccdca
--- /dev/null
+++ b/phpcs.xml
@@ -0,0 +1,30 @@
+<?xml version="1.0"?>
+<ruleset name="ROI Theme Coding Standards">
+    <description>Estándares de código para ROI Theme</description>
+
+    <!-- Paths a analizar -->
+    <file>src</file>
+
+    <!-- Paths a excluir -->
+    <exclude-pattern>*/vendor/*</exclude-pattern>
+    <exclude-pattern>*/tests/*</exclude-pattern>
+    <exclude-pattern>*/admin/*</exclude-pattern><!-- Legacy code -->
+
+    <!-- Usar estándar WordPress -->
+    <rule ref="WordPress">
+        <!-- Excluir reglas que no aplican para código nuevo -->
+        <exclude name="WordPress.Files.FileName.InvalidClassFileName"/>
+        <exclude name="WordPress.Files.FileName.NotHyphenatedLowercase"/>
+    </rule>
+
+    <!-- Configuraciones adicionales -->
+    <arg name="colors"/>
+    <arg name="extensions" value="php"/>
+    <arg name="parallel" value="8"/>
+
+    <!-- Mostrar progreso -->
+    <arg value="sp"/>
+
+    <!-- PHP 8.0+ -->
+    <config name="testVersion" value="8.0-"/>
+</ruleset>
diff --git a/phpunit.xml b/phpunit.xml
new file mode 100644
index 00000000..8aaf2c2d
--- /dev/null
+++ b/phpunit.xml
@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.5/phpunit.xsd"
+    bootstrap="tests/_bootstrap/bootstrap.php"
+    colors="true"
+    verbose="true"
+    stopOnFailure="false"
+    beStrictAboutOutputDuringTests="true"
+    beStrictAboutTestsThatDoNotTestAnything="true">
+
+    <testsuites>
+        <testsuite name="Unit">
+            <directory>tests/Unit</directory>
+        </testsuite>
+        <testsuite name="Integration">
+            <directory>tests/Integration</directory>
+        </testsuite>
+        <testsuite name="E2E">
+            <directory>tests/E2E</directory>
+        </testsuite>
+    </testsuites>
+
+    <coverage processUncoveredFiles="true">
+        <include>
+            <directory suffix=".php">src</directory>
+        </include>
+        <exclude>
+            <directory>src/Infrastructure/UI/Views</directory>
+        </exclude>
+    </coverage>
+
+    <php>
+        <env name="APP_ENV" value="testing"/>
+    </php>
+</phpunit>
diff --git a/tests/Unit/ExampleTest.php b/tests/Unit/ExampleTest.php
new file mode 100644
index 00000000..dd5fb5ce
--- /dev/null
+++ b/tests/Unit/ExampleTest.php
@@ -0,0 +1,30 @@
+<?php
+
+namespace ROITheme\Tests\Unit;
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Test de ejemplo para verificar que PHPUnit funciona
+ */
+class ExampleTest extends TestCase
+{
+    public function testPhpUnitIsWorking(): void
+    {
+        $this->assertTrue(true, 'PHPUnit está funcionando correctamente');
+    }
+
+    public function testPhpVersion(): void
+    {
+        $version = PHP_VERSION;
+        $this->assertGreaterThanOrEqual('8.0.0', $version, 'PHP debe ser versión 8.0 o superior');
+    }
+
+    public function testComposerAutoloadIsLoaded(): void
+    {
+        $this->assertTrue(
+            class_exists('PHPUnit\Framework\TestCase'),
+            'Composer autoload está funcionando'
+        );
+    }
+}
diff --git a/tests/_bootstrap/bootstrap.php b/tests/_bootstrap/bootstrap.php
new file mode 100644
index 00000000..5deafdc4
--- /dev/null
+++ b/tests/_bootstrap/bootstrap.php
@@ -0,0 +1,21 @@
+<?php
+/**
+ * PHPUnit Bootstrap
+ *
+ * Se ejecuta antes de todos los tests
+ */
+
+// Cargar autoloader de Composer
+require_once dirname(__DIR__, 2) . '/vendor/autoload.php';
+
+// Definir constantes de WordPress si no existen (para tests unitarios puros)
+if (!defined('ABSPATH')) {
+    define('ABSPATH', dirname(__DIR__, 5) . '/');
+}
+
+if (!defined('WP_DEBUG')) {
+    define('WP_DEBUG', true);
+}
+
+// Para tests de integración, se cargará WordPress completo
+// Esto se hará en un bootstrap separado para tests de integración