Add layout helpers

src/Helpers.php

@@ -41,5 +41,13 @@ class Helpers extends BaseHelpers
         $this->add('uppercase', new String\UppercaseHelper());
         $this->add('repeat', new String\RepeatHelper());
         $this->add('truncate', new String\TruncateHelper());
+
+        // Layout helpers
+        $storage = new Layout\BlockStorage();
+        $this->add('block', new Layout\BlockHelper($storage));
+        $this->add('extends', new Layout\ExtendsHelper($storage));
+        $this->add('override', new Layout\OverrideHelper($storage));
+        $this->add('ifOverridden', new Layout\IfOverriddenHelper($storage));
+        $this->add('unlessOverridden', new Layout\UnlessOverriddenHelper($storage));
     }
 }

src/Layout/AbstractBlockHelper.php

@@ -0,0 +1,34 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Layout;
+
+/**
+ * Contains base functionality for all helpers related with blocks overriding.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+abstract class AbstractBlockHelper
+{
+    /**
+     * @var BlockStorage
+     */
+    protected $blocksStorage;
+
+    /**
+     * Helper's constructor.
+     *
+     * @param BlockStorage $storage A Blocks context instance
+     */
+    public function __construct(BlockStorage $storage)
+    {
+        $this->blocksStorage = $storage;
+    }
+}

src/Layout/BlockHelper.php

@@ -0,0 +1,58 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Layout;
+
+use Handlebars\Context;
+use Handlebars\Helper as HelperInterface;
+use Handlebars\Template;
+
+/**
+ * A helper for defining default content of a block.
+ *
+ * Usage:
+ * ```handlebars
+ *   {{#block name}}
+ *     Default content for the block
+ *   {{/block}}
+ * ```
+ *
+ * Arguments:
+ *  - "name": Name of the block.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class BlockHelper extends AbstractBlockHelper implements HelperInterface
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function execute(Template $template, Context $context, $args, $source)
+    {
+        // Get block name
+        $parsed_args = $template->parseArguments($args);
+        if (count($parsed_args) != 1) {
+            throw new \InvalidArgumentException(
+                '"block" helper expects exactly one argument.'
+            );
+        }
+        $block_name = $context->get(array_shift($parsed_args));
+
+        // If the block is not overridden render and show the default value
+        if (!$this->blocksStorage->has($block_name)) {
+            return $template->render($context);
+        }
+
+        $content = $this->blocksStorage->get($block_name);
+
+        // Show overridden content
+        return $content;
+    }
+}

src/Layout/BlockStorage.php

@@ -0,0 +1,78 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Layout;
+
+/**
+ * A storage for overridable blocks' content.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class BlockStorage
+{
+    /**
+     * Associative array of blocks. The keys are blocks names and the values are
+     * blocks content.
+     *
+     * @type string[]
+     */
+    protected $blocks = array();
+
+    /**
+     * Gets content of a block.
+     *
+     * @param string $name Block's name.
+     * @return string Block's content.
+     */
+    public function get($name)
+    {
+        return isset($this->blocks[$name]) ? $this->blocks[$name] : false;
+    }
+
+    /**
+     * Sets content of a block.
+     *
+     * @param string $name Block's name.
+     * @param string $content Block's content.
+     */
+    public function set($name, $content)
+    {
+        $this->blocks[$name] = $content;
+    }
+
+    /**
+     * Checks if a block exists in the storage.
+     *
+     * @param string $name Block's name
+     * @return boolean
+     */
+    public function has($name)
+    {
+        return isset($this->blocks[$name]);
+    }
+
+    /**
+     * Removes block from the storage.
+     *
+     * @param string $name Block's name.
+     */
+    public function remove($name)
+    {
+        unset($this->blocks[$name]);
+    }
+
+    /**
+     * Removes all blocks from the storage.
+     */
+    public function clear()
+    {
+        $this->blocks = array();
+    }
+}

src/Layout/ExtendsHelper.php

@@ -0,0 +1,79 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Layout;
+
+use Handlebars\Context;
+use Handlebars\Helper as HelperInterface;
+use Handlebars\Template;
+
+/**
+ * A helper for templates extending.
+ *
+ * This helper works as a wrapper for one or more "override" blocks which
+ * defines name of the parent template.
+ *
+ * Example of usage:
+ * ```handlebars
+ *   {{#extends parentTemplateName}}
+ *     {{#override "blockName"}}
+ *       Overridden block content
+ *     {{/override}}
+ *   {{/extends}}
+ * ```
+ *
+ * Arguments:
+ *  - "parentTemplateName": Name of the template that should be extended.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class ExtendsHelper extends AbstractBlockHelper implements HelperInterface
+{
+    /**
+     * The current inheritance level of the templates.
+     * @var int
+     */
+    protected $level = 0;
+
+    /**
+     * {@inheritdoc}
+     */
+    public function execute(Template $template, Context $context, $args, $source)
+    {
+        // Get name of the parent template
+        $parsed_args = $template->parseArguments($args);
+        if (count($parsed_args) != 1) {
+            throw new \InvalidArgumentException(
+                '"extends" helper expects exactly one argument.'
+            );
+        }
+        $parent_template = $context->get(array_shift($parsed_args));
+
+        // Render content inside "extends" block to override blocks
+        $template->render($context);
+
+        // We need another instance of \Handlebars\Template to render parent
+        // template. It can be got from Handlebars engine, so get the engine.
+        $handlebars = $template->getEngine();
+
+        // Render the parent template
+        $this->level++;
+        $buffer = $handlebars->render($parent_template, $context);
+        $this->level--;
+
+        if ($this->level == 0) {
+            // The template and all its parents are rendered. Clean up the
+            // storage.
+            $this->blocksStorage->clear();
+        }
+
+        return $buffer;
+    }
+}

src/Layout/Helpers.php

@@ -0,0 +1,36 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Layout;
+
+use Handlebars\Helpers as BaseHelpers;
+
+/**
+ * Contains all layout helpers.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class Helpers extends BaseHelpers
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected function addDefaultHelpers()
+    {
+        parent::addDefaultHelpers();
+
+        $storage = new BlockStorage();
+        $this->add('block', new BlockHelper($storage));
+        $this->add('extends', new ExtendsHelper($storage));
+        $this->add('override', new OverrideHelper($storage));
+        $this->add('ifOverridden', new IfOverriddenHelper($storage));
+        $this->add('unlessOverridden', new UnlessOverriddenHelper($storage));
+    }
+}

src/Layout/IfOverriddenHelper.php

@@ -0,0 +1,64 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Layout;
+
+use Handlebars\Context;
+use Handlebars\Helper as HelperInterface;
+use Handlebars\Template;
+
+/**
+ * Conditional helper that checks if block overridden or not.
+ *
+ * Usage:
+ * ```handlebars
+ *   {{#ifOverridden name}}
+ *     The block was overridden
+ *   {{else}}
+ *     The block was not overridden
+ *   {{/ifOverridden}}
+ * ```
+ *
+ * Arguments:
+ *  - "name": Name of the block.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class IfOverriddenHelper extends AbstractBlockHelper implements HelperInterface
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function execute(Template $template, Context $context, $args, $source)
+    {
+        // Get block name
+        $parsed_args = $template->parseArguments($args);
+        if (count($parsed_args) != 1) {
+            throw new \InvalidArgumentException(
+                '"ifOverridden" helper expects exactly one argument.'
+            );
+        }
+        $block_name = $context->get(array_shift($parsed_args));
+
+        // Check condition and render blocks
+        if ($this->blocksStorage->has($block_name)) {
+            $template->setStopToken('else');
+            $buffer = $template->render($context);
+            $template->setStopToken(false);
+        } else {
+            $template->setStopToken('else');
+            $template->discard();
+            $template->setStopToken(false);
+            $buffer = $template->render($context);
+        }
+
+        return $buffer;
+    }
+}

src/Layout/OverrideHelper.php

@@ -0,0 +1,59 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Layout;
+
+use Handlebars\Context;
+use Handlebars\Helper as HelperInterface;
+use Handlebars\Template;
+
+/**
+ * A helper for overriding content of a block.
+ *
+ * One or more "override" blocks must be wrapped with
+ * {@link \JustBlackBird\HandlebarsHelpers\Layout\ExtendsHelper} helper.
+ *
+ * Usage:
+ * ```handlebars
+ *   {{#override blockName}}
+ *     Overridden content of the block.
+ *   {{/override}}
+ * ```
+ *
+ * Arguments:
+ *  - blockName: Name of the block which should be overridden.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class OverrideHelper extends AbstractBlockHelper implements HelperInterface
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function execute(Template $template, Context $context, $args, $source)
+    {
+        // Get block name
+        $parsed_args = $template->parseArguments($args);
+        if (count($parsed_args) != 1) {
+            throw new \InvalidArgumentException(
+                '"override" helper expects exactly one argument.'
+            );
+        }
+        $block_name = $context->get(array_shift($parsed_args));
+
+        // We need to provide unlimited inheritence level. Rendering is started
+        // from the deepest level template. If the content is in the block
+        // storage it is related with the deepest level template. Thus we do not
+        // need to override it.
+        if (!$this->blocksStorage->has($block_name)) {
+            $this->blocksStorage->set($block_name, $template->render($context));
+        }
+    }
+}

src/Layout/UnlessOverriddenHelper.php

@@ -0,0 +1,64 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Layout;
+
+use Handlebars\Context;
+use Handlebars\Helper as HelperInterface;
+use Handlebars\Template;
+
+/**
+ * Conditional helper that checks if block overridden or not.
+ *
+ * Usage:
+ * ```handlebars
+ *   {{#unlessOverridden name}}
+ *     The block was not overridden
+ *   {{else}}
+ *     The block was overridden
+ *   {{/unlessOverridden}}
+ * ```
+ *
+ * Arguments:
+ *  - "name": Name of the block.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class UnlessOverriddenHelper extends AbstractBlockHelper implements HelperInterface
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function execute(Template $template, Context $context, $args, $source)
+    {
+        // Get block name
+        $parsed_args = $template->parseArguments($args);
+        if (count($parsed_args) != 1) {
+            throw new \InvalidArgumentException(
+                '"unlessOverridden" helper expects exactly one argument.'
+            );
+        }
+        $block_name = $context->get(array_shift($parsed_args));
+
+        // Check condition and render blocks
+        if (!$this->blocksStorage->has($block_name)) {
+            $template->setStopToken('else');
+            $buffer = $template->render($context);
+            $template->setStopToken(false);
+        } else {
+            $template->setStopToken('else');
+            $template->discard();
+            $template->setStopToken(false);
+            $buffer = $template->render($context);
+        }
+
+        return $buffer;
+    }
+}

tests/HelpersTest.php

@@ -53,6 +53,13 @@ class HelpersTest extends \PHPUnit_Framework_TestCase
             array('uppercase', '\\JustBlackBird\\HandlebarsHelpers\\String\\UppercaseHelper'),
             array('repeat', '\\JustBlackBird\\HandlebarsHelpers\\String\\RepeatHelper'),
             array('truncate', '\\JustBlackBird\\HandlebarsHelpers\\String\\TruncateHelper'),
+
+            // Layout helpers
+            array('block', '\\JustBlackBird\\HandlebarsHelpers\\Layout\\BlockHelper'),
+            array('extends', '\\JustBlackBird\\HandlebarsHelpers\\Layout\\ExtendsHelper'),
+            array('override', '\\JustBlackBird\\HandlebarsHelpers\\Layout\\OverrideHelper'),
+            array('ifOverridden', '\\JustBlackBird\\HandlebarsHelpers\\Layout\\IfOverriddenHelper'),
+            array('unlessOverridden', '\\JustBlackBird\\HandlebarsHelpers\\Layout\\UnlessOverriddenHelper'),
         );
     }
 }

tests/Layout/BlockHelperTest.php

@@ -0,0 +1,50 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Tests\Layout;
+
+use JustBlackBird\HandlebarsHelpers\Layout\BlockHelper;
+use JustBlackBird\HandlebarsHelpers\Layout\BlockStorage;
+
+/**
+ * Test class for "block" helper.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class BlockHelperTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Tests that exception is thrown if wrong number of arguments is used.
+     *
+     * @expectedException InvalidArgumentException
+     * @dataProvider wrongArgumentsProvider
+     */
+    public function testArgumentsCount($template)
+    {
+        $storage = new BlockStorage();
+        $helpers = new \Handlebars\Helpers(array('block' => new BlockHelper($storage)));
+        $engine = new \Handlebars\Handlebars(array('helpers' => $helpers));
+
+        $engine->render($template, array());
+    }
+
+    /**
+     * A data provider for testArgumentsCount method.
+     */
+    public function wrongArgumentsProvider()
+    {
+        return array(
+            // Not enough arguments
+            array('{{#block}}content{{/block}}'),
+            // Too much arguments
+            array('{{#block "arg1" "arg2"}}content{{/block}}'),
+        );
+    }
+}

tests/Layout/BlockStorageTest.php

@@ -0,0 +1,42 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Tests\Layout;
+
+use JustBlackBird\HandlebarsHelpers\Layout\BlockStorage;
+
+/**
+ * Test class for BlockStorage.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class BlockStorageTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Tests basic operations with storage.
+     */
+    public function testBasicOperations()
+    {
+        $storage = new BlockStorage();
+        $this->assertFalse($storage->has('test'));
+        $storage->set('test', 'content');
+        $this->assertTrue($storage->has('test'));
+        $this->assertEquals($storage->get('test'), 'content');
+        $storage->set('test', 'another content');
+        $this->assertEquals($storage->get('test'), 'another content');
+        $storage->remove('test');
+        $this->assertFalse($storage->has('test'));
+        $storage->set('test', 'content');
+        $storage->set('another_test', 'content');
+        $storage->clear();
+        $this->assertFalse($storage->has('test'));
+        $this->assertFalse($storage->has('another_test'));
+    }
+}

tests/Layout/ExtendsHelperTest.php

@@ -0,0 +1,50 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Tests\Layout;
+
+use JustBlackBird\HandlebarsHelpers\Layout\BlockStorage;
+use JustBlackBird\HandlebarsHelpers\Layout\ExtendsHelper;
+
+/**
+ * Test class for "extends" helper.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class ExtendsHelperTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Tests that exception is thrown if wrong number of arguments is used.
+     *
+     * @expectedException InvalidArgumentException
+     * @dataProvider wrongArgumentsProvider
+     */
+    public function testArgumentsCount($template)
+    {
+        $storage = new BlockStorage();
+        $helpers = new \Handlebars\Helpers(array('extends' => new ExtendsHelper($storage)));
+        $engine = new \Handlebars\Handlebars(array('helpers' => $helpers));
+
+        $engine->render($template, array());
+    }
+
+    /**
+     * A data provider for testArgumentsCount method.
+     */
+    public function wrongArgumentsProvider()
+    {
+        return array(
+            // Not enough arguments
+            array('{{#extends}}content{{/extends}}'),
+            // Too much arguments
+            array('{{#extends "arg1" "arg2"}}content{{/extends}}'),
+        );
+    }
+}

tests/Layout/HelpersTest.php

@@ -0,0 +1,48 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Tests\Layout;
+
+use JustBlackBird\HandlebarsHelpers\Layout\Helpers;
+
+/**
+ * Test class for Layout Helpers Set.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class HelpersTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Tests that all helpers in the set exist and have valid classes.
+     *
+     * @dataProvider helpersProvider
+     */
+    public function testHelper($name, $class)
+    {
+        $helpers = new Helpers();
+
+        $this->assertTrue($helpers->has($name), sprintf('There is no "%s" helper', $name));
+        $this->assertInstanceOf($class, $helpers->{$name});
+    }
+
+    /**
+     * A data provider for testHelper method.
+     */
+    public function helpersProvider()
+    {
+        return array(
+            array('block', '\\JustBlackBird\\HandlebarsHelpers\\Layout\\BlockHelper'),
+            array('extends', '\\JustBlackBird\\HandlebarsHelpers\\Layout\\ExtendsHelper'),
+            array('override', '\\JustBlackBird\\HandlebarsHelpers\\Layout\\OverrideHelper'),
+            array('ifOverridden', '\\JustBlackBird\\HandlebarsHelpers\\Layout\\IfOverriddenHelper'),
+            array('unlessOverridden', '\\JustBlackBird\\HandlebarsHelpers\\Layout\\UnlessOverriddenHelper'),
+        );
+    }
+}

tests/Layout/IfOverriddenHelperTest.php

@@ -0,0 +1,50 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Tests\Layout;
+
+use JustBlackBird\HandlebarsHelpers\Layout\BlockStorage;
+use JustBlackBird\HandlebarsHelpers\Layout\IfOverriddenHelper;
+
+/**
+ * Test class for "ifOverridden" helper.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class IfOverriddenHelperTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Tests that exception is thrown if wrong number of arguments is used.
+     *
+     * @expectedException InvalidArgumentException
+     * @dataProvider wrongArgumentsProvider
+     */
+    public function testArgumentsCount($template)
+    {
+        $storage = new BlockStorage();
+        $helpers = new \Handlebars\Helpers(array('ifOverridden' => new IfOverriddenHelper($storage)));
+        $engine = new \Handlebars\Handlebars(array('helpers' => $helpers));
+
+        $engine->render($template, array());
+    }
+
+    /**
+     * A data provider for testArgumentsCount method.
+     */
+    public function wrongArgumentsProvider()
+    {
+        return array(
+            // Not enough arguments
+            array('{{#ifOverridden}}true{{else}}false{{/ifOverridden}}'),
+            // Too much arguments
+            array('{{#ifOverridden "arg1" "arg2"}}true{{else}}false{{/ifOverridden}}'),
+        );
+    }
+}

tests/Layout/IntegrationTest.php

@@ -0,0 +1,98 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Tests\Layout;
+
+use JustBlackBird\HandlebarsHelpers\Layout\BlockHelper;
+use JustBlackBird\HandlebarsHelpers\Layout\BlockStorage;
+use JustBlackBird\HandlebarsHelpers\Layout\ExtendsHelper;
+use JustBlackBird\HandlebarsHelpers\Layout\IfOverriddenHelper;
+use JustBlackBird\HandlebarsHelpers\Layout\OverrideHelper;
+use JustBlackBird\HandlebarsHelpers\Layout\UnlessOverriddenHelper;
+
+/**
+ * Test class for all layout helpers.
+ *
+ * Layout helpers must work together thus combined tests should be used.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class IntegrationTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Tests how inheritance helpers works together.
+     */
+    public function testInheritance()
+    {
+        $storage = new BlockStorage();
+        $helpers = new \Handlebars\Helpers(array(
+            'block' => new BlockHelper($storage),
+            'extends' => new ExtendsHelper($storage),
+            'override' => new OverrideHelper($storage),
+        ));
+        $engine = new \Handlebars\Handlebars(array('helpers' => $helpers));
+
+        // Test simple inheritance
+        $engine->setLoader(new \Handlebars\Loader\ArrayLoader(array(
+            'parent' => '{{#block "name"}}parent{{/block}} template',
+            'child' => '{{#extends "parent"}}{{#override "name"}}child{{/override}}{{/extends}}',
+            'grandchild' => '{{#extends "child"}}{{#override "name"}}grandchild{{/override}}{{/extends}}',
+        )));
+        $this->assertEquals($engine->render('parent', array()), 'parent template');
+        $this->assertEquals($engine->render('child', array()), 'child template');
+        $this->assertEquals($engine->render('grandchild', array()), 'grandchild template');
+
+        // Test inheritance with nested blocks
+        $engine->setLoader(new \Handlebars\Loader\ArrayLoader(array(
+            'parent' => '{{#block "title"}}{{#block "name"}}parent{{/block}} template{{/block}}',
+            'child' => '{{#extends "parent"}}{{#override "name"}}child{{/override}}{{/extends}}',
+            'newbie' => '{{#extends "parent"}}{{#override "title"}}Newbie!{{/override}}{{/extends}}',
+        )));
+        $this->assertEquals($engine->render('parent', array()), 'parent template');
+        $this->assertEquals($engine->render('child', array()), 'child template');
+        $this->assertEquals($engine->render('newbie', array()), 'Newbie!');
+    }
+
+    /**
+     * Tests that conditions related with inheritance works as expected.
+     */
+    public function testConditions()
+    {
+        $storage = new BlockStorage();
+        $helpers = new \Handlebars\Helpers(array(
+            'block' => new BlockHelper($storage),
+            'extends' => new ExtendsHelper($storage),
+            'override' => new OverrideHelper($storage),
+            'ifOverridden' => new IfOverriddenHelper($storage),
+            'unlessOverridden' => new UnlessOverriddenHelper($storage),
+        ));
+        $engine = new \Handlebars\Handlebars(array('helpers' => $helpers));
+
+        // Test "ifOverridden" helper
+        $engine->setLoader(new \Handlebars\Loader\ArrayLoader(array(
+            'parent' => '{{#block "name"}}{{/block}}{{#ifOverridden "name"}}true{{else}}false{{/ifOverridden}}',
+            'child' => '{{#extends "parent"}}{{#override "name"}}{{/override}}{{/extends}}',
+            'another_child' => '{{#extends "parent"}}{{/extends}}',
+        )));
+        $this->assertEquals($engine->render('parent', array()), 'false');
+        $this->assertEquals($engine->render('child', array()), 'true');
+        $this->assertEquals($engine->render('another_child', array()), 'false');
+
+        // Test "unlessOverridden" helper
+        $engine->setLoader(new \Handlebars\Loader\ArrayLoader(array(
+            'parent' => '{{#block "name"}}{{/block}}{{#unlessOverridden "name"}}false{{else}}true{{/unlessOverridden}}',
+            'child' => '{{#extends "parent"}}{{#override "name"}}{{/override}}{{/extends}}',
+            'another_child' => '{{#extends "parent"}}{{/extends}}',
+        )));
+        $this->assertEquals($engine->render('parent', array()), 'false');
+        $this->assertEquals($engine->render('child', array()), 'true');
+        $this->assertEquals($engine->render('another_child', array()), 'false');
+    }
+}

tests/Layout/OverrideHelperTest.php

@@ -0,0 +1,50 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Tests\Layout;
+
+use JustBlackBird\HandlebarsHelpers\Layout\OverrideHelper;
+use JustBlackBird\HandlebarsHelpers\Layout\BlockStorage;
+
+/**
+ * Test class for "override" helper.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class OverrideHelperTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Tests that exception is thrown if wrong number of arguments is used.
+     *
+     * @expectedException InvalidArgumentException
+     * @dataProvider wrongArgumentsProvider
+     */
+    public function testArgumentsCount($template)
+    {
+        $storage = new BlockStorage();
+        $helpers = new \Handlebars\Helpers(array('override' => new OverrideHelper($storage)));
+        $engine = new \Handlebars\Handlebars(array('helpers' => $helpers));
+
+        $engine->render($template, array());
+    }
+
+    /**
+     * A data provider for testArgumentsCount method.
+     */
+    public function wrongArgumentsProvider()
+    {
+        return array(
+            // Not enough arguments
+            array('{{#override}}content{{/override}}'),
+            // Too much arguments
+            array('{{#override "arg1" "arg2"}}content{{/override}}'),
+        );
+    }
+}

tests/Layout/UnlessOverriddenHelperTest.php

@@ -0,0 +1,50 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Tests\Layout;
+
+use JustBlackBird\HandlebarsHelpers\Layout\BlockStorage;
+use JustBlackBird\HandlebarsHelpers\Layout\UnlessOverriddenHelper;
+
+/**
+ * Test class for "unlessOverridden" helper.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class UnlessOverriddenHelperTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Tests that exception is thrown if wrong number of arguments is used.
+     *
+     * @expectedException InvalidArgumentException
+     * @dataProvider wrongArgumentsProvider
+     */
+    public function testArgumentsCount($template)
+    {
+        $storage = new BlockStorage();
+        $helpers = new \Handlebars\Helpers(array('unlessOverridden' => new UnlessOverriddenHelper($storage)));
+        $engine = new \Handlebars\Handlebars(array('helpers' => $helpers));
+
+        $engine->render($template, array());
+    }
+
+    /**
+     * A data provider for testArgumentsCount method.
+     */
+    public function wrongArgumentsProvider()
+    {
+        return array(
+            // Not enough arguments
+            array('{{#unlessOverridden}}false{{else}}true{{/unlessOverridden}}'),
+            // Too much arguments
+            array('{{#unlessOverridden "arg1" "arg2"}}false{{else}}true{{/unlessOverridden}}'),
+        );
+    }
+}