I18N: Remove the requirement to call load_plugin_textdomain() / load_theme_textdomain().

By initially scanning the `wp-content/languages` directory and loading available MO files just-in-time, plugins and themes do not need to manually load text domains anymore.

Props swissspidy, ocean90.
Fixes #34114

git-svn-id: https://develop.svn.wordpress.org/trunk@37415 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/data/languages/plugins/internationalized-plugin-de_DE.po

@@ -0,0 +1,23 @@
+msgid ""
+msgstr ""
+"Project-Id-Version: \n"
+"POT-Creation-Date: 2015-12-31 16:31+0100\n"
+"PO-Revision-Date: 2016-04-28 18:50+0200\n"
+"Last-Translator: Pascal Birchler <pascal@required.ch>\n"
+"Language-Team: \n"
+"Language: de_DE\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: Poedit 1.8.4\n"
+"X-Poedit-Basepath: .\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+"X-Poedit-KeywordsList: __;_e;_x:1,2c;_ex:1,2c;_n:1,2;_nx:1,2,4c;_n_noop:1,2;"
+"_nx_noop:1,2,3c;esc_attr__;esc_html__;esc_attr_e;esc_html_e;esc_attr_x:1,2c;"
+"esc_html_x:1,2c\n"
+"X-Textdomain-Support: yes\n"
+"X-Poedit-SearchPath-0: .\n"
+
+#: internationalized-plugin.php:11
+msgid "This is a dummy plugin"
+msgstr "Das ist ein Dummy Plugin"

tests/phpunit/data/languages/themes/internationalized-theme-de_DE.po

@@ -0,0 +1,23 @@
+msgid ""
+msgstr ""
+"Project-Id-Version: \n"
+"POT-Creation-Date: 2015-12-31 16:38+0100\n"
+"PO-Revision-Date: 2016-04-28 18:50+0200\n"
+"Last-Translator: Pascal Birchler <pascal@required.ch>\n"
+"Language-Team: \n"
+"Language: de_DE\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: Poedit 1.8.4\n"
+"X-Poedit-Basepath: .\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+"X-Poedit-KeywordsList: __;_e;_x:1,2c;_ex:1,2c;_n:1,2;_nx:1,2,4c;_n_noop:1,2;"
+"_nx_noop:1,2,3c;esc_attr__;esc_html__;esc_attr_e;esc_html_e;esc_attr_x:1,2c;"
+"esc_html_x:1,2c\n"
+"X-Textdomain-Support: yes\n"
+"X-Poedit-SearchPath-0: .\n"
+
+#: functions.php:7
+msgid "This is a dummy theme"
+msgstr "Das ist ein Dummy Theme"

tests/phpunit/data/plugins/internationalized-plugin.php

@@ -0,0 +1,12 @@
+<?php
+/*
+Plugin Name: Dummy Plugin
+Plugin URI: https://wordpress.org/
+Description: For testing purposes only.
+Version: 1.0.0
+Text Domain: internationalized-plugin
+*/
+
+function i18n_plugin_test() {
+	return __( 'This is a dummy plugin', 'internationalized-plugin' );
+}

tests/phpunit/data/themedir1/internationalized-theme/functions.php

@@ -0,0 +1,8 @@
+<?php
+/**
+ * Dummy theme.
+ */
+
+function i18n_theme_test() {
+	return __( 'This is a dummy theme', 'internationalized-theme' );
+}

tests/phpunit/data/themedir1/internationalized-theme/index.php

@@ -0,0 +1,4 @@
+<?php
+/**
+ * Dummy theme.
+ */

tests/phpunit/data/themedir1/internationalized-theme/style.css

@@ -0,0 +1,7 @@
+/*
+Theme Name: Internationalized Theme
+Theme URI: https://wordpress.org/
+Description: For testing purposes only.
+Version: 1.0.0
+Text Domain: internationalized-theme
+*/

tests/phpunit/tests/l10n/loadTextdomainJustInTime.php

@@ -0,0 +1,88 @@
+<?php
+
+/**
+ * @group l10n
+ * @group i18n
+ */
+class Tests_L10n_loadTextdomainJustInTime extends WP_UnitTestCase {
+
+	private $orig_theme_dir;
+	private $theme_root;
+
+	function setUp() {
+		parent::setUp();
+
+		$this->theme_root = DIR_TESTDATA . '/themedir1';
+		$this->orig_theme_dir = $GLOBALS['wp_theme_directories'];
+
+		// /themes is necessary as theme.php functions assume /themes is the root if there is only one root.
+		$GLOBALS['wp_theme_directories'] = array( WP_CONTENT_DIR . '/themes', $this->theme_root );
+		add_filter( 'theme_root', array( $this, 'filter_theme_root' ) );
+		add_filter( 'stylesheet_root', array( $this, 'filter_theme_root' ) );
+		add_filter( 'template_root', array( $this, 'filter_theme_root' ) );
+		wp_clean_themes_cache();
+		unset( $GLOBALS['wp_themes'] );
+	}
+
+	function tearDown() {
+		$GLOBALS['wp_theme_directories'] = $this->orig_theme_dir;
+		remove_filter( 'theme_root', array( $this, 'filter_theme_root' ) );
+		remove_filter( 'stylesheet_root', array( $this, 'filter_theme_root' ) );
+		remove_filter( 'template_root', array( $this, 'filter_theme_root' ) );
+		wp_clean_themes_cache();
+		unset( $GLOBALS['wp_themes'] );
+
+		parent::tearDown();
+	}
+
+	/**
+	 * Replace the normal theme root dir with our pre-made test dir.
+	 */
+	public function filter_theme_root() {
+		return $this->theme_root;
+	}
+
+	public function filter_set_locale_to_german() {
+		return 'de_DE';
+	}
+
+	/**
+	 * @ticket 34114
+	 */
+	public function test_plugin_translation_should_be_translated_without_calling_load_plugin_textdomain() {
+		add_filter( 'locale', array( $this, 'filter_set_locale_to_german' ) );
+
+		require_once DIR_TESTDATA . '/plugins/internationalized-plugin.php';
+
+		$is_textdomain_loaded_before = is_textdomain_loaded( 'internationalized-plugin' );
+		$expected_output             = i18n_plugin_test();
+		$is_textdomain_loaded_after  = is_textdomain_loaded( 'internationalized-plugin' );
+
+		remove_filter( 'locale', array( $this, 'filter_set_locale_to_german' ) );
+
+		$this->assertFalse( $is_textdomain_loaded_before );
+		$this->assertSame( 'Das ist ein Dummy Plugin', $expected_output );
+		$this->assertTrue( $is_textdomain_loaded_after );
+	}
+
+	/**
+	 * @ticket 34114
+	 */
+	public function test_theme_translation_should_be_translated_without_calling_load_theme_textdomain() {
+		add_filter( 'locale', array( $this, 'filter_set_locale_to_german' ) );
+
+		switch_theme( 'internationalized-theme' );
+
+		include_once get_stylesheet_directory() . '/functions.php';
+
+		$is_textdomain_loaded_before = is_textdomain_loaded( 'internationalized-theme' );
+		$expected_output             = i18n_theme_test();
+		$is_textdomain_loaded_after  = is_textdomain_loaded( 'internationalized-theme' );
+
+		remove_filter( 'locale', array( $this, 'filter_set_locale_to_german' ) );
+
+		$this->assertFalse( $is_textdomain_loaded_before );
+		$this->assertSame( 'Das ist ein Dummy Theme', $expected_output );
+		$this->assertTrue( $is_textdomain_loaded_after );
+	}
+}

tests/phpunit/tests/theme/themeDir.php

@@ -159,6 +159,7 @@ class Tests_Theme_ThemeDir extends WP_UnitTestCase {
 			'My Subdir Theme',// theme in a subdirectory should work
 			'Page Template Theme', // theme with page templates for other test code
 			'Theme with Spaces in the Directory',
+			'Internationalized Theme',
 		);
 
 		sort($theme_names);