diff --git a/tools/i18n/t/AddTextdomainTest.php b/tools/i18n/t/AddTextdomainTest.php
new file mode 100755
index 0000000000..1c991dd363
--- /dev/null
+++ b/tools/i18n/t/AddTextdomainTest.php
@@ -0,0 +1,24 @@
+<?php
+/**
+ * Tests for add-textdomain.php
+ *
+ * @package wordpress-i18n
+ * @subpackage tools
+ */
+error_reporting( E_ALL );
+require_once dirname( dirname( __FILE__ ) ) . '/add-textdomain.php';
+
+class AddTextDomainTest extends PHPUnit_Framework_TestCase {
+
+	function __construct() {
+		$this->atd = new AddTextdomain;
+	}
+
+	function test_add() {
+		# copy to a new file, so that we don't corrupt the old one
+		copy( 'data/add-textdomain-0.php', 'data/add-textdomain-0-work.php' );
+		$this->atd->process_file( 'test-domain', 'data/add-textdomain-0-work.php', true );
+		$this->assertEquals( file_get_contents( 'data/add-textdomain-0-result.php' ), file_get_contents( 'data/add-textdomain-0-work.php' ) );
+		unlink( 'data/add-textdomain-0-work.php' );
+	}
+}
diff --git a/tools/i18n/t/data/add-textdomain-0-result.php b/tools/i18n/t/data/add-textdomain-0-result.php
new file mode 100755
index 0000000000..4c20cb890e
--- /dev/null
+++ b/tools/i18n/t/data/add-textdomain-0-result.php
@@ -0,0 +1,17 @@
+<?php
+function call_some_i18n_methods() {
+	__( 'Hello World' , 'test-domain');
+	_e( 'Hello World' , 'test-domain');
+	_n( 'Single', 'Plural', 1 , 'test-domain');
+	_n_noop( 'Single Noop', 'Plural Noop', 1 , 'test-domain');
+	_x( 'Hello World', 'Testing' , 'test-domain');
+	_ex( 'Hello World', 'Testing' , 'test-domain');
+	_nx( 'Hello World', 'Testing' , 'test-domain');
+	_nx_noop( 'Hello World Noop', 'Testing' , 'test-domain');
+	esc_attr__( 'Attribute' , 'test-domain');
+	esc_html__( 'HTML' , 'test-domain');
+	esc_attr_e( 'Attribute' , 'test-domain');
+	esc_html_e( 'HTML' , 'test-domain');
+	esc_attr_x( 'Attribute', 'Testing' , 'test-domain');
+	esc_html_x( 'HTML', 'Testing' , 'test-domain');
+}
\ No newline at end of file
diff --git a/tools/i18n/t/data/add-textdomain-0.php b/tools/i18n/t/data/add-textdomain-0.php
new file mode 100755
index 0000000000..f0555926f9
--- /dev/null
+++ b/tools/i18n/t/data/add-textdomain-0.php
@@ -0,0 +1,17 @@
+<?php
+function call_some_i18n_methods() {
+	__( 'Hello World' );
+	_e( 'Hello World' );
+	_n( 'Single', 'Plural', 1 );
+	_n_noop( 'Single Noop', 'Plural Noop', 1 );
+	_x( 'Hello World', 'Testing' );
+	_ex( 'Hello World', 'Testing' );
+	_nx( 'Hello World', 'Testing' );
+	_nx_noop( 'Hello World Noop', 'Testing' );
+	esc_attr__( 'Attribute' );
+	esc_html__( 'HTML' );
+	esc_attr_e( 'Attribute' );
+	esc_html_e( 'HTML' );
+	esc_attr_x( 'Attribute', 'Testing' );
+	esc_html_x( 'HTML', 'Testing' );
+}
\ No newline at end of file