Index: tests/phpunit/tests/basic.php
===================================================================
--- tests/phpunit/tests/basic.php	(revision 26862)
+++ tests/phpunit/tests/basic.php	(working copy)
@@ -29,6 +29,17 @@
 		$this->assertEquals( $version, trim( $matches[1] ), "readme.html's version needs to be updated to $version." );
 	}
 
+	function test_package_json() {
+		$package_json = file_get_contents( dirname( ABSPATH ) . '/package.json' );
+		$package_json = json_decode( $package_json , true );
+		list( $version ) = explode( '-', $GLOBALS['wp_version'] );
+		// package.json uses x.y.z, so fill cleaned $wp_version for .0 releases
+		if ( 1 == substr_count( $version, '.' ) ) {
+			$version .= '.0';
+		}
+		$this->assertEquals( $version, $package_json['version'], "package.json's version needs to be updated to $version." );
+	}
+
 	// two tests for a lame bug in PHPUnit that broke the $GLOBALS reference
 	function test_globals() {
 		global $test_foo;