Index: tests/phpunit/includes/bootstrap.php
===================================================================
--- tests/phpunit/includes/bootstrap.php	(revision 36327)
+++ tests/phpunit/includes/bootstrap.php	(working copy)
@@ -26,6 +26,8 @@
 define( 'WP_TESTS_TABLE_PREFIX', $table_prefix );
 define( 'DIR_TESTDATA', dirname( __FILE__ ) . '/../data' );
 
+define( 'WP_LANG_DIR', DIR_TESTDATA . '/languages' );
+
 if ( ! defined( 'WP_TESTS_FORCE_KNOWN_BUGS' ) )
 	define( 'WP_TESTS_FORCE_KNOWN_BUGS', false );
 
Index: tests/phpunit/tests/l10n.php
===================================================================
--- tests/phpunit/tests/l10n.php	(revision 36327)
+++ tests/phpunit/tests/l10n.php	(working copy)
@@ -26,4 +26,28 @@
 		$this->assertEquals( 'first-before-bar|second-before-bar', before_last_bar( 'first-before-bar|second-before-bar|after-last-bar' ) );
 	}
 
+	/**
+	 * @ticket 35284
+	 * @slowThreshold 700
+	 */
+	function test_wp_get_installed_translations_for_core() {
+		$installed_translations = wp_get_installed_translations( 'core' );
+		$this->assertInternalType( 'array', $installed_translations );
+		$this->assertNotEmpty( $installed_translations );
+
+		$textdomains_expected = array( 'admin', 'admin-network', 'continents-cities', 'default' );
+		$this->assertEqualSets( $textdomains_expected, array_keys( $installed_translations ) );
+
+		$this->assertNotEmpty( $installed_translations['default']['en_GB'] );
+		$data_en_GB = $installed_translations['default']['en_GB'];
+		$this->assertEquals( '2016-01-14 21:14:29+0000', $data_en_GB['PO-Revision-Date'] );
+		$this->assertEquals( 'Development (4.4.x)', $data_en_GB['Project-Id-Version'] );
+		$this->assertEquals( 'GlotPress/1.0-alpha-1100', $data_en_GB['X-Generator'] );
+
+		$this->assertNotEmpty( $installed_translations['admin']['es_ES'] );
+		$data_es_ES = $installed_translations['admin']['es_ES'];
+		$this->assertEquals( '2015-12-22 20:26:46+0000', $data_es_ES['PO-Revision-Date'] );
+		$this->assertEquals( 'Administration', $data_es_ES['Project-Id-Version'] );
+		$this->assertEquals( 'GlotPress/1.0-alpha-1100', $data_es_ES['X-Generator'] );
+	}
 }