addition background image and getSlideBackground tests

test/test.html

@@ -19,13 +19,13 @@
 
 			<div class="slides">
 
-				<section>
+				<section data-background-image="examples/assets/image1.png">
 					<h1>1</h1>
 					<img data-src="fake-url.png">
 				</section>
 
 				<section>
-					<section>
+					<section data-background="examples/assets/image2.png">
 						<h1>2.1</h1>
 					</section>
 					<section>

test/test.js

@@ -114,11 +114,13 @@ Reveal.addEventListener( 'ready', function() {
 	});
 
 	test( 'Reveal.getSlideBackground', function() {
-		var firstBackground = document.querySelector( '.reveal .backgrounds>.slide-background:first-child' );
+		equal( Reveal.getSlideBackground( 0 ), document.querySelector( '.reveal .backgrounds>.slide-background:first-child' ), 'gets correct first background' );
+		equal( Reveal.getSlideBackground( 1 ), document.querySelector( '.reveal .backgrounds>.slide-background:nth-child(2)' ), 'no v index returns stack' );
+		equal( Reveal.getSlideBackground( 1, 0 ), document.querySelector( '.reveal .backgrounds>.slide-background:nth-child(2) .slide-background:nth-child(1)' ), 'v index 0 returns first vertical child' );
+		equal( Reveal.getSlideBackground( 1, 1 ), document.querySelector( '.reveal .backgrounds>.slide-background:nth-child(2) .slide-background:nth-child(2)' ), 'v index 1 returns second vertical child' );
 
-		equal( Reveal.getSlideBackground( 0 ), firstBackground, 'gets correct first background' );
-
-		strictEqual( Reveal.getSlideBackground( 100 ), undefined, 'returns undefined when background can\'t be found' );
+		strictEqual( Reveal.getSlideBackground( 100 ), undefined, 'undefined when out of horizontal bounds' );
+		strictEqual( Reveal.getSlideBackground( 1, 100 ), undefined, 'undefined when out of vertical bounds' );
 	});
 
 	test( 'Reveal.getPreviousSlide/getCurrentSlide', function() {
@@ -470,6 +472,15 @@ Reveal.addEventListener( 'ready', function() {
 		strictEqual( document.querySelectorAll( '.reveal section img[src]' ).length, 1, 'Image source has been set' );
 	});
 
+	test( 'background images', function() {
+		var imageSource1 = Reveal.getSlide( 0 ).getAttribute( 'data-background-image' );
+		var imageSource2 = Reveal.getSlide( 1, 0 ).getAttribute( 'data-background' );
+
+		// check that the images are applied to the background elements
+		ok( Reveal.getSlideBackground( 0 ).style.backgroundImage.indexOf( imageSource1 ) !== -1, 'data-background-image worked' );
+		ok( Reveal.getSlideBackground( 1, 0 ).style.backgroundImage.indexOf( imageSource2 ) !== -1, 'data-background worked' );
+	});
+
 
 	// ---------------------------------------------------------------
 	// EVENT TESTS