Add tests for parsing a book with option "root"

lib/parse/__tests__/parseBook.js

@@ -26,4 +26,30 @@ describe('parseBook', function() {
             expect(books.size).toBe(2);
         });
     });
+
+    pit('should parse book in a directory', function() {
+        var fs = createMockFS({
+            'book.json': JSON.stringify({
+                root: './test'
+            }),
+            'test': {
+                'README.md': 'Hello World',
+                'SUMMARY.md': '# Summary\n\n* [Page](page.md)\n',
+                'page.md': 'Page'
+            }
+        });
+        var book = Book.createForFS(fs);
+
+        return parseBook(book)
+        .then(function(resultBook) {
+            var readme = resultBook.getReadme();
+            var summary = resultBook.getSummary();
+            var articles = summary.getArticlesAsList();
+
+            expect(summary.getFile().exists()).toBe(true);
+            expect(readme.getFile().exists()).toBe(true);
+            expect(articles.size).toBe(2);
+        });
+    });
+
 });