diff --git a/testdata/initial.atom b/testdata/initial.atom
new file mode 100644
index 0000000..b086591
--- /dev/null
+++ b/testdata/initial.atom
@@ -0,0 +1,8 @@
+<feed xmlns="http://www.w3.org/2005/Atom">
+	<title type="text">Some title</title>
+	<id>http://www.example.com/feed/atom/</id>
+	<entry>
+		<title>First title</title>
+		<id>1</id>
+	</entry>
+</feed>
diff --git a/testdata/initial_plus_one_new.atom b/testdata/initial_plus_one_new.atom
new file mode 100644
index 0000000..2461a66
--- /dev/null
+++ b/testdata/initial_plus_one_new.atom
@@ -0,0 +1,12 @@
+<feed xmlns="http://www.w3.org/2005/Atom">
+	<title type="text">Some title</title>
+	<id>http://www.example.com/feed/atom/</id>
+	<entry>
+		<title>First title</title>
+		<id>1</id>
+	</entry>
+	<entry>
+		<title>Second title</title>
+		<id>2</id>
+	</entry>
+</feed>