diff --git a/test/a/textbook.en.md b/test/a/textbook.en.md
new file mode 100644
index 000000000..fb6668c6c
--- /dev/null
+++ b/test/a/textbook.en.md
@@ -0,0 +1,11 @@
+---
+lessons:
+    - slug: test01
+      order: 1
+    - slug: test02
+      order: 2
+    - slug: test03
+      order: 2
+---
+
+## TEST A
diff --git a/test/c/textbook.en.md b/test/c/textbook.en.md
new file mode 100644
index 000000000..1686c6dc1
--- /dev/null
+++ b/test/c/textbook.en.md
@@ -0,0 +1,11 @@
+---
+lessons:
+    - slug: test01
+      order: 3
+    - slug: test02
+      order: 3
+    - slug: test03
+      order: 1
+---
+
+## TEST C
diff --git a/test/d/textbook.en.md b/test/d/textbook.en.md
new file mode 100644
index 000000000..85a0caf1a
--- /dev/null
+++ b/test/d/textbook.en.md
@@ -0,0 +1,11 @@
+---
+lessons:
+    - slug: test01
+      order: 2
+    - slug: test02
+      order: 1
+    - slug: test03
+      order: 3
+---
+
+## TEST B