diff --git a/.gitmodules b/.gitmodules
index e21cc05..0ce3ef5 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,3 +4,6 @@
 [submodule "lib/cozette-sml"]
 	path = lib/cozette-sml
 	url = https://github.com/hummy123/cozette-sml
+[submodule "tests/Railroad"]
+	path = tests/Railroad
+	url = https://github.com/PerplexSystems/Railroad
diff --git a/shf-tests.mlb b/shf-tests.mlb
new file mode 100644
index 0000000..3a91cae
--- /dev/null
+++ b/shf-tests.mlb
@@ -0,0 +1,34 @@
+$(SML_LIB)/basis/basis.mlb
+
+(* FUNCTIONAL CORE *)
+
+lib/brolib-sml/src/line_gap.sml
+lib/cozette-sml/fonts/cozette-ascii.mlb
+
+message-types/input-msg.sml
+message-types/draw-msg.sml
+message-types/mailbox-type.sml
+
+fcore/bin-search.sml
+fcore/search-list.sml
+
+fcore/app-type.sml
+fcore/app-with.sml
+
+fcore/build-search-list.sml
+fcore/text-constants.sml
+ann
+  "allowVectorExps true"
+in
+  fcore/rect.sml
+  fcore/text-builder.sml
+end
+fcore/cursor.sml
+fcore/text-window.sml
+
+fcore/app-update.sml
+
+(* TEST FILES *)
+
+test/Railroad/src/railroad.mlb
+test/test.sml
diff --git a/test/README.md b/test/README.md
new file mode 100644
index 0000000..ed8385f
--- /dev/null
+++ b/test/README.md
@@ -0,0 +1,7 @@
+# shf-tests
+
+Unit tests for shf. 
+
+The tests require (Railroad)[https://github.com/PerplexSystems/Railroad] testing framework.
+
+
diff --git a/test/Railroad b/test/Railroad
new file mode 160000
index 0000000..3154a78
--- /dev/null
+++ b/test/Railroad
@@ -0,0 +1 @@
+Subproject commit 3154a783c0f5e01e17578ffb1d2209bf68496596
diff --git a/test/test.sml b/test/test.sml
new file mode 100644
index 0000000..e69de29