diff --git a/init.lua b/init.lua
index 4ff099e..27ee98a 100644
--- a/init.lua
+++ b/init.lua
@@ -6,6 +6,29 @@ local M = {}
 function M.run_tests(ctx)
     -- Assertions added in plan tasks 2-7.
 
+    -- ===== parse_lua_surface =====
+    do
+        local src = [[
+local M = {}
+M.foo = function(x) return x end
+M.bar = function() end
+M._private = function() end
+local function not_in_M() end
+return M
+]]
+        local surface = api.parse_lua_surface(src)
+        engine.test.equals(#surface.public, 2,  "parse_lua_surface: 2 public functions")
+        engine.test.equals(surface.public[1], "foo", "parse_lua_surface: first public is foo")
+        engine.test.equals(surface.public[2], "bar", "parse_lua_surface: second public is bar")
+        engine.test.equals(#surface.private, 1, "parse_lua_surface: 1 private function")
+        engine.test.equals(surface.private[1], "_private", "parse_lua_surface: private name = _private")
+
+        -- Edge: empty source
+        local empty = api.parse_lua_surface("local M = {}\nreturn M")
+        engine.test.equals(#empty.public, 0, "parse_lua_surface: empty source = no public")
+        engine.test.equals(#empty.private, 0, "parse_lua_surface: empty source = no private")
+    end
+
     engine.exit(engine.test.failures())
 end