spec(teal_type_definition): add basic test

spec/printer/teal_type_definition_spec.tl

@@ -0,0 +1,35 @@
+local assert = require("luassert")
+local type Node = require("types.Node")
+local stringx = require("pl.stringx")
+local teal_type_definition_printer = require("printer.teal_type_definition")
+
+local printer = teal_type_definition_printer.printer
+
+-- We need to remove the last newline inserted by Penlight's dedent
+local function dedent(str: string): string
+   return (stringx.dedent(str):sub(1, -3))
+end
+
+local function gen(ast: Node, expected_code: string): function()
+   return function()
+      local generated = printer(ast)
+      assert.same(dedent(expected_code), generated)
+   end
+end
+
+describe("Print Teal type definition", function()
+   it("should print a simple module type definition", gen(
+      {
+         children = {},
+         name = "Empty",
+         token = "module",
+      },
+      [[
+         -- This file was auto-generated.
+
+         local record Empty
+         end
+
+         return Empty
+      ]]))
+end)