test: Initial test work

test/dllist_test.gleam

@@ -1,13 +1,21 @@
-import gleeunit
+import dllist
+import startest
 
 pub fn main() -> Nil {
-  gleeunit.main()
+  startest.run(startest.default_config())
 }
 
-// gleeunit test functions end in `_test`
-pub fn hello_world_test() {
-  let name = "Joe"
-  let greeting = "Hello, " <> name <> "!"
+pub fn is_empty_tests() {
+  startest.describe("is_emtpy", [
+    startest.it("terminated list", fn() {
+      assert dllist.is_empty(dllist.new())
 
-  assert greeting == "Hello, Joe!"
+      assert !dllist.is_empty(dllist.new() |> dllist.insert(1))
+    }),
+    startest.it("cyclic list", fn() {
+      assert dllist.is_empty(dllist.new_cyclic())
+
+      assert !dllist.is_empty(dllist.new_cyclic() |> dllist.insert(1))
+    }),
+  ])
 }