add unit test for config module

test/config_test.gleam

@@ -0,0 +1,18 @@
+import config
+import gleeunit
+import gleeunit/should
+
+pub fn main() -> Nil {
+  gleeunit.main()
+}
+
+// gleeunit test functions end in `_test`
+pub fn file_read_test() {
+  let assert Ok(cfg) = config.load_config()
+
+  cfg.mqtt_host
+  |> should.equal("192.168.1.11")
+
+  cfg.mqtt_user
+  |> should.equal("homeassistant")
+}

test/weather_portal_test.gleam

@@ -3,11 +3,3 @@ import gleeunit
 pub fn main() -> Nil {
   gleeunit.main()
 }
-
-// gleeunit test functions end in `_test`
-pub fn hello_world_test() {
-  let name = "Joe"
-  let greeting = "Hello, " <> name <> "!"
-
-  assert greeting == "Hello, Joe!"
-}