Fix W0017 documentation

Summary:
Address #23
- Fix reported documentation error
- Add test to confirm the normal operation for the provided repro case

Reviewed By: robertoaloi

Differential Revision: D56413056

fbshipit-source-id: eaaea7279c5661135ce03d7444535c4088ef58b0

crates/ide/src/diagnostics/undefined_function.rs

@@ -229,6 +229,27 @@ mod tests {
         )
     }
 
+    #[test]
+    fn module_macro() {
+        // https://github.com/WhatsApp/erlang-language-platform/issues/23
+        check_diagnostics(
+            r#"
+            //- /src/elp_w0017.erl
+            -module(elp_w0017).
+            -export([loop/0]).
+
+            loop() ->
+              timer:sleep(1000),
+              ?MODULE:loop().
+
+            //- /src/timer.erl
+            -module(timer).
+            -export([sleep/1]).
+            sleep(X) -> X.
+            "#,
+        )
+    }
+
     #[test]
     fn test_ignore_fix() {
         check_fix(

website/docs/erlang-error-index/w/W0017.md

@@ -2,7 +2,7 @@
 sidebar_position: 17
 ---
 
-# W0017 - Unused Function
+# W0017 - Undefined Function
 
 ## Error