Infer scalar types with let generalization

test/test_harness.ml

@@ -63,3 +63,32 @@ let run_suite suite cases =
 let failure_count () = !failures
 
 let case_count () = !cases
+
+let root () = try Sys.getenv "DELTA_ROOT" with Not_found -> "."
+
+let fixture name = Filename.concat (root ()) (Filename.concat "test/fixture" name)
+
+let read_fixture name = Native.read_file (fixture name)
+
+let error_of thunk =
+  try
+    ignore (thunk ());
+    None
+  with Diagnostic.Error diagnostic -> Some diagnostic
+
+let parse text = Parse.program text
+
+let resolve text = Resolve.program (parse text)
+
+let infer text = Infer.program (resolve text)
+
+let parse_error text = error_of (fun () -> parse text)
+
+let resolve_error text = error_of (fun () -> resolve text)
+
+let infer_error text = error_of (fun () -> infer text)
+
+let check_message name expected thunk =
+  match error_of thunk with
+  | None -> fail name "expected a diagnostic"
+  | Some diagnostic -> check_equal_string name expected diagnostic.Diagnostic.message