1 files changed, 65 insertions, 0 deletions
diff --git a/tests/expression_type_of.ml b/tests/expression_type_of.ml
new file mode 100644
index 0000000..706b3e7
--- /dev/null
+++ b/tests/expression_type_of.ml
@@ -0,0 +1,65 @@
+open OUnit2
+module T = ImportExpression.T
+module Types = ImportDataTypes.Types
+module Expr = Expression_builder
+module M = Expr.Make (ImportExpression.Type_of)
+
+let eval = M.eval ~path_repr:(fun _ -> ())
+let printer = Types.string_of_t
+let test_expr expr = ImportExpression.Type_of.observe expr
+
+let empty =
+  "empty" >:: fun _ ->
+  let expr = eval Expr.empty in
+  let content = test_expr expr and expected = Types.None in
+
+  assert_equal ~printer expected content
+
+(** Control an if statement with a predicate which is not a boolean *)
+let invalid_if =
+  "invalid_if" >:: fun _ ->
+  (* The expression we want to test *)
+  let raw_expr =
+    Expr.if_ Expr.literal_test Expr.integer_zero Expr.integer_one
+  in
+
+  let exn =
+    ImportErrors.TypeError
+      {
+        expected = Types.Bool;
+        actual = Types.String;
+        expression = ImportExpression.Repr.repr Fun.id raw_expr;
+        subset = "the predicate";
+      }
+  in
+  assert_raises exn (fun () ->
+      let expr = eval raw_expr in
+      test_expr expr)
+
+(** The application should infer that the expression is a string *)
+let valid_if =
+  "valid_if" >:: fun _ ->
+  let expr =
+    eval
+    @@ Expr.if_
+         (Expr.equal Expr.integer_one Expr.integer_zero)
+         Expr.literal_test Expr.literal_test
+  in
+  let content = test_expr expr and expected = Types.String in
+  assert_equal ~printer expected content
+
+let upper =
+  "upper" >:: fun _ ->
+      let expr = eval @@ Expr.function' T.Upper [Expr.literal_test] in
+
+  let content = test_expr expr and expected = Types.String in
+  assert_equal ~printer expected content
+
+let in_int =
+  "in_int" >:: fun _ ->
+  let expr = eval @@ Expr.in_ (Expr.path "external") [ Expr.integer_one ] in
+  let content = test_expr expr and expected = Types.Bool in
+  assert_equal ~printer expected content
+
+let tests = "expression_type_of" >::: [ empty; invalid_if; valid_if; in_int ;
+upper ]