Add type checking tests

lib/analysis.ml

@@ -29,12 +29,31 @@ let () =
     | _ -> None)
 
 (** After [infer_expr ctx hint expr], [expr] will be assigned a type based on
-    [hint] and [ctx].
+    [ctx] and [hint].
 
     @raise TypeInferenceError on failure. *)
 let rec infer_expr ctx hint expr =
   match expr with
-  | Var var -> var.ty <- Context.get ctx var.name
+  | Var var ->
+      var.ty <- Context.get ctx var.name;
+      if var.ty = None then
+        raise
+          (TypeInferenceError
+             {
+               domain = "resolution";
+               symbol = Some var.name;
+               ast = Left expr;
+               unify = None;
+             })
+      else if hint <> None && var.ty <> hint then
+        raise
+          (TypeInferenceError
+             {
+               domain = "unification";
+               symbol = Some var.name;
+               ast = Left expr;
+               unify = Some (Option.get hint, Option.get var.ty);
+             })
   | ConstInt _ -> (
       match hint with
       | None | Some (Type.Primitive Int63) | Some Any -> ()
@@ -111,6 +130,7 @@ let infer_stmt ctx stmt =
                     unify = Some (t1, t2);
                   }));
       Context.insert ctx name (type_of_expr expr |> Option.get)
+  | Print expr -> infer_expr ctx None expr
   | _ -> ()
 
 let infer prog =

lib/ast.ml

@@ -80,12 +80,15 @@ let rec pp_expr fmt = function
   | Infix { lhs; op; rhs; _ } ->
       Format.pp_print_string fmt "(";
       pp_expr fmt lhs;
+      Format.pp_print_string fmt " ";
       pp_op fmt op;
+      Format.pp_print_string fmt " ";
       pp_expr fmt rhs;
       Format.pp_print_string fmt ")"
   | Prefix { op; rhs; _ } ->
       Format.pp_print_string fmt "(";
       pp_op fmt op;
+      Format.pp_print_string fmt " ";
       pp_expr fmt rhs;
       Format.pp_print_string fmt ")"
   | FunctionExpr _ -> Format.pp_print_string fmt "<func>"

test/snapshot.ml

@@ -3,11 +3,9 @@ open Cs3110_compiler
 
 type transform = string -> string -> string
 
-(** Used to categorize snapshots by validity in version. *)
-let version_string = Meta.Version.to_string Meta.get.version
-
-let make_test_suite (root : string) (transform : transform) : unit test =
+let make_test_suite ?(version = Meta.get.version) root transform =
   let open Util in
+  let version_string = Meta.Version.to_string version in
   let snapshot_folder =
     Util.merge_paths [ Project_root.path; root; version_string ]
   in
@@ -25,7 +23,7 @@ let make_test_suite (root : string) (transform : transform) : unit test =
     let input = read_file input_path in
     let expected = read_file output_path in
     try
-      let actual = transform input_path input in
+      let actual = transform (snapshot ^ ".in") input in
       (check string)
         "Using the given input transformer should yield matching output to the \
          expected."

test/snapshot.mli

@@ -1,10 +1,14 @@
-open Alcotest
-
 (** Let [f] be of type [transform]. Then, [f path contents] is the result of
-    transforming the string [contents] (from the file at path [path]). *)
+    transforming the string [contents] (from the file at path [path] relative to
+    the version root, e.g., for version v1.0.4, relative to
+    [test/snapshots/v1.0.4]). *)
 type transform = string -> string -> string
 
 (** [make_test_suite name f] is a snapshot test suite named [name] for version
     [Meta.get.version] using snapshot transformation [f] (see the documentation
-    for [transform]). *)
-val make_test_suite : string -> transform -> unit test
+    for [transform]). Optionally, the version can be manually specified. *)
+val make_test_suite :
+  ?version:Cs3110_compiler.Meta.Version.t ->
+  string ->
+  transform ->
+  unit Alcotest.test

test/snapshots/v0.1.0/type0.in

@@ -0,0 +1 @@
+print true

test/snapshots/v0.1.0/type0.out

@@ -0,0 +1 @@
+print true

test/snapshots/v0.1.0/type1.in

@@ -0,0 +1,3 @@
+let x = 1
+let y = 2
+let z = x + y

test/snapshots/v0.1.0/type1.out

@@ -0,0 +1,3 @@
+let x: Int = 1
+let y: Int = 2
+let z: Int = (x + y)

test/snapshots/v0.1.0/type2.in

@@ -0,0 +1,2 @@
+let x = 4
+let y = *4

test/snapshots/v0.1.0/type2.out

@@ -0,0 +1 @@
+Type unification error: attempt to unify ?* and Int

test/snapshots/v0.1.0/type3.in

@@ -0,0 +1,3 @@
+let x = 1
+let y = true
+print x + y

test/snapshots/v0.1.0/type3.out

@@ -0,0 +1 @@
+Type unification error (symbol='y'): attempt to unify Int and Bool

test/snapshots/v0.1.0/type4.in

@@ -0,0 +1 @@
+print x

test/snapshots/v0.1.0/type4.out

@@ -0,0 +1 @@
+Type resolution error (symbol='x')

test/test_cs3110_compiler.ml

@@ -1,20 +1,3 @@
-let interpreter_transform path input =
-  ignore path;
-  let open Cs3110_compiler in
-  let interpreter = Interpreter.create () in
-  let stdout = ref "" in
-  let statements = Parse_lex.lex_and_parse input in
-  interpreter.set_mode (Text stdout);
-  List.iter interpreter.step statements;
-  stdout
-
-let () = ignore interpreter_transform
-
-let ir_transform path input =
-  ignore path;
-  ignore input;
-  ""
-
 let id_module_test_suite =
   let open Alcotest in
   let id_gens_isolated_test n () =
@@ -139,11 +122,44 @@ let cfg_module_test_suite =
   in
   ("lib/control_flow_graph.mli", [ test_1 ])
 
+let snapshot_test_suite =
+  let interpreter_transform path input =
+    ignore path;
+    let open Cs3110_compiler in
+    let interpreter = Interpreter.create () in
+    let stdout = ref "" in
+    let statements = Parse_lex.lex_and_parse input in
+    interpreter.set_mode (Text stdout);
+    List.iter interpreter.step statements;
+    stdout
+  in
+  let () = ignore interpreter_transform in
+  let transform path input =
+    let open Cs3110_compiler in
+    let open Util in
+    let stmt_to_string stmt =
+      Ast.pp_stmt Format.str_formatter stmt;
+      Format.flush_str_formatter ()
+    in
+    if String.starts_with ~prefix:"type" path then
+      try
+        let statements = Parse_lex.lex_and_parse input in
+        Analysis.infer statements;
+        List.map (stmt_to_string >> fun s -> s ^ "\n") statements
+        |> String.concat ""
+      with
+      | Analysis.TypeInferenceError err ->
+          Printexc.to_string (Analysis.TypeInferenceError err) ^ "\n"
+      | e -> raise e
+    else ""
+  in
+  Snapshot.make_test_suite "test/snapshots" transform
+
 let () =
   [
     util_module_test_suite;
     id_module_test_suite;
     cfg_module_test_suite;
-    Snapshot.make_test_suite "test/snapshots" ir_transform;
+    snapshot_test_suite;
   ]
   |> Alcotest.run "x86ISTMB"