Add tests for small signed integers

test/dune

@@ -1,5 +1,5 @@
 (tests
   (package integers)
   (libraries integers)
-  (names hexprinting uint64conversions uint32conversions))
+  (names hexprinting uint64conversions uint32conversions smallsint))
 

test/smallsint.ml

@@ -0,0 +1,81 @@
+let () = print_endline "Small int operations test: ?"
+
+(* Asserting max and min integers are correct *)
+let () =
+  let check8 expected res =
+    let open Signed.Int8 in
+    let equal : int -> int -> bool = Stdlib.( = ) in
+    equal expected (to_int res) in
+  let check16 expected res =
+    let open Signed.Int16 in
+    let equal : int -> int -> bool = Stdlib.( = ) in
+    equal expected (to_int res) in
+  assert (check8 127 Signed.Int8.max_int);
+  assert (check8 (- 128) Signed.Int8.min_int);
+  assert (check16 32767 Signed.Int16.max_int);
+  assert (check16 (- 32768) Signed.Int16.min_int)
+
+(* Asserting that integer conversions correctly overflow *)
+let () =
+  let open Signed.Int8 in
+  let check expected res =
+    let equal : int -> int -> bool = Stdlib.( = ) in
+    equal expected (to_int res) in
+  assert (check 0 zero);
+  assert (check (- 1) minus_one);
+  assert (check 127 (of_int 127));
+  assert (check (- 128) (of_int 128));
+  assert (check (- 64) (of_int 192))
+
+(* Asserting that roundtrip int -> string -> int conversions survive *)
+let () =
+  let open Signed.Int8 in
+  let check i =
+    let str = to_string i in
+    equal i (of_string str)
+  in
+  assert (check (of_int 1));
+  assert (check (of_int 127));
+  assert (check (of_int (- 128)));
+  assert (check (of_int 192))
+
+(* Asserting that addition performs as expected *)
+let () =
+  let open Signed.Int8 in
+  let check expected res =
+    let equal : int -> int -> bool = Stdlib.( = ) in
+    equal expected (to_int res) in
+  assert (check 1 (add zero one));
+  assert (check (- 128) (add max_int one));
+  assert (check (- 65) (add max_int (of_int 64)))
+
+(* Asserting that subtraction performs as expected *)
+let () =
+  let open Signed.Int8 in
+  let check expected res =
+    let equal : int -> int -> bool = Stdlib.( = ) in
+    equal expected (to_int res) in
+  assert (check (- 1) (sub zero one));
+  assert (check 127 (sub min_int one));
+  assert (check 64 (sub min_int (of_int 64)))
+
+(* Asserting that multiplication performs as expected *)
+let () =
+  let open Signed.Int8 in
+  let check expected res =
+    let equal : int -> int -> bool = Stdlib.( = ) in
+    equal expected (to_int res) in
+  assert (check (- 1) (mul minus_one one));
+  assert (check (- 128) (mul minus_one min_int));
+  assert (check (- 2) (mul max_int (of_int 2)))
+
+(* Asserting that logical right shifting performs as expected *)
+let () =
+  let open Signed.Int8 in
+  let check expected res =
+    let equal : int -> int -> bool = Stdlib.( = ) in
+    equal expected (to_int res) in
+  assert (check (- 1) (shift_right_logical minus_one 0));
+  assert (check 127 (shift_right_logical minus_one 1))
+
+let () = print_endline "Small int operations test: ✓"