From 38a91b14cfdf796bf10aeb1344ac3eadd724ba68 Mon Sep 17 00:00:00 2001
From: davidalo <davidalto97@gmail.com>
Date: Sat, 16 Mar 2024 11:31:15 +0100
Subject: [PATCH] Fix ROT decode rounding (#130)

---
 pyais/messages.py    |  2 +-
 tests/test_decode.py | 21 +++++++++++++++++----
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/pyais/messages.py b/pyais/messages.py
index c819129..3f6ef48 100644
--- a/pyais/messages.py
+++ b/pyais/messages.py
@@ -777,7 +777,7 @@ def to_turn(turn: typing.Union[int, float]) -> typing.Union[float, TurnRate]:
     elif abs(turn) == 128:
         return TurnRate.NO_TI_DEFAULT
 
-    return math.copysign(int((turn / 4.733) ** 2), turn)
+    return math.copysign(round((turn / 4.733) ** 2), turn)
 
 
 def from_turn(turn: typing.Optional[typing.Union[int, float, TurnRate]]) -> int:
diff --git a/tests/test_decode.py b/tests/test_decode.py
index 79cdf5a..7d8bb49 100644
--- a/tests/test_decode.py
+++ b/tests/test_decode.py
@@ -1364,12 +1364,25 @@ def test_rot_encode_yields_expected_values(self):
         encoded = encode_dict({"msg_type": 1, "mmsi": 123, "turn": 64.0})[0]
         assert encoded == "!AIVDO,1,1,,A,10000Nh9P0000000000000000000,0*6A"
 
+    def test_rot_encode_decode(self):
+        encoded = encode_dict({"msg_type": 1, "mmsi": 123, "turn": 2.0})[0]
+        assert decode(encoded).turn == 2.0
+
+        encoded = encode_dict({"msg_type": 1, "mmsi": 123, "turn": 3.0})[0]
+        assert decode(encoded).turn == 3.0
+
+        encoded = encode_dict({"msg_type": 1, "mmsi": 123, "turn": 4.0})[0]
+        assert decode(encoded).turn == 4.0
+
+        encoded = encode_dict({"msg_type": 1, "mmsi": 123, "turn": 5.0})[0]
+        assert decode(encoded).turn == 5.0
+
     def test_rot_decode_yields_expected_values(self):
-        assert decode(b"!AIVDM,1,1,,A,14QIG<5620KF@Gl:L9DI4o8N0P00,0*28").turn == 25.0
+        assert decode(b"!AIVDM,1,1,,A,14QIG<5620KF@Gl:L9DI4o8N0P00,0*28").turn == 26.0
         assert decode(b"!AIVDM,1,1,,B,13u><=gsQj0mQW:Q1<wRL28P0@:4,0*32").turn == -14.0
-        assert decode(b"!AIVDM,1,1,,A,14SSRt021O0?bK@MO7H6QUA600Rg,0*12").turn == 2.0
-        assert decode(b"!AIVDM,1,1,,2,13aB:Hhuh0PHjEFNKJg@11sH08J=,0*1E").turn == -3.0
-        assert decode(b"!AIVDM,1,1,,A,16:VFv0k0I`KQPpFATG4SgvT40:v,0*7B").turn == -120.0
+        assert decode(b"!AIVDM,1,1,,A,14SSRt021O0?bK@MO7H6QUA600Rg,0*12").turn == 3.0
+        assert decode(b"!AIVDM,1,1,,2,13aB:Hhuh0PHjEFNKJg@11sH08J=,0*1E").turn == -4.0
+        assert decode(b"!AIVDM,1,1,,A,16:VFv0k0I`KQPpFATG4SgvT40:v,0*7B").turn == -121.0
         assert decode(b"!AIVDM,1,1,,B,16:D3F0:15`5ogh<O?bk>1Dd2L1<,0*0B").turn == 71.0
 
     def test_get_sotdma_comm_state_utc_direct(self):