Merge pull request #62 from GlobalFishingWatch/PIPELINE-1942

Don't fail on type 5 messages with bad padding value

ais_tools/ais.py

@@ -1,5 +1,6 @@
 from ais_tools.transcode import DecodeError
 from ais_tools.transcode import ASCII8toAIS6
+from ais_tools import ais5
 from ais_tools import ais8
 from ais_tools import ais9
 from ais_tools import ais18
@@ -18,6 +19,7 @@
 }
 
 decode_fn = {
+    5: ais5.ais5_decode,
     8: ais8.ais8_decode,
     9: ais9.ais9_decode,
     18: ais18.ais18_decode,

ais_tools/ais5.py

@@ -0,0 +1,10 @@
+import ais as libais
+from ais import DecodeError
+
+
+def ais5_decode(body, pad):
+    try:
+        return libais.decode(body, 2)
+    except DecodeError as e:
+        raise DecodeError(f'TYPE 5 LIBAIS ERR: {str(e)}')
+

pyproject.toml

@@ -6,7 +6,7 @@ build-backend = "setuptools.build_meta"
 name = "ais-tools"
 description = "Tools for managing AIS messages"
 readme = "README.md"
-version = "v0.1.6.dev9"
+version = "v0.1.7"
 license = {file = "LICENSE"}
 authors = [
     {name = "Paul Woods", email = "paul@globalfishingwatch.org"},

tests/test_ais.py

@@ -81,6 +81,30 @@ def test_ais8_wrong_pad():
     assert ('83am8S@j<d8dtfMEuj9loFOM6@0', 2) == AISMessageTranscoder.encode_nmea(msg)
 
 
+@pytest.mark.parametrize("body,pad,expected", [
+    # incorrect padding
+    ('56:=31`000008QaF220QD60`T4pN3N2222222216>pN5@50e0ES2@C`6EC`1hCQp8888880', 0,
+     {'name': 'HUA JIANG 7         '}),
+    # correct padding
+    ('56:=31`000008QaF220QD60`T4pN3N2222222216>pN5@50e0ES2@C`6EC`1hCQp8888880', 2,
+     {'name': 'HUA JIANG 7         '})
+     ])
+def test_ais5(body, pad, expected):
+    msg = AISMessageTranscoder.decode_nmea(body, pad)
+    actual = {k: v for k, v in msg.items() if k in expected}
+    assert actual == expected
+
+
+@pytest.mark.parametrize("body,pad,expected", [
+    # incorrect padding
+    ('56:=31`000008QaF220QD60`T4pN3N2222222216>pN5@50e0ES2@C`6EC`1hCQp88888809999', 0,
+     'TYPE 5 LIBAIS ERR: Ais5: AIS_ERR_BAD_BIT_COUNT'),
+])
+def test_ais5_fail(body, pad, expected):
+    with pytest.raises(DecodeError, match=expected):
+        _ = AISMessageTranscoder.decode_nmea(body, pad)
+
+
 @pytest.mark.parametrize("body,pad,expected", [
     ('9001?BP=h:qJ9vb;:f7EN1h240Rb', 0, {'mmsi': 20298, 'alt': 55, 'sog': 10}),
     ('90009C3dRIM1QSsjSPAa1;h200T4', 0, {'mmsi': 2380, 'alt': 946, 'alt_sensor': 0}),