Add python fields tests

Fields of all currently existing types are verified, but not all fields
as it would be somewhat repeating "application" tests and chance of
error here is small.

Author: achaikou

python/test/segy.py

@@ -937,6 +937,108 @@ def test_write_header_update_atomic(small):
         assert header == f.header[10]
 
 
+def test_field_types_read():
+    with segyio.open(testdata / 'decrement.sgy', "r", ignore_geometry=True) as f:
+        bdec = f.bin
+        tdec = f.header[3]
+
+        assert bdec[BinField.NrTracesInStream] == 18446744073709551572
+        assert bdec[BinField.JobID] == 2147483647
+        assert bdec[BinField.SamplesOriginal] == 65526
+        assert bdec[BinField.VerticalSum] == 32755
+        assert bdec[BinField.SEGYRevisionMinor] == 217
+        assert bdec[BinField.ExtIntervalOriginal] == 1125899906842593.0
+
+        assert tdec[TraceField.INLINE_3D] == 2147483355
+        assert tdec[TraceField.TRACE_SAMPLE_COUNT] == 65382
+        assert tdec[TraceField.DelayRecordingTime] == 32627
+
+    with segyio.open(testdata / 'increment.sgy', "r", ignore_geometry=True) as f:
+        binc = f.bin
+        tinc = f.header[3]
+
+        assert binc[BinField.NrTracesInStream] == 43
+        assert binc[BinField.JobID] == -2147483648
+        assert binc[BinField.SamplesOriginal] == 8
+        assert binc[BinField.VerticalSum] == -32756
+        assert binc[BinField.SEGYRevisionMinor] == 37
+        assert binc[BinField.ExtIntervalOriginal] == -1125899906842593.0
+
+        assert tinc[TraceField.INLINE_3D] == -2147483356
+        assert tinc[TraceField.TRACE_SAMPLE_COUNT] == 152
+        assert tinc[TraceField.DelayRecordingTime] == -32628
+
+
+@tmpfiles(testdata / 'small.sgy')
+def test_field_types_write(tmpdir):
+    updpath = tmpdir / 'small.sgy'
+
+    with segyio.open(updpath, ignore_geometry=True) as f:
+        orig_binh = f.bin
+        orig_trh = f.header[0]
+
+    with segyio.open(updpath, mode='r+', ignore_geometry=True) as f:
+        bupd = {
+            BinField.NrTracesInStream: 18446744073709551615,
+            BinField.JobID: 2147483647,
+            BinField.SamplesOriginal: 65535,
+            BinField.VerticalSum: -32768,
+            BinField.SEGYRevisionMinor: 255,
+            BinField.ExtIntervalOriginal: 10.125,
+        }
+
+        tupd = {
+            TraceField.INLINE_3D: -2147483648,
+            TraceField.TRACE_SAMPLE_COUNT: 65535,
+            TraceField.DelayRecordingTime: 32767,
+        }
+
+        f.bin.update(bupd)
+        f.header[0].update(tupd)
+        f.flush()
+
+    with segyio.open(updpath, ignore_geometry=True) as f:
+        binh = f.bin
+        trh = f.header[0]
+
+        assert orig_binh != binh
+        assert orig_trh != trh
+
+        for k, v in bupd.items():
+            assert binh[k] == v
+
+        for k, v in tupd.items():
+            assert trh[k] == v
+
+
+@tmpfiles(testdata / 'small.sgy')
+def test_field_types_bad_write(tmpdir):
+    updpath = tmpdir / 'small.sgy'
+
+    with segyio.open(updpath, ignore_geometry=True) as f:
+        binh = f.bin
+
+    with segyio.open(updpath, mode='r+', ignore_geometry=True) as f:
+        bad = {
+            BinField.NrTracesInStream: [18446744073709551616],
+            BinField.JobID: [18446744073709551616, 2147483648],
+            BinField.SamplesOriginal: [65536, -1],
+            BinField.VerticalSum: [-32769],
+            BinField.SEGYRevisionMinor: [256, -127],
+            BinField.ExtIntervalOriginal: ["wrong"],
+        }
+
+        for k, vlist in bad.items():
+            for v in vlist:
+                with pytest.raises(ValueError, match="out of range"):
+                    f.bin[k] = v
+
+        f.flush()
+
+    with segyio.open(updpath, ignore_geometry=True) as f:
+        assert binh == f.bin
+
+
 def test_fopen_error():
     # non-existent file
     with pytest.raises(IOError):