Test round-tripping of binary reel headers to and from a byte stream.

segpy/header.py

@@ -55,6 +55,22 @@ class Header:
     def __getattr__(self, name):
         raise AttributeError("Object of type {!r} has no attribute {!r}".format(self.__class__.__name__, name))
 
+    def __repr__(self):
+        return "{}({})".format(
+            self.__class__.__name__,
+            ', '.join("{}={}".format(k, getattr(self, k)) for k in self.ordered_field_names()))
+
+
+def are_equal(self, other):
+    """Compare two headers for equality.
+
+    Note:
+        This is not implemented as __eq__() to prevent recursive behaviour in the header descriptor.
+    """
+    if type(self) != type(other):
+        return False
+    return all(getattr(self, field_name) == getattr(other, field_name) for field_name in self.ordered_field_names())
+
 
 class FormatMeta(type):
     """A metaclass for header format classes.

segpy/toolkit.py

@@ -169,7 +169,6 @@ def read_binary_reel_header(fh, endian='>'):
             little-endian (non-standard)
     """
     header_packer = make_header_packer(BinaryReelHeader, endian)
-    fh.seek(TEXTUAL_HEADER_NUM_BYTES)  # Consider using from_one_based(BinaryReelHeader.START_OFFSET_IN_BYTES)
     buffer = fh.read(BinaryReelHeader.LENGTH_IN_BYTES)
     reel_header = header_packer.unpack(buffer)
     return reel_header

test/test_roundtrip.py

@@ -0,0 +1,24 @@
+import unittest
+from hypothesis import given
+from io import BytesIO
+from hypothesis.specifiers import sampled_from
+from segpy.binary_reel_header import BinaryReelHeader
+from segpy.header import are_equal
+
+from segpy.toolkit import write_binary_reel_header, read_binary_reel_header
+from test.strategies import header
+
+
+class TestBinaryReelHeader(unittest.TestCase):
+
+    @given(header(BinaryReelHeader),
+           sampled_from(['<', '>']))
+    def test_roundtrip(self, write_header, endian):
+        with BytesIO() as write_stream:
+            write_binary_reel_header(write_stream, write_header, endian)
+            written_steam = write_stream.getvalue()
+
+        with BytesIO(written_steam) as read_stream:
+            read_header = read_binary_reel_header(read_stream, endian)
+
+        self.assertTrue(are_equal(write_header, read_header))