Added test modules for encoder, implemented basic test

da/dispersal.py

@@ -52,5 +52,3 @@ class Dispersal:
                     attestations.append(attestation)
             if len(attestations) >= self.threshold:
                 return self._build_certificate(attestations)
-
-

da/encoder.py

@@ -3,9 +3,10 @@ from typing import List
 from eth2spec.eip7594.mainnet import KZGCommitment as Commitment, KZGProof as Proof
 
 
+@dataclass
 class DAEncoderParams:
     column_count: int
-    element_size: int
+    bytes_per_field_element: int
 
 
 @dataclass

da/test_encoder.py

@@ -0,0 +1,27 @@
+from unittest import TestCase
+
+from da import encoder
+from da.encoder import DAEncoderParams
+from eth2spec.eip7594.mainnet import BYTES_PER_FIELD_ELEMENT
+
+
+class TestEncoder(TestCase):
+    def assert_encoding(self, encoder_params: DAEncoderParams, data: bytearray):
+        encoded_data = encoder.DAEncoder(encoder_params).encode(data)
+        self.assertEqual(encoded_data.data, data)
+        self.assertEqual(len(encoded_data.columns), encoder_params.column_count)
+        self.assertEqual(len(encoded_data.column_proofs), encoder_params.column_count)
+        chunks_size = (len(data) // encoder_params.bytes_per_field_element) // encoder_params.column_count
+        self.assertEqual(len(encoded_data.row_commitments), chunks_size)
+        self.assertEqual(len(encoded_data.row_proofs), chunks_size)
+
+    def test_encode(self):
+        from random import randbytes
+        sizes = [pow(2, exp) for exp in range(1, 8, 2)]
+        encoder_params = DAEncoderParams(
+            column_count=10,
+            bytes_per_field_element=BYTES_PER_FIELD_ELEMENT
+        )
+        for size in sizes:
+            data = bytearray(randbytes(size*1024))
+            self.assert_encoding(encoder_params, data)