Add BIP85 test vectors and fix implementation

src/tests/test_bip85_vectors.py

@@ -0,0 +1,39 @@
+import sys
+from pathlib import Path
+import pytest
+
+sys.path.append(str(Path(__file__).resolve().parents[1]))
+
+from local_bip85.bip85 import BIP85
+
+MASTER_XPRV = "xprv9s21ZrQH143K2LBWUUQRFXhucrQqBpKdRRxNVq2zBqsx8HVqFk2uYo8kmbaLLHRdqtQpUm98uKfu3vca1LqdGhUtyoFnCNkfmXRyPXLjbKb"
+
+EXPECTED_12 = "girl mad pet galaxy egg matter matrix prison refuse sense ordinary nose"
+
+EXPECTED_24 = "puppy ocean match cereal symbol another shed magic wrap hammer bulb intact gadget divorce twin tonight reason outdoor destroy simple truth cigar social volcano"
+
+EXPECTED_SYMM_KEY = "7040bb53104f27367f317558e78a994ada7296c6fde36a364e5baf206e502bb1"
+
+
+@pytest.fixture(scope="module")
+def bip85():
+    return BIP85(MASTER_XPRV)
+
+
+def test_bip85_mnemonic_12(bip85):
+    assert bip85.derive_mnemonic(index=0, words_num=12) == EXPECTED_12
+
+
+def test_bip85_mnemonic_24(bip85):
+    assert bip85.derive_mnemonic(index=0, words_num=24) == EXPECTED_24
+
+
+def test_bip85_symmetric_key(bip85):
+    assert bip85.derive_symmetric_key(index=0).hex() == EXPECTED_SYMM_KEY
+
+
+def test_invalid_params(bip85):
+    with pytest.raises(SystemExit):
+        bip85.derive_mnemonic(index=0, words_num=15)
+    with pytest.raises(SystemExit):
+        bip85.derive_mnemonic(index=-1, words_num=12)