test: add tests to cover new Exceptions in arguments.py

src/embit/descriptor/arguments.py

@@ -14,7 +14,10 @@ def __init__(self, fingerprint: bytes, derivation: list):
     @classmethod
     def from_string(cls, s: str):
         arr = s.split("/")
-        mfp = unhexlify(arr[0])
+        try:
+            mfp = unhexlify(arr[0])
+        except Exception as err:
+            raise ArgumentError(str(err))
         if len(mfp) != 4:
             raise ArgumentError("Invalid fingerprint length")
         arr[0] = "m"

src/embit/descriptor/descriptor.py

@@ -27,9 +27,25 @@ def __init__(
         # - raise if taptree is not None, but taproot=False
         if key is None and miniscript is None and taptree is None:
             raise DescriptorError("Provide a key, miniscript or taptree")
+
+        if key is not None and not isinstance(key, Key):
+            raise DescriptorError("'%s' object is not a Key" % key.__class__.__name__)
+
         if miniscript is not None:
             # will raise if can't verify
-            miniscript.verify()
+            try:
+                miniscript.verify()
+            except Exception as err:
+                raise DescriptorError(str(err))
+
+            # Chek correctness of miniscript
+            # (https://github.com/bitcoin/bips/blob/master/bip-0379.md)
+            # the top level B (base) cover the following cases:
+            # - older(n), after(n);
+            # - sha256(h), ripemd160(h), hash256(h), hash160(h);
+            # - and_b(X,Y), or_b(X,Z), or_d(X,Z);
+            # - thresh(k,X_1,...,X_n), multi(k,key_1,...,key_n), multi_a(k,key_1,...,key_n);
+            # - c:X, d:X, j:X, n:X;
             if miniscript.type != "B":
                 raise DescriptorError("Top level miniscript should be 'B'")
             # check all branches have the same length
@@ -44,10 +60,15 @@ def __init__(
         self.miniscript = miniscript
         self.wpkh = wpkh
         self.taproot = taproot
+
         self.taptree = taptree or TapTree()
+
         # make sure all keys are either taproot or not
-        for k in self.keys:
-            k.taproot = taproot
+        try:
+            for k in self.keys:
+                k.taproot = taproot
+        except Exception as err:
+            raise DescriptorError(str(err))
 
     @property
     def script_len(self):

tests/tests/test_descriptor.py

@@ -1,14 +1,62 @@
 from unittest import TestCase
 from binascii import hexlify
 from embit.descriptor import Descriptor, Key
+from embit.descriptor import miniscript
 from embit.descriptor.arguments import KeyHash, Number
 from embit.descriptor.miniscript import OPERATORS, WRAPPERS
-from embit.descriptor.errors import MiniscriptError
+from embit.descriptor.errors import ArgumentError, MiniscriptError
 from embit.descriptor.checksum import add_checksum, DescriptorError
 from embit import ec
 
 
 class DescriptorTest(TestCase):
+
+    def test_fail_initialization(self):
+        """
+        Tests the initialization of a Descriptor instance
+        initialization, where key, miniscript or taptree
+        arguments None.
+        """
+        cases = [
+            (None, None, None, "Provide a key, miniscript or taptree"),
+            ("key", None, None, "'str' object is not a Key"),
+            (None, "miniscript", None, "'str' object has no attribute 'verify'"),
+            (None, None, "taptree", "'str' object has no attribute 'keys'"),
+        ]
+
+        for case in cases:
+            with self.assertRaises(DescriptorError) as exc:
+                Descriptor(key=case[0], miniscript=case[1], taptree=case[2])
+            self.assertEqual(str(exc.exception), case[3])
+
+    def test_fail_wrong_fingerprint_length(self):
+        """Tests that a descriptor with a wrong fingerprint raises an error"""
+        cases = [
+            # A valid fingerprint for the test key is c1684a69
+            # but we use a wrong one here that is c1684a69a (9 characters instead of 8)
+            (
+                "wpkh([c1684a69a/84'/1'/0']tpubDDY2HTrz5YTJGe4dejjxgiiuex6Gfu7Ca21zEkCf7GcWpPhpM172yt9aeJqWg5zD7n6gUFfnFJeyMokc54rCQ9tWLjs9VaZHxV95g6RYjf5/1/*)#2zrpegx5",
+                "Odd-length string",
+            ),
+            # A valid fingerprint for the test key is c1684a69
+            # but we added a bytes at the end to make it invalid (a0)
+            (
+                "wpkh([c1684a69a0/84'/1'/0']tpubDDY2HTrz5YTJGe4dejjxgiiuex6Gfu7Ca21zEkCf7GcWpPhpM172yt9aeJqWg5zD7n6gUFfnFJeyMokc54rCQ9tWLjs9VaZHxV95g6RYjf5/1/*)#2zrpegx5",
+                "Invalid fingerprint length",
+            ),
+            # A valid fingerprint for the test key is c1684a69
+            # but we use a wrong one here that is c1684axj (xj characters instead of 69)
+            (
+                "wpkh([c1684axj/84'/1'/0']tpubDDY2HTrz5YTJGe4dejjxgiiuex6Gfu7Ca21zEkCf7GcWpPhpM172yt9aeJqWg5zD7n6gUFfnFJeyMokc54rCQ9tWLjs9VaZHxV95g6RYjf5/1/*)#2zrpegx5",
+                "Non-hexadecimal digit found",
+            ),
+        ]
+
+        for case in cases:
+            with self.assertRaises(ArgumentError) as exc:
+                Descriptor.from_string(case[0])
+            self.assertEqual(str(exc.exception), case[1])
+
     def test_desc_checksum(self):
         """Tests descriptor checksums"""
         desc = (

tests/tests/test_taproot.py

@@ -7,6 +7,7 @@
 from embit.psbtview import PSBTView
 from embit.ec import SchnorrSig, PublicKey
 from embit.transaction import SIGHASH
+from embit.descriptor.errors import ArgumentError
 from io import BytesIO
 from binascii import unhexlify
 
@@ -131,6 +132,15 @@ def test_invalid(self):
                 "wpkh(b4ca2da5380d9aeb5ca67e4f18c487ae9b668748517e12b788496f63765e2efa)"
             )
 
+    def test_fail_taproot_tweak(self):
+        desc = "wpkh([abcdef12/84h/22h]xpub6F6wWxm8F64iBHNhyaoh3QKCuuMUY5pfPPr1H1WuZXUXeXtZ21qjFN5ykaqnLL1jtPEFB9d94CyZrcYWKVdSiJKQ6mLGEB5sfrGFBpg6wgA/<0;1>/*)"
+        non_tr_desc = Descriptor.from_string(desc)
+        key = non_tr_desc.keys[0]
+        with self.assertRaises(Exception) as exc:
+            assert not getattr(key, "taproot", False)
+            key.taproot_tweak()
+        self.assertEqual(str(exc.exception), "Key is not taproot")
+
     def test_sign_verify(self):
         unsigned = PSBT.from_string(B64PSBT)
         signed = PSBT.from_string(B64SIGNED)