Raise exception when required cryptography dependency is missing (#963)

* Raise exception when required cryptography dependency is missing

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Add tests for `MissingCryptographyError`

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

jwt/api_jwk.py

@@ -5,7 +5,13 @@
 from typing import Any
 
 from .algorithms import get_default_algorithms, has_crypto, requires_cryptography
-from .exceptions import InvalidKeyError, PyJWKError, PyJWKSetError, PyJWTError
+from .exceptions import (
+    InvalidKeyError,
+    MissingCryptographyError,
+    PyJWKError,
+    PyJWKSetError,
+    PyJWTError,
+)
 from .types import JWKDict
 
 
@@ -50,7 +56,9 @@ def __init__(self, jwk_data: JWKDict, algorithm: str | None = None) -> None:
                 raise InvalidKeyError(f"Unsupported kty: {kty}")
 
         if not has_crypto and algorithm in requires_cryptography:
-            raise PyJWKError(f"{algorithm} requires 'cryptography' to be installed.")
+            raise MissingCryptographyError(
+                f"{algorithm} requires 'cryptography' to be installed."
+            )
 
         self.algorithm_name = algorithm
 
@@ -96,7 +104,9 @@ def __init__(self, keys: list[JWKDict]) -> None:
         for key in keys:
             try:
                 self.keys.append(PyJWK(key))
-            except PyJWTError:
+            except PyJWTError as error:
+                if isinstance(error, MissingCryptographyError):
+                    raise error
                 # skip unusable keys
                 continue
 

jwt/exceptions.py

@@ -58,6 +58,10 @@ class PyJWKError(PyJWTError):
     pass
 
 
+class MissingCryptographyError(PyJWKError):
+    pass
+
+
 class PyJWKSetError(PyJWTError):
     pass
 

tests/test_api_jwk.py

@@ -4,7 +4,12 @@
 
 from jwt.algorithms import has_crypto
 from jwt.api_jwk import PyJWK, PyJWKSet
-from jwt.exceptions import InvalidKeyError, PyJWKError, PyJWKSetError
+from jwt.exceptions import (
+    InvalidKeyError,
+    MissingCryptographyError,
+    PyJWKError,
+    PyJWKSetError,
+)
 
 from .utils import crypto_required, key_path, no_crypto_required
 
@@ -212,9 +217,14 @@ def test_missing_crypto_library_good_error_message(self):
             PyJWK({"kty": "dummy"}, algorithm="RS256")
             assert "cryptography" in str(exc.value)
 
+    @no_crypto_required
+    def test_missing_crypto_library_raises_missing_cryptography_error(self):
+        with pytest.raises(MissingCryptographyError):
+            PyJWK({"kty": "dummy"}, algorithm="RS256")
+
 
-@crypto_required
 class TestPyJWKSet:
+    @crypto_required
     def test_should_load_keys_from_jwk_data_dict(self):
         algo = RSAAlgorithm(RSAAlgorithm.SHA256)
 
@@ -236,6 +246,7 @@ def test_should_load_keys_from_jwk_data_dict(self):
         assert jwk.key_id == "keyid-abc123"
         assert jwk.public_key_use == "sig"
 
+    @crypto_required
     def test_should_load_keys_from_jwk_data_json_string(self):
         algo = RSAAlgorithm(RSAAlgorithm.SHA256)
 
@@ -257,6 +268,7 @@ def test_should_load_keys_from_jwk_data_json_string(self):
         assert jwk.key_id == "keyid-abc123"
         assert jwk.public_key_use == "sig"
 
+    @crypto_required
     def test_keyset_should_index_by_kid(self):
         algo = RSAAlgorithm(RSAAlgorithm.SHA256)
 
@@ -279,6 +291,7 @@ def test_keyset_should_index_by_kid(self):
         with pytest.raises(KeyError):
             _ = jwk_set["this-kid-does-not-exist"]
 
+    @crypto_required
     def test_keyset_with_unknown_alg(self):
         # first keyset with unusable key and usable key
         with open(key_path("jwk_keyset_with_unknown_alg.json")) as keyfile:
@@ -296,12 +309,19 @@ def test_keyset_with_unknown_alg(self):
             with pytest.raises(PyJWKSetError):
                 _ = PyJWKSet.from_json(jwks_text)
 
+    @crypto_required
     def test_invalid_keys_list(self):
         with pytest.raises(PyJWKSetError) as err:
             PyJWKSet(keys="string")  # type: ignore
         assert str(err.value) == "Invalid JWK Set value"
 
+    @crypto_required
     def test_empty_keys_list(self):
         with pytest.raises(PyJWKSetError) as err:
             PyJWKSet(keys=[])
         assert str(err.value) == "The JWK Set did not contain any keys"
+
+    @no_crypto_required
+    def test_missing_crypto_library_raises_when_required(self):
+        with pytest.raises(MissingCryptographyError):
+            PyJWKSet(keys=[{"kty": "RSA"}])