fix(tests): update error handling in SHAKE and KMAC specs

- Change expected error type from SHA3::Digest::DigestError to SHA3::Digest::Error in SHAKE tests.
- Rename TEST_VECTORS to KMAC_TEST_VECTORS for clarity and update error handling for invalid algorithms to raise ArgumentError.

Author: johanns

spec/sha3_digest_core_spec.rb

@@ -198,8 +198,8 @@
     describe 'SHAKE functionality' do
       it 'requires output length for SHAKE algorithms' do
         shake = described_class.new(:shake_128)
-        expect { shake.digest }.to raise_error(SHA3::Digest::DigestError)
-        expect { shake.hexdigest }.to raise_error(SHA3::Digest::DigestError)
+        expect { shake.digest }.to raise_error(SHA3::Digest::Error)
+        expect { shake.hexdigest }.to raise_error(SHA3::Digest::Error)
       end
 
       it 'produces variable length output for SHAKE algorithms' do
@@ -340,8 +340,8 @@
     end
 
     it 'requires output length for digest methods' do
-      expect { SHA3::Digest::SHAKE_128.new.digest }.to raise_error(SHA3::Digest::DigestError)
-      expect { SHA3::Digest::SHAKE_256.new.hexdigest }.to raise_error(SHA3::Digest::DigestError)
+      expect { SHA3::Digest::SHAKE_128.new.digest }.to raise_error(SHA3::Digest::Error)
+      expect { SHA3::Digest::SHAKE_256.new.hexdigest }.to raise_error(SHA3::Digest::Error)
     end
 
     it 'provides class methods for direct hashing' do

spec/sha3_kmac_spec.rb

@@ -6,7 +6,7 @@
   # Test vectors from NIST SP 800-185
   # https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Standards-and-Guidelines/documents/examples/KMAC_samples.pdf
 
-  TEST_VECTORS = [
+  KMAC_TEST_VECTORS = [
     {
       algorithm: :kmac_128,
       custom: '',
@@ -60,7 +60,7 @@
     end
 
     it 'raises an error for invalid algorithm' do
-      expect { described_class.new(:invalid_algo, 32, 'my key') }.to raise_error(SHA3::KMAC::KMACError)
+      expect { described_class.new(:invalid_algo, 32, 'my key') }.to raise_error(ArgumentError)
     end
 
     it 'requires the algorithm, output length, and key parameters' do
@@ -246,7 +246,7 @@
     end
   end
 
-  TEST_VECTORS.each do |vector|
+  KMAC_TEST_VECTORS.each do |vector|
     describe "test vector for #{vector[:description]}" do
       it 'produces the expected digest' do
         kmac = described_class.new(