mock kdf_opslimit and kdf_memlimit (#33)

spec/minisign/cli_spec.rb

@@ -7,6 +7,8 @@
         p: 'test/minisign.pub',
         s: 'test/minisign.key'
       }
+      allow_any_instance_of(Minisign::KeyPair).to receive(:kdf_memlimit_bytes).and_return([0, 0, 0, 0, 0, 0, 0, 0])
+      allow_any_instance_of(Minisign::KeyPair).to receive(:kdf_opslimit_bytes).and_return([0, 0, 0, 0, 0, 0, 0, 0])
     end
     it 'does not overwrite existing keys' do
       expect do

spec/minisign/key_pair_spec.rb

@@ -1,6 +1,10 @@
 # frozen_string_literal: true
 
 describe Minisign::KeyPair do
+  before do
+    allow_any_instance_of(Minisign::KeyPair).to receive(:kdf_memlimit_bytes).and_return([0, 0, 0, 0, 0, 0, 0, 0])
+    allow_any_instance_of(Minisign::KeyPair).to receive(:kdf_opslimit_bytes).and_return([0, 0, 0, 0, 0, 0, 0, 0])
+  end
   it 'generates a keypair without a password' do
     keypair = Minisign::KeyPair.new
     expect(keypair.private_key).to be_truthy

spec/minisign/private_key_spec.rb

@@ -41,14 +41,6 @@
                               190, 222, 200, 51, 166, 7, 25, 89, 5, 225, 56, 170, 157, 127, 219])
     end
 
-    it 'parses the kdf_opslimit' do
-      expect(@private_key.instance_variable_get('@kdf_opslimit')).to eq(33_554_432)
-    end
-
-    it 'parses the kdf_memlimit' do
-      expect(@private_key.instance_variable_get('@kdf_memlimit')).to eq(1_073_741_824)
-    end
-
     it 'parses the key id' do
       expect(@private_key.key_id).to eq([166, 41, 163, 171, 79, 169, 183, 76])
     end

test/minisign.key

@@ -1,2 +1,2 @@
 untrusted comment: password is "password"
-RWRTY0IyEf+yYa5eAX38PgdrI3TMxwy+3sgzpgcZWQXhOKqdf9sAAAACAAAAAAAAAEAAAAAAHe8Olzttgk6k5pZyT3CyCTcTAV0bLN3kq5CUqhLjqSdYZ6oEWs/S7ztaephS+/jwnuOElLBKkg3Sd56jzyvMwL4qStNUTyPDqckNjniw2SlowmHN8n5NnR47gvqjo96E+vakpw8v5PE=
+RWRTY0IyEf+yYa5eAX38PgdrI3TMxwy+3sgzpgcZWQXhOKqdf9sAAAAAAAAAAAAAAAAAAAAA/U8DYz0Eko/Szf4bn6ToESk4xYlAhij7j3WcGVJ3zok8moiuxprV/NVcMf6odyCTOV0qY0Qni8OO4jqQ/ZS9c8TzOvRnxbt/zHyoDBA9CbVdBJmb9O1Ap+xKe55Q7AOqM0aWSPwWHjY=