Extract event signing into its own class

spec/nostr/crypto_spec.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Nostr::Crypto do
+  let(:crypto) { described_class.new }
+
+  describe '#sign_event' do
+    let(:keypair) do
+      Nostr::KeyPair.new(
+        public_key: '8a9d69c56e3c691bec8f9565e4dcbe38ae1d88fffeec3ce66b9f47558a3aa8ca',
+        private_key: '3185a47e3802f956ca5a2b4ea606c1d51c7610f239617e8f0f218d55bdf2b757'
+      )
+    end
+
+    let(:event) do
+      Nostr::Event.new(
+        kind: Nostr::EventKind::TEXT_NOTE,
+        content: 'Your feedback is appreciated, now pay $8',
+        pubkey: keypair.public_key
+      )
+    end
+
+    it 'signs an event' do
+      signed_event = crypto.sign_event(event, keypair.private_key)
+
+      aggregate_failures do
+        expect(signed_event.id.length).to eq(64)
+        expect(signed_event.sig.length).to eq(128)
+      end
+    end
+  end
+end