Add test for unpin use case

spec/lib/use_case/answer/unpin_spec.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe UseCase::Answer::Unpin do
+  include ActiveSupport::Testing::TimeHelpers
+
+  subject { UseCase::Answer::Unpin.call(user:, answer:) }
+
+  context "answer exists" do
+    let(:pinned_at) { Time.at(1603290950).utc }
+    let(:answer) { FactoryBot.create(:answer, user: FactoryBot.create(:user), pinned_at:) }
+
+    context "as answer owner" do
+      let(:user) { answer.user }
+
+      it "unpins the answer" do
+        expect { subject }.to change { answer.pinned_at }.from(pinned_at).to(nil)
+      end
+    end
+
+    context "as other user" do
+      let(:user) { FactoryBot.create(:user) }
+
+      it "does not unpin the answer" do
+        expect { subject }.to raise_error(Errors::NotAuthorized)
+        expect(answer.reload.pinned_at).to eq(pinned_at)
+      end
+    end
+  end
+end