Add spec for on_conflict reject

spec/support/workers/until_and_while_executing_reject_job.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+# :nocov:
+
+class UntilAndWhileExecutingRejectJob
+  include Sidekiq::Worker
+
+  sidekiq_options lock: :until_and_while_executing,
+                  queue: :working,
+                  on_conflict: {
+                    client: :reject,
+                    server: :reject,
+                  }
+
+  def self.lock_args(args)
+    [args[0]]
+  end
+
+  def perform(key); end
+end

spec/workers/until_and_while_executing_reject_job_spec.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+RSpec.describe UntilAndWhileExecutingRejectJob do
+  it_behaves_like "sidekiq with options" do
+    let(:options) do
+      {
+        "queue" => :working,
+        "retry" => true,
+        "lock" => :until_and_while_executing,
+        "on_conflict" => { client: :reject, server: :reject },
+      }
+    end
+  end
+
+  it "rejects the job successfully" do
+    Sidekiq::Testing.disable! do
+      set = Sidekiq::ScheduledSet.new
+
+      described_class.perform_at(Time.now + 30, 1)
+      expect(set.size).to eq(1)
+
+      expect(described_class.perform_at(Time.now + 30, 1)).to be_nil
+
+      set.each(&:delete)
+    end
+  end
+
+  it "rejects job successfully when using perform_in" do
+    Sidekiq::Testing.disable! do
+      set = Sidekiq::ScheduledSet.new
+
+      described_class.perform_in(30, 1)
+      expect(set.size).to eq(1)
+
+      expect(described_class.perform_in(30, 1)).to be_nil
+
+      set.each(&:delete)
+    end
+  end
+end