diff --git a/spec/lib/appsignal/event_formatter/mongo_ruby_driver/query_formatter_spec.rb b/spec/lib/appsignal/event_formatter/mongo_ruby_driver/query_formatter_spec.rb
index 82c0f3105..8bae4ef5f 100644
--- a/spec/lib/appsignal/event_formatter/mongo_ruby_driver/query_formatter_spec.rb
+++ b/spec/lib/appsignal/event_formatter/mongo_ruby_driver/query_formatter_spec.rb
@@ -11,8 +11,12 @@
     end
 
     it "should apply a strategy for each key" do
+      # TODO: additional curly brackets required for issue
+      # https://github.com/rspec/rspec-mocks/issues/1460
+      # rubocop:disable Style/BracesAroundHashParameters
       expect(formatter).to receive(:apply_strategy)
-        .with(:sanitize_document, "_id" => 1)
+        .with(:sanitize_document, { "_id" => 1 })
+      # rubocop:enable Style/BracesAroundHashParameters
 
       expect(formatter).to receive(:apply_strategy)
         .with(:allow, "users")
diff --git a/spec/lib/appsignal/integrations/mongo_ruby_driver_spec.rb b/spec/lib/appsignal/integrations/mongo_ruby_driver_spec.rb
index e00621fa4..e4ff24b7a 100644
--- a/spec/lib/appsignal/integrations/mongo_ruby_driver_spec.rb
+++ b/spec/lib/appsignal/integrations/mongo_ruby_driver_spec.rb
@@ -17,8 +17,12 @@
       end
 
       it "should sanitize command" do
+        # TODO: additional curly brackets required for issue
+        # https://github.com/rspec/rspec-mocks/issues/1460
+        # rubocop:disable Style/BracesAroundHashParameters
         expect(Appsignal::EventFormatter::MongoRubyDriver::QueryFormatter)
-          .to receive(:format).with("find", "foo" => "bar")
+          .to receive(:format).with("find", { "foo" => "bar" })
+        # rubocop:enable Style/BracesAroundHashParameters
 
         subscriber.started(event)
       end
diff --git a/spec/lib/appsignal/integrations/sidekiq_spec.rb b/spec/lib/appsignal/integrations/sidekiq_spec.rb
index 7a8e445e5..00a9b1386 100644
--- a/spec/lib/appsignal/integrations/sidekiq_spec.rb
+++ b/spec/lib/appsignal/integrations/sidekiq_spec.rb
@@ -228,10 +228,14 @@ class DelayedTestClass; end
     let(:error) { ExampleException }
 
     it "creates a transaction and adds the error" do
+      # TODO: additional curly brackets required for issue
+      # https://github.com/rspec/rspec-mocks/issues/1460
+      # rubocop:disable Style/BracesAroundHashParameters
       expect(Appsignal).to receive(:increment_counter)
-        .with("sidekiq_queue_job_count", 1, :queue => "default", :status => :failed)
+        .with("sidekiq_queue_job_count", 1, { :queue => "default", :status => :failed })
       expect(Appsignal).to receive(:increment_counter)
-        .with("sidekiq_queue_job_count", 1, :queue => "default", :status => :processed)
+        .with("sidekiq_queue_job_count", 1, { :queue => "default", :status => :processed })
+      # rubocop:enable Style/BracesAroundHashParameters
 
       expect do
         perform_job { raise error, "uh oh" }
@@ -267,8 +271,12 @@ class DelayedTestClass; end
 
   context "without an error" do
     it "creates a transaction with events" do
+      # TODO: additional curly brackets required for issue
+      # https://github.com/rspec/rspec-mocks/issues/1460
+      # rubocop:disable Style/BracesAroundHashParameters
       expect(Appsignal).to receive(:increment_counter)
-        .with("sidekiq_queue_job_count", 1, :queue => "default", :status => :processed)
+        .with("sidekiq_queue_job_count", 1, { :queue => "default", :status => :processed })
+      # rubocop:enable Style/BracesAroundHashParameters
 
       perform_job
 
diff --git a/spec/lib/appsignal_spec.rb b/spec/lib/appsignal_spec.rb
index 30ca29922..88a6c88ea 100644
--- a/spec/lib/appsignal_spec.rb
+++ b/spec/lib/appsignal_spec.rb
@@ -427,49 +427,89 @@
     end
 
     describe ".monitor_single_transaction" do
+      around { |example| keep_transactions { example.run } }
+
       context "with a successful call" do
-        it "should call monitor_transaction and stop" do
-          expect(Appsignal).to receive(:monitor_transaction).with(
-            "perform_job.something",
-            :key => :value
-          ).and_yield
+        it "calls monitor_transaction and Appsignal.stop" do
           expect(Appsignal).to receive(:stop)
 
-          Appsignal.monitor_single_transaction("perform_job.something", :key => :value) do
+          Appsignal.monitor_single_transaction(
+            "perform_job.something",
+            :controller => :my_controller,
+            :action => :my_action
+          ) do
             # nothing
           end
+
+          transaction = last_transaction
+          transaction_hash = transaction.to_h
+          expect(transaction_hash).to include(
+            "action" => "my_controller#my_action"
+          )
+          expect(transaction_hash["events"]).to match([
+            hash_including(
+              "name" => "perform_job.something",
+              "title" => "",
+              "body" => "",
+              "body_format" => Appsignal::EventFormatter::DEFAULT
+            )
+          ])
         end
       end
 
       context "with an erroring call" do
         let(:error) { ExampleException.new }
 
-        it "should call monitor_transaction and stop and then raise the error" do
-          expect(Appsignal).to receive(:monitor_transaction).with(
-            "perform_job.something",
-            :key => :value
-          ).and_yield
+        it "calls monitor_transaction and stop and re-raises the error" do
           expect(Appsignal).to receive(:stop)
 
           expect do
-            Appsignal.monitor_single_transaction("perform_job.something", :key => :value) do
+            Appsignal.monitor_single_transaction(
+              "perform_job.something",
+              :controller => :my_controller,
+              :action => :my_action
+            ) do
               raise error
             end
           end.to raise_error(error)
+
+          transaction = last_transaction
+          transaction_hash = transaction.to_h
+          expect(transaction_hash).to include(
+            "action" => "my_controller#my_action"
+          )
+          expect(transaction_hash["events"]).to match([
+            hash_including(
+              "name" => "perform_job.something",
+              "title" => "",
+              "body" => "",
+              "body_format" => Appsignal::EventFormatter::DEFAULT
+            )
+          ])
         end
       end
     end
 
     describe ".tag_request" do
-      before { allow(Appsignal::Transaction).to receive(:current).and_return(transaction) }
+      let(:transaction) { http_request_transaction }
+      around do |example|
+        start_agent
+        with_current_transaction transaction do
+          keep_transactions { example.run }
+        end
+      end
 
       context "with transaction" do
-        let(:transaction) { double }
-        it "should call set_tags on transaction" do
-          expect(transaction).to receive(:set_tags).with("a" => "b")
-        end
+        it "calls set_tags on the current transaction" do
+          Appsignal.tag_request("a" => "b")
+          transaction.complete # Manually trigger transaction sampling
 
-        after { Appsignal.tag_request("a" => "b") }
+          expect(transaction.to_h).to include(
+            "sample_data" => hash_including(
+              "tags" => { "a" => "b" }
+            )
+          )
+        end
       end
 
       context "without transaction" do
diff --git a/spec/support/helpers/transaction_helpers.rb b/spec/support/helpers/transaction_helpers.rb
index f5cf20948..85e10284c 100644
--- a/spec/support/helpers/transaction_helpers.rb
+++ b/spec/support/helpers/transaction_helpers.rb
@@ -56,6 +56,16 @@ def clear_current_transaction!
     Thread.current[:appsignal_transaction] = nil
   end
 
+  # Set the current for the duration of the given block.
+  #
+  # Helper for {set_current_transaction} and {clear_current_transaction!}
+  def with_current_transaction(transaction)
+    set_current_transaction transaction
+    yield
+  ensure
+    clear_current_transaction!
+  end
+
   # Track the AppSignal transaction JSON when a transaction gets completed
   # ({Appsignal::Transaction.complete}).
   #