Verify ActiveJob job signature matches arguments

Guards against false-positives where both the implementation
and have_enqueued_job or have_been_enqueued matchers are passed
the wrong arguments which don't match the job's signature.

Prior to this change it was possible for the implmentation and
spec to pass whilst expecting the wrong number of arguments,
or mixing up the positional/keyword arguments. This resulted
in a passing test and the implementation failing at runtime.

Author: odlp

lib/rspec/rails/matchers/active_job.rb

@@ -103,6 +103,7 @@ def check(jobs)
             @matching_jobs, @unmatching_jobs = jobs.partition do |job|
               if job_match?(job) && arguments_match?(job) && queue_match?(job) && at_match?(job)
                 args = deserialize_arguments(job)
+                verify_arguments_match_signature!(job, args)
                 @block.call(*args)
                 true
               else
@@ -152,6 +153,18 @@ def arguments_match?(job)
             end
           end
 
+          def verify_arguments_match_signature!(job, args)
+            job_method = job.fetch(:job).public_instance_method(:perform)
+            verify_signature!(job_method, args)
+          end
+
+          def verify_signature!(job_method, args)
+            signature = Support::MethodSignature.new(job_method)
+            verifier = Support::StrictSignatureVerifier.new(signature, args)
+
+            raise ArgumentError, verifier.error_message unless verifier.valid?
+          end
+
           def queue_match?(job)
             return true unless @queue
 

lib/rspec/rails/matchers/have_enqueued_mail.rb

@@ -89,6 +89,10 @@ def arguments_match?(job)
           super(job)
         end
 
+        def verify_arguments_match_signature!(_job, _args)
+          # Not implemented for mailers
+        end
+
         def base_mailer_args
           [mailer_class_name, @method_name.to_s, MAILER_JOB_METHOD]
         end

spec/rspec/rails/matchers/active_job_spec.rb

@@ -64,6 +64,20 @@ def self.name; "LoggingJob"; end
     end
   end
 
+  let(:two_args_job) do
+    Class.new(ActiveJob::Base) do
+      def perform(one, two); end
+      def self.name; "TwoArgsJob"; end
+    end
+  end
+
+  let(:keyword_args_job) do
+    Class.new(ActiveJob::Base) do
+      def perform(one:, two:); end
+      def self.name; "KeywordArgsJob"; end
+    end
+  end
+
   before do
     ActiveJob::Base.queue_adapter = :test
   end
@@ -324,6 +338,22 @@ def perform; raise StandardError; end
       }.to have_enqueued_job.with(42, "David")
     end
 
+    it "fails if the arguments do not match the job's signature" do
+      expect {
+        expect {
+          two_args_job.perform_later(1)
+        }.to have_enqueued_job.with(1)
+      }.to raise_error(ArgumentError, /Wrong number of arguments/)
+    end
+
+    it "fails if the job's signature/arguments are mismatched keyword/positional arguments" do
+      expect {
+        expect {
+          keyword_args_job.perform_later(1, 2)
+        }.to have_enqueued_job.with(1, 2)
+      }.to raise_error(ArgumentError, /Missing required keyword arguments/)
+    end
+
     it "passes with provided arguments containing global id object" do
       global_id_object = GlobalIdModel.new("42")
 
@@ -457,6 +487,22 @@ def perform; raise StandardError; end
       }.to raise_error(/expected to enqueue exactly 1 jobs, but enqueued 0/)
     end
 
+    it "fails if the arguments do not match the job's signature" do
+      two_args_job.perform_later(1)
+
+      expect {
+        expect(two_args_job).to have_been_enqueued.with(1)
+      }.to raise_error(ArgumentError, /Wrong number of arguments/)
+    end
+
+    it "fails if the job's signature/arguments are mismatched keyword/positional arguments" do
+      keyword_args_job.perform_later(1, 2)
+
+      expect {
+        expect(keyword_args_job).to have_been_enqueued.with(1, 2)
+      }.to raise_error(ArgumentError, /Missing required keyword arguments/)
+    end
+
     it "fails when negated and several jobs enqueued" do
       heavy_lifting_job.perform_later
       heavy_lifting_job.perform_later