Add a test case for preregistering with different data

We want to make sure that if preregister is called with different data,
that the postponed job table is updated.

ext/-test-/postponed_job/postponed_job.c

@@ -176,6 +176,42 @@ pjob_preregister_multiple_times(VALUE self)
 
 }
 
+struct pjob_append_data_args {
+    VALUE ary;
+    VALUE data;
+};
+
+static void
+pjob_append_data_callback(void *vctx) {
+    struct pjob_append_data_args *ctx = (struct pjob_append_data_args *)vctx;
+    Check_Type(ctx->ary, T_ARRAY);
+    rb_ary_push(ctx->ary, ctx->data);
+}
+
+static VALUE
+pjob_preregister_calls_with_last_argument(VALUE self)
+{
+    VALUE ary = rb_ary_new();
+
+    struct pjob_append_data_args arg1 = { .ary = ary, .data = INT2FIX(1) };
+    struct pjob_append_data_args arg2 = { .ary = ary, .data = INT2FIX(2) };
+    struct pjob_append_data_args arg3 = { .ary = ary, .data = INT2FIX(3) };
+    struct pjob_append_data_args arg4 = { .ary = ary, .data = INT2FIX(4) };
+
+    rb_postponed_job_handle_t h;
+    h = rb_postponed_job_preregister(0, pjob_append_data_callback, &arg1);
+    rb_postponed_job_preregister(0, pjob_append_data_callback, &arg2);
+    rb_postponed_job_trigger(h);
+    rb_postponed_job_preregister(0, pjob_append_data_callback, &arg3);
+    rb_thread_sleep(0); // should execute with arg3
+
+    rb_postponed_job_preregister(0, pjob_append_data_callback, &arg4);
+    rb_postponed_job_trigger(h);
+    rb_thread_sleep(0); // should execute with arg4
+
+    return ary;
+}
+
 void
 Init_postponed_job(VALUE self)
 {
@@ -190,5 +226,6 @@ Init_postponed_job(VALUE self)
     rb_define_module_function(mBug, "postponed_job_preregister_and_call_with_sleep", pjob_preregister_and_call_with_sleep, 1);
     rb_define_module_function(mBug, "postponed_job_preregister_and_call_without_sleep", pjob_preregister_and_call_without_sleep, 1);
     rb_define_module_function(mBug, "postponed_job_preregister_multiple_times", pjob_preregister_multiple_times, 0);
+    rb_define_module_function(mBug, "postponed_job_preregister_calls_with_last_argument", pjob_preregister_calls_with_last_argument, 0);
 }
 

test/-ext-/postponed_job/test_postponed_job.rb

@@ -25,6 +25,14 @@ class TestPostponed_job < Test::Unit::TestCase
     RUBY
   end
 
+  def test_multiple_preregistration_with_new_data
+    assert_separately([], __FILE__, __LINE__, <<-'RUBY')
+      require '-test-/postponed_job'
+      values = Bug.postponed_job_preregister_calls_with_last_argument
+      # i.e. the callback is called with the last argument it was preregistered with
+      assert_equal [3, 4], values
+    RUBY
+  end
 
   def test_legacy_register
     assert_separately([], __FILE__, __LINE__, <<-'RUBY')