jobs: migrate mass updates to ActiveJob.

Also fixes a bug where mod actions weren't logged on mass updates.
Creating the mod action silently failed because it was called when
CurrentUser wasn' set.

test/jobs/tag_batch_change_job_test.rb

@@ -0,0 +1,55 @@
+require "test_helper"
+
+class TagBatchChangeJobTest < ActiveJob::TestCase
+  context "a tag batch change" do
+    setup do
+      @user = create(:moderator_user)
+      @post = create(:post, :tag_string => "aaa")
+    end
+
+    context "#estimate_update_count" do
+      should "find the correct count" do
+        assert_equal(1, TagBatchChangeJob.estimate_update_count("aaa", "bbb"))
+      end
+    end
+
+    should "execute" do
+      TagBatchChangeJob.perform_now("aaa", "bbb", @user, "127.0.0.1")
+      assert_equal("bbb", @post.reload.tag_string)
+    end
+
+    should "move saved searches" do
+      ss = create(:saved_search, user: @user, query: "123 ... 456")
+      TagBatchChangeJob.perform_now("...", "bbb", @user, "127.0.0.1")
+      assert_equal("123 456 bbb", ss.reload.normalized_query)
+    end
+
+    should "move blacklists" do
+      @user.update(blacklisted_tags: "123 456\n789\n")
+      TagBatchChangeJob.perform_now("456", "xxx", @user, "127.0.0.1")
+
+      assert_equal("123 xxx\n789", @user.reload.blacklisted_tags)
+    end
+
+    should "move only saved searches that match the mass update exactly" do
+      ss = create(:saved_search, user: @user, query: "123 ... 456")
+
+      TagBatchChangeJob.perform_now("1", "bbb", @user, "127.0.0.1")
+      assert_equal("... 123 456", ss.reload.normalized_query, "expected '123' to remain unchanged")
+
+      TagBatchChangeJob.perform_now("123 456", "789", @user, "127.0.0.1")
+      assert_equal("... 789", ss.reload.normalized_query, "expected '123 456' to be changed to '789'")
+    end
+
+    should "log a modaction" do
+      TagBatchChangeJob.perform_now("1", "2", @user, "127.0.0.1")
+      assert_equal("mass_update", ModAction.last.category)
+    end
+
+    should "raise an error if there is no predicate" do
+      assert_raises(TagBatchChangeJob::Error) do
+        TagBatchChangeJob.perform_now("", "bbb", @user, "127.0.0.1")
+      end
+    end
+  end
+end