spec for posts:remap rake task

spec/tasks/posts_spec.rb

@@ -0,0 +1,17 @@
+require 'rails_helper'
+
+RSpec.describe "Post rake tasks" do
+  before do
+    Discourse::Application.load_tasks
+  end
+
+  describe 'remap' do
+    it 'should remap posts' do
+      post = Fabricate(:post, raw: "The quick brown fox jumps over the lazy dog")
+
+      Rake::Task['posts:remap'].invoke("brown","red")
+      post.reload
+      expect(post.raw).to eq('The quick red fox jumps over the lazy dog')
+    end
+  end
+end