diff --git a/app/models/post_analyzer.rb b/app/models/post_analyzer.rb
index 5431a16ce38..29790bcaf92 100644
--- a/app/models/post_analyzer.rb
+++ b/app/models/post_analyzer.rb
@@ -20,7 +20,8 @@ class PostAnalyzer
     # wait for the post processor.
     dirty = false
     result = Oneboxer.apply(cooked) do |url, elem|
-      Oneboxer.render_from_cache(url)
+      Oneboxer.invalidate(url) if args.last[:invalidate_oneboxes]
+      Oneboxer.onebox url
     end
 
     cooked = result.to_html if result.changed?
diff --git a/spec/models/post_analyzer_spec.rb b/spec/models/post_analyzer_spec.rb
index 8b161c01682..22ed5eba86a 100644
--- a/spec/models/post_analyzer_spec.rb
+++ b/spec/models/post_analyzer_spec.rb
@@ -2,10 +2,39 @@ require 'spec_helper'
 
 describe PostAnalyzer do
 
-  let(:topic) { Fabricate(:topic) }
-  let(:default_topic_id) { topic.id }
-  let(:post_args) do
-    {user: topic.user, topic: topic}
+  let(:default_topic_id) { 12 }
+
+  describe '#cook' do
+    let(:post_analyzer) { described_class.new nil, nil  }
+
+    let(:args) { [raw, options] }
+    let(:raw) { "Here's a tweet:\n#{url}" }
+    let(:options) { {} }
+
+    let(:url) {
+      'https://twitter.com/evil_trout/status/345954894420787200'
+    }
+
+    before { Oneboxer.stubs(:onebox) }
+
+    it 'fetches the onebox for any urls in the post' do
+      Oneboxer.expects(:onebox).with url
+      post_analyzer.cook(*args)
+    end
+
+    it 'does not invalidate the onebox cache' do
+      Oneboxer.expects(:invalidate).with(url).never
+      post_analyzer.cook(*args)
+    end
+
+    context 'when invalidating oneboxes' do
+      let(:options) {{ invalidate_oneboxes: true }}
+
+      it 'invalidates the oneboxes for urls in the post' do
+        Oneboxer.expects(:invalidate).with url
+        post_analyzer.cook(*args)
+      end
+    end
   end
 
   context "links" do
@@ -115,6 +144,7 @@ describe PostAnalyzer do
     end
 
     it "finds links from markdown" do
+      Oneboxer.stubs :onebox
       post_analyzer = PostAnalyzer.new(raw_post_one_link_md, default_topic_id)
       post_analyzer.link_count.should == 1
     end
diff --git a/spec/models/post_spec.rb b/spec/models/post_spec.rb
index 2a8b5dd3fed..bd2bc0411cb 100644
--- a/spec/models/post_spec.rb
+++ b/spec/models/post_spec.rb
@@ -2,6 +2,8 @@ require 'spec_helper'
 require_dependency 'post_destroyer'
 
 describe Post do
+  before { Oneboxer.stubs :onebox }
+
   # Help us build a post with a raw body
   def post_with_body(body, user=nil)
     args = post_args.merge(raw: body)