diff --git a/spec/services/comment_service_spec.rb b/spec/services/comment_service_spec.rb
new file mode 100644
index 000000000..947fa89e5
--- /dev/null
+++ b/spec/services/comment_service_spec.rb
@@ -0,0 +1,102 @@
+require "spec_helper"
+
+describe CommentService do
+  let(:post) { alice.post(:status_message, text: "hello", to: alice.aspects.first) }
+
+  describe "#create" do
+    it "creates a comment on my own post" do
+      comment = CommentService.new(alice).create(post.id, "hi")
+      expect(comment.text).to eq("hi")
+    end
+
+    it "creates a comment on post of a contact" do
+      comment = CommentService.new(bob).create(post.id, "hi")
+      expect(comment.text).to eq("hi")
+    end
+
+    it "attaches the comment to the post" do
+      comment = CommentService.new(alice).create(post.id, "hi")
+      expect(post.comments.first.text).to eq("hi")
+      expect(post.comments.first.id).to eq(comment.id)
+    end
+
+    it "fail if the post does not exist" do
+      expect {
+        CommentService.new(alice).create("unknown id", "hi")
+      }.to raise_error ActiveRecord::RecordNotFound
+    end
+
+    it "fail if the user can not see the post" do
+      expect {
+        CommentService.new(eve).create("unknown id", "hi")
+      }.to raise_error ActiveRecord::RecordNotFound
+    end
+  end
+
+  describe "#destroy" do
+    let(:comment) { CommentService.new(bob).create(post.id, "hi") }
+
+    it "lets the user destroy his own comment" do
+      result = CommentService.new(bob).destroy(comment.id)
+      expect(result).to be_truthy
+    end
+
+    it "lets the parent author destroy others comment" do
+      result = CommentService.new(alice).destroy(comment.id)
+      expect(result).to be_truthy
+    end
+
+    it "does not let someone destroy others comment" do
+      result = CommentService.new(eve).destroy(comment.id)
+      expect(result).to be_falsey
+    end
+
+    it "fails if the comment does not exist" do
+      expect {
+        CommentService.new(bob).destroy("unknown id")
+      }.to raise_error ActiveRecord::RecordNotFound
+    end
+  end
+
+  describe "#find_for_post" do
+    context "with user" do
+      it "returns comments for a public post" do
+        post = alice.post(:status_message, text: "hello", public: true)
+        comment = CommentService.new(alice).create(post.id, "hi")
+        expect(CommentService.new(eve).find_for_post(post.id)).to include(comment)
+      end
+
+      it "returns comments for a visible private post" do
+        comment = CommentService.new(alice).create(post.id, "hi")
+        expect(CommentService.new(bob).find_for_post(post.id)).to include(comment)
+      end
+
+      it "does not return comments for private post the user can not see" do
+        expect {
+          CommentService.new(eve).find_for_post(post.id)
+        }.to raise_error ActiveRecord::RecordNotFound
+      end
+    end
+
+    context "without user" do
+      it "returns comments for a public post" do
+        post = alice.post(:status_message, text: "hello", public: true)
+        comment = CommentService.new(alice).create(post.id, "hi")
+        expect(CommentService.new.find_for_post(post.id)).to include(comment)
+      end
+
+      it "does not return comments for private post" do
+        expect {
+          CommentService.new.find_for_post(post.id)
+        }.to raise_error ActiveRecord::RecordNotFound
+      end
+    end
+
+    it "returns all comments of a post" do
+      post = alice.post(:status_message, text: "hello", public: true)
+      comments = [alice, bob, eve].map {|user| CommentService.new(user).create(post.id, "hi") }
+
+      expect(CommentService.new.find_for_post(post.id)).to eq(comments)
+    end
+  end
+end