diff --git a/spec/controllers/ajax/smile_controller_spec.rb b/spec/controllers/ajax/smile_controller_spec.rb
new file mode 100644
index 00000000..3b739f24
--- /dev/null
+++ b/spec/controllers/ajax/smile_controller_spec.rb
@@ -0,0 +1,300 @@
+# coding: utf-8
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe Ajax::SmileController, type: :controller do
+  shared_examples "returns the expected response" do
+    it "returns the expected response" do
+      expect(JSON.parse(subject.body)).to match(expected_response)
+    end
+  end
+
+  let(:user) { FactoryBot.create(:user) }
+
+  describe "#create" do
+    let(:params) do
+      {
+        id: answer_id
+      }.compact
+    end
+    let(:answer) { FactoryBot.create(:answer, user: user) }
+
+    subject { post(:create, params: params) }
+
+    context "when user is signed in" do
+      before(:each) { sign_in(user) }
+
+      context "when answer exists" do
+        let(:answer_id) { answer.id }
+        let(:expected_response) do
+          {
+            "success" => true,
+            "status" => "okay",
+            "message" => anything
+          }
+        end
+
+        it "creates a smile to the answer" do
+          expect { subject }.to(change { Smile.count }.by(1))
+          expect(answer.reload.smiles.ids).to include(Smile.last.id)
+        end
+
+        include_examples "returns the expected response"
+      end
+
+      context "when answer does not exist" do
+        let(:answer_id) { "nein!" }
+
+        let(:expected_response) do
+          {
+            "success" => false,
+            "status" => anything,
+            "message" => anything
+          }
+        end
+
+        it "does not create a smile" do
+          expect { subject }.not_to(change { Smile.count })
+        end
+
+        include_examples "returns the expected response"
+      end
+
+      context "when some parameters are missing" do
+        let(:answer_id) { nil }
+
+        let(:expected_response) do
+          {
+            "success" => false,
+            "status" => "parameter_error",
+            "message" => anything
+          }
+        end
+
+        include_examples "returns the expected response"
+      end
+    end
+
+    context "when user is not signed in" do
+      let(:answer_id) { answer.id }
+
+      let(:expected_response) do
+        {
+          "success" => false,
+          "status" => "fail",
+          "message" => anything
+        }
+      end
+
+      include_examples "returns the expected response"
+    end
+  end
+
+  describe "#destroy" do
+    let(:answer) { FactoryBot.create(:answer, user: user) }
+    let(:smile) { FactoryBot.create(:smile, user: user, answer: answer) }
+    let(:answer_id) { answer.id }
+
+    let(:params) do
+      {
+        id: answer_id
+      }
+    end
+
+    subject { delete(:destroy, params: params) }
+
+    context "when user is signed in" do
+      before(:each) { sign_in(user) }
+
+      context "when the smile exists" do
+        # ensure we already have it in the db
+        before(:each) { smile }
+
+        let(:expected_response) do
+          {
+            "success" => true,
+            "status" => "okay",
+            "message" => anything
+          }
+        end
+
+        it "deletes the smile" do
+          expect { subject }.to(change { Smile.count }.by(-1))
+        end
+
+        include_examples "returns the expected response"
+      end
+
+      context "when the smile does not exist" do
+        let(:answer_id) { "sonic_the_hedgehog" }
+
+        let(:expected_response) do
+          {
+            "success" => false,
+            "status" => anything,
+            "message" => anything
+          }
+        end
+
+        include_examples "returns the expected response"
+      end
+    end
+
+    context "when user is not signed in" do
+      let(:expected_response) do
+        {
+          "success" => false,
+          "status" => "fail",
+          "message" => anything
+        }
+      end
+
+      include_examples "returns the expected response"
+    end
+  end
+
+  describe "#create_comment" do
+    let(:params) do
+      {
+        id: comment_id
+      }.compact
+    end
+    let(:answer) { FactoryBot.create(:answer, user: user) }
+    let(:comment) { FactoryBot.create(:comment, user: user, answer: answer) }
+
+    subject { post(:create_comment, params: params) }
+
+    context "when user is signed in" do
+      before(:each) { sign_in(user) }
+
+      context "when comment exists" do
+        let(:comment_id) { comment.id }
+        let(:expected_response) do
+          {
+            "success" => true,
+            "status" => "okay",
+            "message" => anything
+          }
+        end
+
+        it "creates a smile to the comment" do
+          expect { subject }.to(change { CommentSmile.count }.by(1))
+          expect(comment.reload.smiles.ids).to include(CommentSmile.last.id)
+        end
+
+        include_examples "returns the expected response"
+      end
+
+      context "when comment does not exist" do
+        let(:comment_id) { "nein!" }
+
+        let(:expected_response) do
+          {
+            "success" => false,
+            "status" => anything,
+            "message" => anything
+          }
+        end
+
+        it "does not create a smile" do
+          expect { subject }.not_to(change { CommentSmile.count })
+        end
+
+        include_examples "returns the expected response"
+      end
+
+      context "when some parameters are missing" do
+        let(:comment_id) { nil }
+
+        let(:expected_response) do
+          {
+            "success" => false,
+            "status" => "parameter_error",
+            "message" => anything
+          }
+        end
+
+        include_examples "returns the expected response"
+      end
+    end
+
+    context "when user is not signed in" do
+      let(:comment_id) { comment.id }
+
+      let(:expected_response) do
+        {
+          "success" => false,
+          "status" => "fail",
+          "message" => anything
+        }
+      end
+
+      include_examples "returns the expected response"
+    end
+  end
+
+  describe "#destroy_comment" do
+    let(:answer) { FactoryBot.create(:answer, user: user) }
+    let(:comment) { FactoryBot.create(:comment, user: user, answer: answer) }
+    let(:comment_smile) { FactoryBot.create(:comment_smile, user: user, comment: comment) }
+    let(:comment_id) { comment.id }
+
+    let(:params) do
+      {
+        id: comment_id
+      }
+    end
+
+    subject { delete(:destroy_comment, params: params) }
+
+    context "when user is signed in" do
+      before(:each) { sign_in(user) }
+
+      context "when the smile exists" do
+        # ensure we already have it in the db
+        before(:each) { comment_smile }
+
+        let(:expected_response) do
+          {
+            "success" => true,
+            "status" => "okay",
+            "message" => anything
+          }
+        end
+
+        it "deletes the smile" do
+          expect { subject }.to(change { CommentSmile.count }.by(-1))
+        end
+
+        include_examples "returns the expected response"
+      end
+
+      context "when the smile does not exist" do
+        let(:answer_id) { "sonic_the_hedgehog" }
+
+        let(:expected_response) do
+          {
+            "success" => false,
+            "status" => anything,
+            "message" => anything
+          }
+        end
+
+        include_examples "returns the expected response"
+      end
+    end
+
+    context "when user is not signed in" do
+      let(:expected_response) do
+        {
+          "success" => false,
+          "status" => "fail",
+          "message" => anything
+        }
+      end
+
+      include_examples "returns the expected response"
+    end
+  end
+end
diff --git a/spec/factories/comment_smile.rb b/spec/factories/comment_smile.rb
new file mode 100644
index 00000000..3a2b585e
--- /dev/null
+++ b/spec/factories/comment_smile.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :comment_smile do
+    user { FactoryBot.build(:user) }
+    comment { FactoryBot.build(:comment) }
+  end
+end
diff --git a/spec/factories/smile.rb b/spec/factories/smile.rb
new file mode 100644
index 00000000..1ce23750
--- /dev/null
+++ b/spec/factories/smile.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :smile do
+    user { FactoryBot.build(:user) }
+    answer { FactoryBot.build(:answer) }
+  end
+end