diff --git a/provider/slack.go b/provider/slack.go
index bda9bb2..4d0485d 100644
--- a/provider/slack.go
+++ b/provider/slack.go
@@ -29,14 +29,18 @@ type LocatedMessage struct {
 	permalink   string
 }
 
+type HTTPClient interface {
+	Do(req *http.Request) (*http.Response, error)
+}
+
 type Slack struct {
-	client                                       *http.Client
+	client                                       HTTPClient
 	notificationRules                            []model.NotificationRule
 	reactionRules                                []model.ReactionRule
 	webhookURL, message, avatar, username, token string
 }
 
-func NewSlack(client *http.Client, notificationRules []model.NotificationRule, reactionRules []model.ReactionRule, webhookURL, token, message, avatar, username string) *Slack {
+func NewSlack(client HTTPClient, notificationRules []model.NotificationRule, reactionRules []model.ReactionRule, webhookURL, token, message, avatar, username string) *Slack {
 	return &Slack{
 		client:            client,
 		notificationRules: notificationRules,
diff --git a/provider/slack_test.go b/provider/slack_test.go
index 9285428..064782a 100644
--- a/provider/slack_test.go
+++ b/provider/slack_test.go
@@ -1,7 +1,9 @@
 package provider
 
 import (
+	"bytes"
 	"encoding/json"
+	"errors"
 	"io/ioutil"
 	"net/http"
 	"testing"
@@ -10,6 +12,18 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+type MockClient struct {
+	DoFunc func(req *http.Request) (*http.Response, error)
+}
+
+var (
+	GetDoFunc func(req *http.Request) (*http.Response, error)
+)
+
+func (m *MockClient) Do(req *http.Request) (*http.Response, error) {
+	return GetDoFunc(req)
+}
+
 func TestChannelsForMergeRequestSingleRule(t *testing.T) {
 	var mergeRequest model.MergeRequestInfo
 	var jsonString string
@@ -43,6 +57,7 @@ func TestChannelsForMergeRequestSingleRule(t *testing.T) {
 	)
 
 	assert.Equal(t, []string{"#tested"}, slack.ChannelsForMergeRequest(mergeRequest))
+	assert.Equal(t, []model.ReactionRule{{Action: "approved", Reaction: "thumbsup"}}, slack.GetReactionRules())
 }
 
 func TestChannelsForMergeRequestMultipleRules(t *testing.T) {
@@ -149,3 +164,114 @@ func TestChannelsForMergeRequestNotMatchingLabel(t *testing.T) {
 
 	assert.Equal(t, []string{}, slack.ChannelsForMergeRequest(mergeRequest))
 }
+
+func TestSearchForMessage(t *testing.T) {
+	var notifications []model.NotificationRule
+	var reactions []model.ReactionRule
+
+	json := `{"messages": {"matches": [{"channel": {"name": "channel-name", "id": "channel-id"}, "ts": "123", "permalink": "http://message-link"}]}}`
+	client := &MockClient{}
+	r := ioutil.NopCloser(bytes.NewReader([]byte(json)))
+	GetDoFunc = func(*http.Request) (*http.Response, error) {
+		return &http.Response{
+			StatusCode: 200,
+			Body:       r,
+		}, nil
+	}
+
+	slack := NewSlack(
+		client,
+		notifications,
+		reactions,
+		"https://testing.com",
+		"New MR",
+		"https://avatar",
+		"Username",
+		"Token",
+	)
+
+	locatedMessage, err := slack.search("New MergeRequest Created")
+	assert.Nil(t, err)
+	assert.Equal(t, "channel-name", locatedMessage.channelName)
+	assert.Equal(t, "channel-id", locatedMessage.channelID)
+	assert.Equal(t, "123", locatedMessage.timestamp)
+	assert.Equal(t, "http://message-link", locatedMessage.permalink)
+}
+
+func TestPostReaction(t *testing.T) {
+	var notifications []model.NotificationRule
+	var reactions []model.ReactionRule
+
+	json := `{}`
+	client := &MockClient{}
+	r := ioutil.NopCloser(bytes.NewReader([]byte(json)))
+	GetDoFunc = func(*http.Request) (*http.Response, error) {
+		return &http.Response{
+			StatusCode: 200,
+			Body:       r,
+		}, nil
+	}
+
+	slack := NewSlack(client, notifications, reactions, "https://testing.com", "New MR", "https://avatar", "Username", "Token")
+
+	locatedMessage := LocatedMessage{
+		channelID:   "channel-id",
+		channelName: "channel-name",
+		timestamp:   "123",
+		permalink:   "http://message-link",
+	}
+
+	err := slack.postReaction(locatedMessage, model.ReactionRule{Action: "approved", Reaction: "thumbsup"})
+	assert.Nil(t, err)
+}
+
+func TestPostReactionFailsWithStatusCode(t *testing.T) {
+	var notifications []model.NotificationRule
+	var reactions []model.ReactionRule
+
+	json := `{}`
+	client := &MockClient{}
+	r := ioutil.NopCloser(bytes.NewReader([]byte(json)))
+	GetDoFunc = func(*http.Request) (*http.Response, error) {
+		return &http.Response{
+			StatusCode: 404,
+			Body:       r,
+		}, nil
+	}
+
+	slack := NewSlack(client, notifications, reactions, "https://testing.com", "New MR", "https://avatar", "Username", "Token")
+
+	locatedMessage := LocatedMessage{
+		channelID:   "channel-id",
+		channelName: "channel-name",
+		timestamp:   "123",
+		permalink:   "http://message-link",
+	}
+
+	err := slack.postReaction(locatedMessage, model.ReactionRule{Action: "approved", Reaction: "thumbsup"})
+	assert.NotNil(t, err)
+	assert.ErrorContains(t, err, "response codeStatus code: 404, expected 200")
+}
+
+func TestPostReactionFailsWithClientError(t *testing.T) {
+	var notifications []model.NotificationRule
+	var reactions []model.ReactionRule
+
+	client := &MockClient{}
+	GetDoFunc = func(*http.Request) (*http.Response, error) {
+		return nil, errors.New("Error from web server")
+	}
+
+	slack := NewSlack(client, notifications, reactions, "https://testing.com", "New MR", "https://avatar", "Username", "Token")
+
+	locatedMessage := LocatedMessage{
+		channelID:   "channel-id",
+		channelName: "channel-name",
+		timestamp:   "123",
+		permalink:   "http://message-link",
+	}
+
+	err := slack.postReaction(locatedMessage, model.ReactionRule{Action: "approved", Reaction: "thumbsup"})
+	assert.NotNil(t, err)
+	assert.ErrorContains(t, err, "Error from web server")
+}