diff --git a/models/issue_reaction.go b/models/issue_reaction.go
index 358e0701b3..3ecf536420 100644
--- a/models/issue_reaction.go
+++ b/models/issue_reaction.go
@@ -9,10 +9,10 @@ import (
 	"fmt"
 	"time"
 
+	"code.gitea.io/gitea/modules/setting"
+
 	"github.com/go-xorm/builder"
 	"github.com/go-xorm/xorm"
-
-	"code.gitea.io/gitea/modules/setting"
 )
 
 // Reaction represents a reactions on issues and comments.
diff --git a/models/issue_reaction_test.go b/models/issue_reaction_test.go
new file mode 100644
index 0000000000..8363e534d5
--- /dev/null
+++ b/models/issue_reaction_test.go
@@ -0,0 +1,166 @@
+// Copyright 2017 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+package models
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func addReaction(t *testing.T, doer *User, issue *Issue, comment *Comment, content string) {
+	var reaction *Reaction
+	var err error
+	if comment == nil {
+		reaction, err = CreateIssueReaction(doer, issue, content)
+	} else {
+		reaction, err = CreateCommentReaction(doer, issue, comment, content)
+	}
+	assert.NoError(t, err)
+	assert.NotNil(t, reaction)
+}
+
+func TestIssueAddReaction(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	user1 := AssertExistsAndLoadBean(t, &User{ID: 1}).(*User)
+
+	issue1 := AssertExistsAndLoadBean(t, &Issue{ID: 1}).(*Issue)
+
+	addReaction(t, user1, issue1, nil, "heart")
+
+	AssertExistsAndLoadBean(t, &Reaction{Type: "heart", UserID: user1.ID, IssueID: issue1.ID})
+}
+
+func TestIssueAddDuplicateReaction(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	user1 := AssertExistsAndLoadBean(t, &User{ID: 1}).(*User)
+
+	issue1 := AssertExistsAndLoadBean(t, &Issue{ID: 1}).(*Issue)
+
+	addReaction(t, user1, issue1, nil, "heart")
+
+	reaction, err := CreateReaction(&ReactionOptions{
+		Doer:  user1,
+		Issue: issue1,
+		Type:  "heart",
+	})
+	assert.Error(t, err)
+	assert.Nil(t, reaction)
+
+	AssertExistsAndLoadBean(t, &Reaction{Type: "heart", UserID: user1.ID, IssueID: issue1.ID})
+}
+
+func TestIssueDeleteReaction(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	user1 := AssertExistsAndLoadBean(t, &User{ID: 1}).(*User)
+
+	issue1 := AssertExistsAndLoadBean(t, &Issue{ID: 1}).(*Issue)
+
+	addReaction(t, user1, issue1, nil, "heart")
+
+	err := DeleteIssueReaction(user1, issue1, "heart")
+	assert.NoError(t, err)
+
+	AssertNotExistsBean(t, &Reaction{Type: "heart", UserID: user1.ID, IssueID: issue1.ID})
+}
+
+func TestIssueReactionCount(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	setting.UI.ReactionMaxUserNum = 2
+
+	user1 := AssertExistsAndLoadBean(t, &User{ID: 1}).(*User)
+	user2 := AssertExistsAndLoadBean(t, &User{ID: 2}).(*User)
+	user3 := AssertExistsAndLoadBean(t, &User{ID: 3}).(*User)
+	user4 := AssertExistsAndLoadBean(t, &User{ID: 4}).(*User)
+	ghost := NewGhostUser()
+
+	issue1 := AssertExistsAndLoadBean(t, &Issue{ID: 1}).(*Issue)
+
+	addReaction(t, user1, issue1, nil, "heart")
+	addReaction(t, user2, issue1, nil, "heart")
+	addReaction(t, user3, issue1, nil, "heart")
+	addReaction(t, user3, issue1, nil, "+1")
+	addReaction(t, user4, issue1, nil, "+1")
+	addReaction(t, user4, issue1, nil, "heart")
+	addReaction(t, ghost, issue1, nil, "-1")
+
+	err := issue1.loadReactions(x)
+	assert.NoError(t, err)
+
+	assert.Len(t, issue1.Reactions, 7)
+
+	reactions := issue1.Reactions.GroupByType()
+	assert.Len(t, reactions["heart"], 4)
+	assert.Equal(t, 2, reactions["heart"].GetMoreUserCount())
+	assert.Equal(t, "User One, User Two", reactions["heart"].GetFirstUsers())
+	assert.True(t, reactions["heart"].HasUser(1))
+	assert.False(t, reactions["heart"].HasUser(5))
+	assert.False(t, reactions["heart"].HasUser(0))
+	assert.Len(t, reactions["+1"], 2)
+	assert.Equal(t, 0, reactions["+1"].GetMoreUserCount())
+	assert.Len(t, reactions["-1"], 1)
+}
+
+func TestIssueCommentAddReaction(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	user1 := AssertExistsAndLoadBean(t, &User{ID: 1}).(*User)
+
+	issue1 := AssertExistsAndLoadBean(t, &Issue{ID: 1}).(*Issue)
+
+	comment1 := AssertExistsAndLoadBean(t, &Comment{ID: 1}).(*Comment)
+
+	addReaction(t, user1, issue1, comment1, "heart")
+
+	AssertExistsAndLoadBean(t, &Reaction{Type: "heart", UserID: user1.ID, IssueID: issue1.ID, CommentID: comment1.ID})
+}
+
+func TestIssueCommentDeleteReaction(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	user1 := AssertExistsAndLoadBean(t, &User{ID: 1}).(*User)
+	user2 := AssertExistsAndLoadBean(t, &User{ID: 2}).(*User)
+	user3 := AssertExistsAndLoadBean(t, &User{ID: 3}).(*User)
+	user4 := AssertExistsAndLoadBean(t, &User{ID: 4}).(*User)
+	ghost := NewGhostUser()
+
+	issue1 := AssertExistsAndLoadBean(t, &Issue{ID: 1}).(*Issue)
+
+	comment1 := AssertExistsAndLoadBean(t, &Comment{ID: 1}).(*Comment)
+
+	addReaction(t, user1, issue1, comment1, "heart")
+	addReaction(t, user2, issue1, comment1, "heart")
+	addReaction(t, user3, issue1, comment1, "heart")
+	addReaction(t, user4, issue1, comment1, "+1")
+	addReaction(t, ghost, issue1, comment1, "heart")
+
+	err := comment1.LoadReactions()
+	assert.NoError(t, err)
+	assert.Len(t, comment1.Reactions, 5)
+
+	reactions := comment1.Reactions.GroupByType()
+	assert.Len(t, reactions["heart"], 4)
+	assert.Len(t, reactions["+1"], 1)
+}
+
+func TestIssueCommentReactionCount(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	user1 := AssertExistsAndLoadBean(t, &User{ID: 1}).(*User)
+
+	issue1 := AssertExistsAndLoadBean(t, &Issue{ID: 1}).(*Issue)
+
+	comment1 := AssertExistsAndLoadBean(t, &Comment{ID: 1}).(*Comment)
+
+	addReaction(t, user1, issue1, comment1, "heart")
+	DeleteCommentReaction(user1, issue1, comment1, "heart")
+
+	AssertNotExistsBean(t, &Reaction{Type: "heart", UserID: user1.ID, IssueID: issue1.ID, CommentID: comment1.ID})
+}