Add (us)subscribe to/from issues (#479)

And extend the MergeEvent struct.

event_types.go

@@ -490,6 +490,24 @@ type MergeEvent struct {
 		Username  string `json:"username"`
 		AvatarURL string `json:"avatar_url"`
 	} `json:"assignee"`
+	Changes struct {
+		AssigneeID struct {
+			Previous int `json:"previous"`
+			Current  int `json:"current"`
+		} `json:"assignee_id"`
+		Description struct {
+			Previous string `json:"previous"`
+			Current  string `json:"current"`
+		} `json:"description"`
+		Labels struct {
+			Previous []Label `json:"previous"`
+			Current  []Label `json:"current"`
+		} `json:"labels"`
+		UpdatedByID struct {
+			Previous int `json:"previous"`
+			Current  int `json:"current"`
+		} `json:"updated_by_id"`
+	} `json:"changes"`
 }
 
 // WikiPageEvent represents a wiki page event.

issues.go

@@ -363,6 +363,60 @@ func (s *IssuesService) DeleteIssue(pid interface{}, issue int, options ...Optio
 	return s.client.Do(req, nil)
 }
 
+// SubscribeToIssue subscribes the authenticated user to the given issue to
+// receive notifications. If the user is already subscribed to the issue, the
+// status code 304 is returned.
+//
+// GitLab API docs:
+// https://docs.gitlab.com/ce/api/merge_requests.html#subscribe-to-a-merge-request
+func (s *IssuesService) SubscribeToIssue(pid interface{}, issue int, options ...OptionFunc) (*Issue, *Response, error) {
+	project, err := parseID(pid)
+	if err != nil {
+		return nil, nil, err
+	}
+	u := fmt.Sprintf("projects/%s/issues/%d/subscribe", url.QueryEscape(project), issue)
+
+	req, err := s.client.NewRequest("POST", u, nil, options)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	i := new(Issue)
+	resp, err := s.client.Do(req, i)
+	if err != nil {
+		return nil, resp, err
+	}
+
+	return i, resp, err
+}
+
+// UnsubscribeFromIssue unsubscribes the authenticated user from the given
+// issue to not receive notifications from that merge request. If the user
+// is not subscribed to the issue, status code 304 is returned.
+//
+// GitLab API docs:
+// https://docs.gitlab.com/ce/api/merge_requests.html#unsubscribe-from-a-merge-request
+func (s *IssuesService) UnsubscribeFromIssue(pid interface{}, issue int, options ...OptionFunc) (*Issue, *Response, error) {
+	project, err := parseID(pid)
+	if err != nil {
+		return nil, nil, err
+	}
+	u := fmt.Sprintf("projects/%s/issues/%d/unsubscribe", url.QueryEscape(project), issue)
+
+	req, err := s.client.NewRequest("POST", u, nil, options)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	i := new(Issue)
+	resp, err := s.client.Do(req, i)
+	if err != nil {
+		return nil, resp, err
+	}
+
+	return i, resp, err
+}
+
 // ListMergeRequestsClosingIssueOptions represents the available
 // ListMergeRequestsClosingIssue() options.
 //

merge_requests.go

@@ -684,8 +684,8 @@ func (s *MergeRequestsService) GetSingleMergeRequestDiffVersion(pid interface{},
 	return v, resp, err
 }
 
-// SubscribeToMergeRequest subscribes the authenticated user to the given merge request
-// to receive notifications. If the user is already subscribed to the
+// SubscribeToMergeRequest subscribes the authenticated user to the given merge
+// request to receive notifications. If the user is already subscribed to the
 // merge request, the status code 304 is returned.
 //
 // GitLab API docs:
@@ -711,9 +711,10 @@ func (s *MergeRequestsService) SubscribeToMergeRequest(pid interface{}, mergeReq
 	return m, resp, err
 }
 
-// UnsubscribeFromMergeRequest unsubscribes the authenticated user from the given merge request
-// to not receive notifications from that merge request. If the user is
-// not subscribed to the merge request, status code 304 is returned.
+// UnsubscribeFromMergeRequest unsubscribes the authenticated user from the
+// given merge request to not receive notifications from that merge request.
+// If the user is not subscribed to the merge request, status code 304 is
+// returned.
 //
 // GitLab API docs:
 // https://docs.gitlab.com/ce/api/merge_requests.html#unsubscribe-from-a-merge-request