add support for new list all orgs method

Fixes #215.

Change-Id: Ic17192cc0b1dbe02745e4c7f76bd81457f73141a

github/orgs.go

@@ -68,6 +68,39 @@ func (p Plan) String() string {
 	return Stringify(p)
 }
 
+// OrganizationsListOptions specifies the optional parameters to the
+// OrganizationsService.ListAll method.
+type OrganizationsListOptions struct {
+	// Since filters Organizations by ID.
+	Since int `url:"since,omitempty"`
+}
+
+// ListAll lists all organizations, in the order that they were created on GitHub.
+//
+// Note: Pagination is powered exclusively by the since parameter. To continue
+// listing the next set of organizations, use the ID of the last-returned organization
+// as the opts.Since parameter for the next call.
+//
+// GitHub API docs: https://developer.github.com/v3/orgs/#list-all-organizations
+func (s *OrganizationsService) ListAll(opt *OrganizationsListOptions) ([]Organization, *Response, error) {
+	u, err := addOptions("organizations", opt)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	req, err := s.client.NewRequest("GET", u, nil)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	orgs := []Organization{}
+	resp, err := s.client.Do(req, &orgs)
+	if err != nil {
+		return nil, resp, err
+	}
+	return orgs, resp, err
+}
+
 // List the organizations for a user.  Passing the empty string will list
 // organizations for the authenticated user.
 //

github/orgs_test.go

@@ -13,6 +13,29 @@ import (
 	"testing"
 )
 
+func TestOrganizationsService_ListAll(t *testing.T) {
+	setup()
+	defer teardown()
+
+	since := 1342004
+	mux.HandleFunc("/organizations", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		testFormValues(t, r, values{"since": "1342004"})
+		fmt.Fprint(w, `[{"id":4314092}]`)
+	})
+
+	opt := &OrganizationsListOptions{Since: since}
+	orgs, _, err := client.Organizations.ListAll(opt)
+	if err != nil {
+		t.Errorf("Organizations.ListAll returned error: %v", err)
+	}
+
+	want := []Organization{{ID: Int(4314092)}}
+	if !reflect.DeepEqual(orgs, want) {
+		t.Errorf("Organizations.ListAll returned %+v, want %+v", orgs, want)
+	}
+}
+
 func TestOrganizationsService_List_authenticatedUser(t *testing.T) {
 	setup()
 	defer teardown()