ListTodo allows for ListOptions

The GitLab API Docs are missing these options, but they are supported as
the GitLab specs show[1], and can be verified for a signed in user[2].

Including them here breaks the interface when users used assignments
without Field names.

To test the change, an PerPage list option was set in the test. This
doesn't influence the test, but does test the interface.

[1]: https://gitlab.com/gitlab-org/gitlab-ce/blob/4325986f25b7523acac49cfaefb7149208ae8553/spec/requests/api/todos_spec.rb#L39
[2]: https://gitlab.com/api/v4/todos?per_page=1

testdata/list_todos.json

+[
+  {
+    "id": 1,
+    "state": "pending",
+    "target": {
+      "id": 1,
+      "approvals_before_merge": 2
+    }
+  },
+  {
+    "id": 2,
+    "state": "pending",
+    "target": {
+      "id": 2,
+      "approvals_before_merge": null
+    }
+  }
+]

todos.go

@@ -121,6 +121,7 @@ func (t Todo) String() string {
 //
 // GitLab API docs: https://docs.gitlab.com/ce/api/todos.html#get-a-list-of-todos
 type ListTodosOptions struct {
+	ListOptions
 	Action    *TodoAction `url:"action,omitempty" json:"action,omitempty"`
 	AuthorID  *int        `url:"author_id,omitempty" json:"author_id,omitempty"`
 	ProjectID *int        `url:"project_id,omitempty" json:"project_id,omitempty"`

todos_test.go

 package gitlab
 
 import (
-	"fmt"
 	"net/http"
-	"reflect"
 	"testing"
+
+	"github.com/stretchr/testify/require"
 )
 
 func TestListTodos(t *testing.T) {
@@ -13,21 +13,16 @@ func TestListTodos(t *testing.T) {
 
 	mux.HandleFunc("/api/v4/todos", func(w http.ResponseWriter, r *http.Request) {
 		testMethod(t, r, "GET")
-		fmt.Fprint(w, `[{"id":1,"state": "pending","target":{"id":1,"approvals_before_merge":2}},{"id":2,"state":"pending","target":{"id":2,"approvals_before_merge":null}}]`)
+		mustWriteHTTPResponse(t, w, "testdata/list_todos.json")
 	})
 
-	opts := &ListTodosOptions{}
+	opts := &ListTodosOptions{ListOptions: ListOptions{PerPage: 2}}
 	todos, _, err := client.Todos.ListTodos(opts)
 
-	if err != nil {
-		t.Errorf("Todos.ListTodos returned error: %v", err)
-	}
+	require.NoError(t, err)
 
 	want := []*Todo{{ID: 1, State: "pending", Target: TodoTarget{ID: 1, ApprovalsBeforeMerge: 2}}, {ID: 2, State: "pending", Target: TodoTarget{ID: 2}}}
-	if !reflect.DeepEqual(want, todos) {
-		t.Errorf("Todos.ListTodos returned %+v, want %+v", todos, want)
-	}
-
+	require.Equal(t, want, todos)
 }
 
 func TestMarkAllTodosAsDone(t *testing.T) {
@@ -40,10 +35,7 @@ func TestMarkAllTodosAsDone(t *testing.T) {
 	})
 
 	_, err := client.Todos.MarkAllTodosAsDone()
-
-	if err != nil {
-		t.Fatalf("Todos.MarkTodosRead returns an error: %v", err)
-	}
+	require.NoError(t, err)
 }
 
 func TestMarkTodoAsDone(t *testing.T) {
@@ -55,8 +47,5 @@ func TestMarkTodoAsDone(t *testing.T) {
 	})
 
 	_, err := client.Todos.MarkTodoAsDone(1)
-
-	if err != nil {
-		t.Fatalf("Todos.MarkTodoRead returns an error: %v", err)
-	}
+	require.NoError(t, err)
 }