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// Copyright (C) MongoDB, Inc. 2021-present.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
package integration
import (
"context"
"testing"
"go.mongodb.org/mongo-driver/bson"
"go.mongodb.org/mongo-driver/bson/bsoncodec"
"go.mongodb.org/mongo-driver/internal/assert"
"go.mongodb.org/mongo-driver/mongo"
"go.mongodb.org/mongo-driver/mongo/integration/mtest"
"go.mongodb.org/mongo-driver/mongo/options"
)
// finder is an object that implements FindOne and Find.
type finder interface {
FindOne(ctx context.Context, filter interface{}, opts ...*options.FindOneOptions) *mongo.SingleResult
Find(context.Context, interface{}, ...*options.FindOptions) (*mongo.Cursor, error)
}
// mockFinder implements finder.
type mockFinder struct {
docs []interface{}
err error
registry *bsoncodec.Registry
}
// FindOne mocks a findOne operation using NewSingleResultFromDocument.
func (mf *mockFinder) FindOne(_ context.Context, _ interface{}, _ ...*options.FindOneOptions) *mongo.SingleResult {
return mongo.NewSingleResultFromDocument(mf.docs[0], mf.err, mf.registry)
}
// Find mocks a find operation using NewCursorFromDocuments.
func (mf *mockFinder) Find(context.Context, interface{}, ...*options.FindOptions) (*mongo.Cursor, error) {
return mongo.NewCursorFromDocuments(mf.docs, mf.err, mf.registry)
}
// ShopItem is an item with an associated ID and price.
type ShopItem struct {
ID int `bson:"id"`
Price float64 `bson:"price"`
}
// getItem is an example function using the interface finder to test the mocking of SingleResult.
func getItem(f finder, id int) (*ShopItem, error) {
res := f.FindOne(context.Background(), bson.D{{"id", id}})
var item ShopItem
err := res.Decode(&item)
return &item, err
}
// getItems is an example function using the interface finder to test the mocking of Cursor.
func getItems(f finder) ([]ShopItem, error) {
cur, err := f.Find(context.Background(), bson.D{})
if err != nil {
return nil, err
}
var items []ShopItem
err = cur.All(context.Background(), &items)
return items, err
}
func TestMockFind(t *testing.T) {
mt := mtest.New(t, mtest.NewOptions().CreateClient(false))
insertItems := []interface{}{
ShopItem{ID: 0, Price: 1.5},
ShopItem{ID: 1, Price: 5.7},
ShopItem{ID: 2, Price: 0.25},
}
insertItem := []interface{}{ShopItem{ID: 1, Price: 5.7}}
mt.Run("mongo.Collection can be passed as interface", func(mt *mtest.T) {
// Actually insert documents to collection.
_, err := mt.Coll.InsertMany(context.Background(), insertItems)
assert.Nil(mt, err, "InsertMany error: %v", err)
// Assert that FindOne behaves as expected.
shopItem, err := getItem(mt.Coll, 1)
assert.Nil(mt, err, "getItem error: %v", err)
assert.Equal(mt, 1, shopItem.ID)
assert.Equal(mt, 5.7, shopItem.Price)
// Assert that Find behaves as expected.
shopItems, err := getItems(mt.Coll)
assert.Nil(mt, err, "getItems error: %v", err)
for i, shopItem := range shopItems {
expectedItem := insertItems[i].(ShopItem)
assert.Equal(mt, expectedItem.ID, shopItem.ID)
assert.Equal(mt, expectedItem.Price, shopItem.Price)
}
})
mt.Run("FindOne can be mocked", func(mt *mtest.T) {
// Mock a FindOne result with mockFinder.
mf := &mockFinder{docs: insertItem, err: nil, registry: nil}
// Assert that FindOne behaves as expected.
shopItem, err := getItem(mf, 1)
assert.Nil(mt, err, "getItem error: %v", err)
assert.Equal(mt, 1, shopItem.ID)
assert.Equal(mt, 5.7, shopItem.Price)
})
mt.Run("Find can be mocked", func(mt *mtest.T) {
// Mock a Find result with mockFinder.
mf := &mockFinder{docs: insertItems, err: nil, registry: nil}
// Assert that Find behaves as expected.
shopItems, err := getItems(mf)
assert.Nil(mt, err, "getItems error: %v", err)
for i, shopItem := range shopItems {
expectedItem := insertItems[i].(ShopItem)
assert.Equal(mt, expectedItem.ID, shopItem.ID)
assert.Equal(mt, expectedItem.Price, shopItem.Price)
}
})
}
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