如何使用 Python 3.7 模拟 Google API 库进行单元测试

How to Mock a Google API Library with Python 3.7 for Unit Testing

我正在尝试创建一组单元测试来测试 Bigquery 的 Google 客户端库。我正在努力制作一个 Unittest 文件,该文件将模拟客户端并让我测试我的输入。我提供了一个简单的脚本,其中包含一些设置功能 return 属于数据集的表列表。

有人能告诉我一个模拟 Google 客户端库的示例吗,因为我找到的文档@ https://github.com/googleapis/google-cloud-python/blob/master/bigquery/tests/unit/test_client.py 没有直接与代码的方法交互,所以我无法将它应用到我的代码中。

感谢实现此目的的任何想法或方法,我似乎无法在 Stack Overflow 上找到任何记录此问题的地方。

谢谢

from google.cloud import bigquery


def get_dataset():
    client = bigquery.Client.from_service_account_json('some_client_secret.json')

    dataset_id = 'some_project.some_dataset'

    dataset = client.get_dataset(dataset_id)

    full_dataset_id = "{}.{}".format(dataset.project, dataset.dataset_id)
    friendly_name = dataset.friendly_name
    print(
        "Got dataset '{}' with friendly_name '{}'.".format(
            full_dataset_id, friendly_name
        )
    )

    # View dataset properties
    print("Description: {}".format(dataset.description))
    print("Labels:")
    labels = dataset.labels
    if labels:
        for label, value in labels.items():
            print("\t{}: {}".format(label, value))
    else:
        print("\tDataset has no labels defined.")

    # View tables in dataset
    print("Tables:")
    tables = list(client.list_tables(dataset))  # API request(s)
    if tables:
        for table in tables:
            print("\t{}".format(table.table_id))
    else:
        print("\tThis dataset does not contain any tables.")

我也发现很难绕过身份验证部分并且只能模拟与方法的交互,所以我最终只是模拟了整个库。 :facepalm:

import sys

from unittest.mock import MagicMock

sys.modules["google.cloud.storage"] = MagicMock()

from your_application import make_app


def test_make_app():
    make_app()

我花了相当多的谷歌搜索和反复试验,才弄清楚如何做到这一点,我刚刚开始工作,所以我认为它值得分享。

unittest 提供 patch 允许您在使用 时模拟函数 ,即。替换被测代码中的 Google API 调用和 mock,这允许您进一步自定义访问该模拟的属性和调用函数的结果。

unittest 文档在此处解释补丁: https://docs.python.org/3/library/unittest.mock.html#where-to-patch

这确实解释了它是如何工作的,但我找到的最好的解释是: http://alexmarandon.com/articles/python_mock_gotchas/

这是要测试的 Python 脚本,mocking_google.py,包含对 Google 存储和 BigQuery APIs:

的引用
from google.cloud.bigquery import Client as bigqueryClient
from google.cloud.storage import Client as storageClient

def list_blobs():

    storage_client = storageClient(project='test')

    blobs = storage_client.list_blobs('bucket', prefix='prefix')

    return blobs

def extract_table():

    bigquery_client = bigqueryClient(project='test')

    job = bigquery_client.extract_table('project.dataset.table_id', destination_uris='uri')

    return job

这是单元测试:

import pytest
from unittest.mock import Mock, patch

from src.data.mocking_google import list_blobs, extract_table

@pytest.fixture
def extract_result():
    'Mock extract_job result with properties needed'
    er = Mock()
    er.return_value = 1
    return er

@pytest.fixture
def extract_job(extract_result):
    'Mock extract_job with properties needed'
    ej = Mock()
    ej.job_id = 1
    ej.result.return_value = 2
    return ej

@patch("src.data.mocking_google.storageClient")
def test_list_blobs(storageClient):

    storageClient().list_blobs.return_value = [1,2]

    blob_list = list_blobs()

    storageClient().list_blobs.assert_called_with('bucket', prefix='prefix')
    assert blob_list == [1,2]

@patch("src.data.mocking_google.bigqueryClient")
def test_extract_table(bigqueryClient,extract_job):

    bigqueryClient().extract_table.return_value = extract_job

    job = extract_table()

    bigqueryClient().extract_table.assert_called_with('project.dataset.table_id', destination_uris='uri')
    assert job.job_id == 1
    assert job.result() == 2

测试结果如下:

pytest -v src/tests/data/test_mocking_google.py============================================================ test session starts =============================================================
platform darwin -- Python 3.7.6, pytest-5.3.5, py-1.8.1, pluggy-0.13.1 -- /Users/gaya/.local/share/virtualenvs/autoencoder-recommendation-copy-zpYZ6J1x/bin/python3
cachedir: .pytest_cache
rootdir: /Users/gaya/Documents/GitHub/mlops-autoencoder-recommendation, inifile: tox.ini
plugins: cov-2.8.1
collected 2 items                                                                                                                            

src/tests/data/test_mocking_google.py::test_list_blobs PASSED                                                                          [ 50%]
src/tests/data/test_mocking_google.py::test_extract_table PASSED                                                                       [100%]

============================================================= 2 passed in 1.14s ==============================================================

如果不清楚这是如何工作的,很乐意进一步解释:)