如何为 Durable Azure 函数编写单元测试？

Question

I'm writing an Azure Durable Function, and I would like to write some unit tests for this whole Azure Function.

I tried to trigger the Client function (the "Start" function, as it is often called), but I can't make it work.

I'm doing this for two reasons:

1. It's frustrating to run the Azure Function code by running "func host start" (or pressing F5), then going to my browser, finding the right tab, going to http://localhost:7071/api/orchestrators/FooOrchestrator and going back to VS Code to debug my code.
2. I'd like to write some unit tests to ensure the quality of my project's code. Therefore I'm open to suggestions, maybe it would be easier to only test the execution of Activity functions.

Client Function code

This is the code of my Client function, mostly boilerplate code like this one

import logging
import azure.functions as func
import azure.durable_functions as df

async def main(req: func.HttpRequest, starter: str) -> func.HttpResponse:
    # 'starter' seems to contains the JSON data about
    # the URLs to monitor, stop, etc, the Durable Function
    client = df.DurableOrchestrationClient(starter)

    # The Client function knows which orchestrator to call
    # according to 'function_name'
    function_name = req.route_params["functionName"]

    # This part fails with a ClientConnectorError
    # with the message: "Cannot connect to host 127.0.0.1:17071 ssl:default"
    instance_id = await client.start_new(function_name, None, None)

    logging.info(f"Orchestration '{function_name}' starter with ID = '{instance_id}'.")

    return client.create_check_status_response(req, instance_id)

Unit test try

Then I tried to write some code to trigger this Client function like I did for some "classic" Azure Functions:

import asyncio
import json

if __name__ == "__main__":
    # Build a simple request to trigger the Client function
    req = func.HttpRequest(
        method="GET",
        body=None,
        url="don't care?",
        # What orchestrator do you want to trigger?
        route_params={"functionName": "FooOrchestrator"},
    )

    # I copy pasted the data that I obtained when I ran the Durable Function
    # with "func host start"
    starter = {
        "taskHubName": "TestHubName",
        "creationUrls": {
            "createNewInstancePostUri": "http://localhost:7071/runtime/webhooks/durabletask/orchestrators/{functionName}[/{instanceId}]?code=aakw1DfReOkYCTFMdKPaA1Q6bSfnHZ/0lzvKsS6MVXCJdp4zhHKDJA==",
            "createAndWaitOnNewInstancePostUri": "http://localhost:7071/runtime/webhooks/durabletask/orchestrators/{functionName}[/{instanceId}]?timeout={timeoutInSeconds}&pollingInterval={intervalInSeconds}&code=aakw1DfReOkYCTFMdKPaA1Q6bSfnHZ/0lzvKsS6MVXCJdp4zhHKDJA==",
        },
        "managementUrls": {
            "id": "INSTANCEID",
            "statusQueryGetUri": "http://localhost:7071/runtime/webhooks/durabletask/instances/INSTANCEID?taskHub=TestHubName&connection=Storage&code=aakw1DfReOkYCTFMdKPaA1Q6bSfnHZ/0lzvKsS6MVXCJdp4zhHKDJA==",
            "sendEventPostUri": "http://localhost:7071/runtime/webhooks/durabletask/instances/INSTANCEID/raiseEvent/{eventName}?taskHub=TestHubName&connection=Storage&code=aakw1DfReOkYCTFMdKPaA1Q6bSfnHZ/0lzvKsS6MVXCJdp4zhHKDJA==",
            "terminatePostUri": "http://localhost:7071/runtime/webhooks/durabletask/instances/INSTANCEID/terminate?reason={text}&taskHub=TestHubName&connection=Storage&code=aakw1DfReOkYCTFMdKPaA1Q6bSfnHZ/0lzvKsS6MVXCJdp4zhHKDJA==",
            "rewindPostUri": "http://localhost:7071/runtime/webhooks/durabletask/instances/INSTANCEID/rewind?reason={text}&taskHub=TestHubName&connection=Storage&code=aakw1DfReOkYCTFMdKPaA1Q6bSfnHZ/0lzvKsS6MVXCJdp4zhHKDJA==",
            "purgeHistoryDeleteUri": "http://localhost:7071/runtime/webhooks/durabletask/instances/INSTANCEID?taskHub=TestHubName&connection=Storage&code=aakw1DfReOkYCTFMdKPaA1Q6bSfnHZ/0lzvKsS6MVXCJdp4zhHKDJA==",
            "restartPostUri": "http://localhost:7071/runtime/webhooks/durabletask/instances/INSTANCEID/restart?taskHub=TestHubName&connection=Storage&code=aakw1DfReOkYCTFMdKPaA1Q6bSfnHZ/0lzvKsS6MVXCJdp4zhHKDJA==",
        },
        "baseUrl": "http://localhost:7071/runtime/webhooks/durabletask",
        "requiredQueryStringParameters": "code=aakw1DfReOkYCTFMdKPaA1Q6bSfnHZ/0lzvKsS6MVXCJdp4zhHKDJA==",
        "rpcBaseUrl": "http://127.0.0.1:17071/durabletask/",
    }

    # I need to use async methods because the "main" of the Client
    # uses async.
    reponse = asyncio.get_event_loop().run_until_complete(
        main(req, starter=json.dumps(starter))
    )

But unfortunately the Client function still fails in the await client.start_new(function_name, None, None) part.

How could I write some unit tests for my Durable Azure Function in Python?

Technical information

• Python version: 3.9
• Azure Functions Core Tools version 4.0.3971
• Function Runtime Version: 4.0.1.16815

Answer 1

Not sure if this will help which is the official documentation from Microsoft on the Unit testing for what you are looking for - https://github.com/kemurayama/durable-functions-for-python-unittest-sample