local.settings.json in Integration/Unit Tests

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Core Tools Version: 96 Commit hash: c54cdc36323e9543ba11fb61dd107616e9022bba Function Runtime Version: 3.0.14916.0

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C#

Question

I’m trying to use xUnit to test an Azure Function. After setting up my test environment using the following logic, the test runs; however, the Values in local.settings.json are not loaded into environment variables, as they would be if I ran the function using func start.

What is the recommended way to load those values to environment variables when writing tests like the following?

var startup = new Startup();
var host = new HostBuilder()
	.ConfigureWebJobs(startup.Configure)
	.Build();

var sut = new Function1(....);

Assert.Equal(....);

Thank you, Ben

[bgribaudo]

Hi @v-anvari,

Thanks! The challenge is that when running automated (unit/integration) tests, the function app settings are not automatically getting loaded into environment variables, so I can’t read them out using System.Environment.GetEnvironmentVariable (e.g. the example you linked to).

I ended up creating a helper method that the appropriate test class(es) call which emulates what func start does (reading each key-value pair local.settings.json’s Values element into an environment variable):

static void ConfigureEnvironmentVariablesFromLocalSettings()
{
	var path = Path.GetDirectoryName(typeof(MyClass).Assembly.Location);
	var json = File.ReadAllText(Path.Join(path, "local.settings.json"));
	var parsed = Newtonsoft.Json.Linq.JObject.Parse(json).Value<Newtonsoft.Json.Linq.JObject>("Values");

	foreach (var item in parsed)
	{
		Environment.SetEnvironmentVariable(item.Key, item.Value.ToString());
	}
}

Usage Example:

ConfigureEnvironmentVariablesFromLocalSettings();

var startup = new Startup();
var host = new HostBuilder()
  .ConfigureWebJobs(startup.Configure)
  .Build();

Is something like this the recommended way to make function app settings available during integration testing or is there a better alternative?

Note: The above has some catches, such as potential variable value conflicts due to parallel test execution. Also, depending on the use case, it may be desirable to ensure that environment variables are reset to their original values at test class teardown (code to do this not shown above).

Thanks, Ben

[bgribaudo]

Thank you, @asears, for those links.