How to use environment variables in unit tests (.net core)

Question

I have got a method that I am trying to test which uses environment variables from my "local.settings.json"

private static string _environmentVar = Environment.GetEnvironmentVariable("envirnomentVarConfig");

public string MyMethod()
{
    var result = DoStuff(_environmentVar)
    return result;  
}

In my test I am calling this method and when debugging, I can see that _environmentVar is null.

Do I need to setup envirnomentVarConfig in the test? If so how?

Answer 1

Solved this by setting up the variable in the test using:

Environment.SetEnvironmentVariable("environmentVarConfig", "environmentVarValue");

Answer 2

You can specify environment variables in the .runsettings file:

<?xml version="1.0" encoding="utf-8"?>
<RunSettings>
    <RunConfiguration>
        <EnvironmentVariables>
            <YOUR_VARIABLE>Value for your variable</YOUR_VARIABLE>
            <SOME_OTHER_VARIABLE>With another Value</SOME_OTHER_VARIABLE>
        </EnvironmentVariables>
    </RunConfiguration>
</RunSettings>

Alternatively you can implement a DataCollector which provides environment variables via ITestExecutionEnvironmentSpecifier

// Add a reference to nuget package `Microsoft.TestPlatform.ObjectModel`
// The assembly name must end with `Collector` (i.e. match `*collector.dll`)

[DataCollectorFriendlyName("my own example collector")]
[DataCollectorTypeUri("datacollector://myown/examplecollector/1.0")]
public class MyDataCollector : DataCollector, ITestExecutionEnvironmentSpecifier
{
    public override void Initialize(
        XmlElement configurationElement,
        DataCollectionEvents events,
        DataCollectionSink dataSink,
        DataCollectionLogger logger,
        DataCollectionEnvironmentContext environmentContext)
    {
        // inspect configurationElement for your custom settings
    }

    public IEnumerable<KeyValuePair<string, string>> GetTestExecutionEnvironmentVariables()
    {
        return new Dictionary<string, string>
        {
            ["YOUR_VARIABLE"] = "your value",
        };
    }
}

You also configure your data collector via the .runsettings file:

<?xml version="1.0" encoding="utf-8"?>
<RunSettings>
    <RunConfiguration>
        <TestAdaptersPaths>path/where/to/find/your/collector</TestAdaptersPaths>
    </RunConfiguration>
    <DataCollectionRunSettings>
        <DataCollectors>
            <DataCollector friendlyName="my own example collector" uri="datacollector://myown/examplecollector/1.0">
                <Configuration>
                    <SomeSettingHere/>
                </Configuration>
            </DataCollector>
        </DataCollectors>
    </DataCollectionRunSettings>
</RunSettings>

Answer 3

I was able to do it globally for tests on WebHostBuilder according to documentation https://learn.microsoft.com/en-us/aspnet/core/test/integration-tests?view=aspnetcore-6.0#set-the-environment

protected override IWebHostBuilder CreateWebHostBuilder() =>
       base.CreateWebHostBuilder().UseEnvironment("Testing");