Passing environment variables to tests in Visual Studio 2019

Question

Seems like a pretty trivial question, but to my surprise I found no mention of this on the web.

I've got an Nunit test project (that someone else wrote and I don't want to change too much), that I need to debug. These tests depend on environment variables that they read using Environment.GetEnvironmentVariable.

My question is: is there a way I can pass environment variables when debugging tests in Visual Studio?

I know I can pass environment variables when I debug an executable project through Project Properties->Debug, but this doesn't take effect when running tests (e.g. via Test Explorer). I also know I can pass test parameters through a .runsettings files, but these are accessible only through the TestContext class.

Answer 1

I also know I can pass test parameters through a .runsettings files, but these are accessible only through the TestContext class.

You can also 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 (if you need to run code or calculate the value) 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>