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>

Answer 2

If you want to change the environment vaiable when you are debugging a project without break it, you can try to set it in the system environment variable.

1), create a system environment variable called number

2) use this in your code:

string str=  Environment.GetEnvironmentVariable("number",EnvironmentVariableTarget.Machine);

It will get the system environemnt variable number in your code.

3) start debugging this project and set a breakpoint on it, when you want to change the variable, you can change the value on the system environemnt variable number directly under Computer's properties.

After that,just move the cursor back to the code line, you can use the changed value.

=========================================

Update 1

When you change the value of system variable number, you should click OK to save the new value. And then move the cursor of the breakpoint back to get the new value.

Also, you should enable Edit and Continue option.