CurrentTest and test output

CurrentTest gives information about the test that runs. Use it in code that does not get the test as a parameter, for example an assertion helper or a logger. This code does not need a reference to a test framework. CurrentTest is in the DependencyModules.Testing.Impl namespace of the DependencyModules.Testing package.

Members

Member	Value
Key	The object of the test framework for the test that runs. Compare it by reference. Two tests that run at the same time have different keys.
DisplayName	The display name of the test that runs.
Assembly	The assembly that contains the class of the test.
TryWriteLine(message)	Writes a line to the output of the test.
Provider	The ICurrentTestProvider that gives these values.

If no test runs, Key, DisplayName, and Assembly are null. Also, TryWriteLine writes nothing and returns false.

The test framework keeps the Key object until the test ends. Thus you can keep data for each test in a ConditionalWeakTable with Key as the key.

using System.Runtime.CompilerServices;
using DependencyModules.Testing.Impl;

namespace Shop.Tests;

public static class LastOrder
{
    private static readonly ConditionalWeakTable<object, string> Orders = new();

    public static void Record(string orderId)
    {
        if (CurrentTest.Key is { } test)
        {
            Orders.AddOrUpdate(test, orderId);
        }
    }

    public static string? Get() =>
        CurrentTest.Key is { } test && Orders.TryGetValue(test, out var orderId) ? orderId : null;
}

The test packages

Each test package sets CurrentTest.Provider before its first test runs. Thus CurrentTest operates with all the test packages.

Package	Source of the values
DependencyModules.xUnit and DependencyModules.xUnit4	TestContext.Current of xUnit
DependencyModules.NUnit	TestExecutionContext.CurrentContext of NUnit

A test package does not replace a provider that is already set.

Differences between the test frameworks

In xUnit, the test package builds the service provider before xUnit starts the test. Thus, in an ITestServiceSetupAttribute or an ITestStartupAttribute, Key and DisplayName are null. TryWriteLine returns false, but Assembly has a value.

In NUnit, the test package builds the service provider in the test. Thus all values are available in these attributes.

In NUnit, all iterations of a [Repeat] or [Retry] test have the same Key. NUnit does not make a different object for each iteration. Each iteration still gets a new service provider.

Write the log to the test output

TestOutputLoggerProvider is an ILoggerProvider that writes each log entry to the output of the test that runs. It is in the DependencyModules.Testing.Impl namespace. Register it in the service collection of the test. Then the logs of your application show in the output of the test.

using DependencyModules.Testing.Attributes.Interfaces;
using DependencyModules.Testing.Impl;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace Shop.Tests;

[AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Class | AttributeTargets.Method)]
public class TestLoggingAttribute : Attribute, ITestServiceSetupAttribute
{
    public void SetupServiceCollection(
        ITestMethodContext testMethod,
        IServiceCollection serviceCollection
    ) =>
        serviceCollection.AddSingleton<ILoggerProvider>(new TestOutputLoggerProvider());
}

Put [assembly: TestLogging] in the test project to use the logger for all tests. The logger factory writes to all ILoggerProvider services in the service provider. Thus the other providers also get each entry.

Each entry is one line, in the single-line format of the console logger:

info: Shop.OrderService[0] Order 42 accepted

If the entry has an exception, the exception is on the subsequent lines. If no test runs, the logger does not write the entry. For example, this occurs when a background task writes an entry after its test ends.

The default constructor uses CurrentTest.Provider. To use a different ICurrentTestProvider, give it to the constructor.