关于NUnit TestCase中ApprovalTests.Net指定单独审批文件的问询

Absolutely! This is a super common need, and ApprovalTests.Net has straightforward ways to make each TestCase use its own approval file. Let’s break down the solutions based on your scenario:

1. Automatic Naming for Simple TestCase Parameters #

If your TestCases use primitive types (strings, numbers, etc.), ApprovalTests.Net will automatically append the parameter values to the approval file name by default. For example:

using ApprovalTests.NUnit;
using NUnit.Framework;

[TestFixture]
public class CustomerReportTests
{
    [Test]
    [TestCase("CustomerA")]
    [TestCase("CustomerB")]
    public void GenerateCustomerReport_ValidId_ReturnsCorrectReport(string customerId)
    {
        var reportContent = CreateCustomerReport(customerId);
        Approvals.Verify(reportContent);
    }

    private string CreateCustomerReport(string customerId)
    {
        // Your report generation logic here
        return $"Report for {customerId}: ...";
    }
}

This will generate two distinct approval files:

• GenerateCustomerReport_ValidId_ReturnsCorrectReport.CustomerA.approved.txt
• GenerateCustomerReport_ValidId_ReturnsCorrectReport.CustomerB.approved.txt

Just make sure you’ve installed the ApprovalTests.NUnit NuGet package—this integration handles TestCase parameter detection out of the box.

2. Handling Complex TestCase Parameters #

If you’re using custom objects as TestCase parameters, you have two reliable options to get unique file names:

Option A: Override ToString() on Your Custom Type #

ApprovalTests uses the ToString() output of parameters to name files. Override it to return a unique, readable string for each instance:

public class Customer
{
    public string Id { get; set; }
    public string FullName { get; set; }

    public override string ToString()
    {
        // Return a unique identifier for the customer (avoid spaces/special chars)
        return $"{Id}_{FullName.Replace(" ", "_")}";
    }
}

[Test]
[TestCaseSource(nameof(TestCustomers))]
public void GenerateCustomerReport_ValidCustomer_ReturnsCorrectReport(Customer customer)
{
    var reportContent = CreateCustomerReport(customer);
    Approvals.Verify(reportContent);
}

private static IEnumerable<Customer> TestCustomers()
{
    yield return new Customer { Id = "C001", FullName = "Alice Smith" };
    yield return new Customer { Id = "C002", FullName = "Bob Johnson" };
}

This will create files like GenerateCustomerReport_ValidCustomer_ReturnsCorrectReport.C001_Alice_Smith.approved.txt.

Option B: Explicitly Define a Scenario Name #

Use ApprovalResults.ForScenario() to manually specify unique identifiers for each test case, giving you full control over the file name suffix without modifying the original class:

[Test]
[TestCaseSource(nameof(TestCustomers))]
public void GenerateCustomerReport_ValidCustomer_ReturnsCorrectReport(Customer customer)
{
    var reportContent = CreateCustomerReport(customer);
    // Explicitly set the scenario using customer properties
    ApprovalResults.ForScenario(customer.Id, customer.FullName);
    Approvals.Verify(reportContent);
}

This produces the same clear file naming as the ToString() approach, but lets you pick exactly which properties to use.

3. Advanced: Custom Approval Namer (For Edge Cases) #

If you need even more control over file naming (like using different conventions for different test classes), you can implement a custom IApprovalNamer and register it. This is rare for most use cases, but here’s a quick example:

public class CustomTestCaseNamer : UnitTestFrameworkNamer
{
    protected override string GetTestName()
    {
        var testContext = TestContext.CurrentContext;
        var baseName = base.GetTestName();
        var parameters = string.Join("_", testContext.Test.Arguments.Select(a => a.ToString()));
        return $"{baseName}.{parameters}";
    }
}

// Register the custom namer in your test setup
[SetUp]
public void Setup()
{
    ApprovalTests.Namers.ApprovalResults.UseNamer(() => new CustomTestCaseNamer());
}

Quick Troubleshooting Tip #

If automatic naming isn’t working, double-check that:

• You’re using ApprovalTests.NUnit (not just the core ApprovalTests package)
• Your TestCase parameters are being correctly passed to the test method
• You haven’t overridden the default namer elsewhere in your codebase

内容的提问来源于stack exchange，提问作者phoenix