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Merged
thomhurst merged 1 commit into from
Dec 19, 2025
+109 −63
Merged

Better exception messages when injected data sources throw #4108

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172 changes: 109 additions & 63 deletions TUnit.Engine/Building/TestBuilder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -459,45 +459,56 @@ await _objectLifecycleService.RegisterObjectAsync(
const string skipReason = "Data source returned no data";

Type[] resolvedClassGenericArgs;
Exception? genericResolutionException = null;
try
{
resolvedClassGenericArgs = metadata.TestClassType.IsGenericTypeDefinition
? TryInferClassGenericsFromDataSources(metadata)
: Type.EmptyTypes;
}
catch
catch (Exception ex)
{
resolvedClassGenericArgs = Type.EmptyTypes;
genericResolutionException = ex;
}

var testData = new TestData
// If generic type inference failed, create a failed test instead of skipped
if (genericResolutionException != null)
{
TestClassInstanceFactory = () => Task.FromResult<object>(SkippedTestInstance.Instance),
ClassDataSourceAttributeIndex = classDataAttributeIndex,
ClassDataLoopIndex = classDataLoopIndex,
ClassData = classData,
MethodDataSourceAttributeIndex = methodDataAttributeIndex,
MethodDataLoopIndex = 1, // Use 1 since we're creating a single skipped test
MethodData = [],
RepeatIndex = 0,
InheritanceDepth = metadata.InheritanceDepth,
ResolvedClassGenericArguments = resolvedClassGenericArgs,
ResolvedMethodGenericArguments = Type.EmptyTypes
};

var testSpecificContext = new TestBuilderContext
var failedTest = await CreateFailedTestForDataGenerationError(metadata, genericResolutionException);
tests.Add(failedTest);
}
else
{
TestMetadata = metadata.MethodMetadata,
Events = new TestContextEvents(),
StateBag = new ConcurrentDictionary<string, object?>(),
ClassConstructor = testBuilderContext.ClassConstructor,
DataSourceAttribute = methodDataSource,
InitializedAttributes = attributes
};

var test = await BuildTestAsync(metadata, testData, testSpecificContext);
test.Context.SkipReason = skipReason;
tests.Add(test);
var testData = new TestData
{
TestClassInstanceFactory = () => Task.FromResult<object>(SkippedTestInstance.Instance),
ClassDataSourceAttributeIndex = classDataAttributeIndex,
ClassDataLoopIndex = classDataLoopIndex,
ClassData = classData,
MethodDataSourceAttributeIndex = methodDataAttributeIndex,
MethodDataLoopIndex = 1, // Use 1 since we're creating a single skipped test
MethodData = [],
RepeatIndex = 0,
InheritanceDepth = metadata.InheritanceDepth,
ResolvedClassGenericArguments = resolvedClassGenericArgs,
ResolvedMethodGenericArguments = Type.EmptyTypes
};

var testSpecificContext = new TestBuilderContext
{
TestMetadata = metadata.MethodMetadata,
Events = new TestContextEvents(),
StateBag = new ConcurrentDictionary<string, object?>(),
ClassConstructor = testBuilderContext.ClassConstructor,
DataSourceAttribute = methodDataSource,
InitializedAttributes = attributes
};

var test = await BuildTestAsync(metadata, testData, testSpecificContext);
test.Context.SkipReason = skipReason;
tests.Add(test);
}
}
}
}
Expand All @@ -508,45 +519,56 @@ await _objectLifecycleService.RegisterObjectAsync(
const string skipReason = "Data source returned no data";

Type[] resolvedClassGenericArgs;
Exception? genericResolutionException = null;
try
{
resolvedClassGenericArgs = metadata.TestClassType.IsGenericTypeDefinition
? TryInferClassGenericsFromDataSources(metadata)
: Type.EmptyTypes;
}
catch
catch (Exception ex)
{
resolvedClassGenericArgs = Type.EmptyTypes;
genericResolutionException = ex;
}

var testData = new TestData
// If generic type inference failed, create a failed test instead of skipped
if (genericResolutionException != null)
{
TestClassInstanceFactory = () => Task.FromResult<object>(SkippedTestInstance.Instance),
ClassDataSourceAttributeIndex = classDataAttributeIndex,
ClassDataLoopIndex = 1, // Use 1 since we're creating a single skipped test
ClassData = [],
MethodDataSourceAttributeIndex = 0,
MethodDataLoopIndex = 0,
MethodData = [],
RepeatIndex = 0,
InheritanceDepth = metadata.InheritanceDepth,
ResolvedClassGenericArguments = resolvedClassGenericArgs,
ResolvedMethodGenericArguments = Type.EmptyTypes
};

var testSpecificContext = new TestBuilderContext
var failedTest = await CreateFailedTestForDataGenerationError(metadata, genericResolutionException);
tests.Add(failedTest);
}
else
{
TestMetadata = metadata.MethodMetadata,
Events = new TestContextEvents(),
StateBag = new ConcurrentDictionary<string, object?>(),
ClassConstructor = testBuilderContext.ClassConstructor,
DataSourceAttribute = classDataSource,
InitializedAttributes = attributes
};

var test = await BuildTestAsync(metadata, testData, testSpecificContext);
test.Context.SkipReason = skipReason;
tests.Add(test);
var testData = new TestData
{
TestClassInstanceFactory = () => Task.FromResult<object>(SkippedTestInstance.Instance),
ClassDataSourceAttributeIndex = classDataAttributeIndex,
ClassDataLoopIndex = 1, // Use 1 since we're creating a single skipped test
ClassData = [],
MethodDataSourceAttributeIndex = 0,
MethodDataLoopIndex = 0,
MethodData = [],
RepeatIndex = 0,
InheritanceDepth = metadata.InheritanceDepth,
ResolvedClassGenericArguments = resolvedClassGenericArgs,
ResolvedMethodGenericArguments = Type.EmptyTypes
};

var testSpecificContext = new TestBuilderContext
{
TestMetadata = metadata.MethodMetadata,
Events = new TestContextEvents(),
StateBag = new ConcurrentDictionary<string, object?>(),
ClassConstructor = testBuilderContext.ClassConstructor,
DataSourceAttribute = classDataSource,
InitializedAttributes = attributes
};

var test = await BuildTestAsync(metadata, testData, testSpecificContext);
test.Context.SkipReason = skipReason;
tests.Add(test);
}
}
}

Expand Down Expand Up @@ -1314,6 +1336,26 @@ internal class TestData
public Type[] ResolvedMethodGenericArguments { get; set; } = Type.EmptyTypes;
}

/// <summary>
/// Result of attempting to create an instance for method data sources.
/// Captures either success with an instance or failure with the exception.
/// </summary>
private readonly struct InstanceCreationResult
{
public object? Instance { get; }
public Exception? Exception { get; }
public bool Success => Exception == null;

private InstanceCreationResult(object? instance, Exception? exception)
{
Instance = instance;
Exception = exception;
}

public static InstanceCreationResult CreateSuccess(object? instance) => new(instance, null);
public static InstanceCreationResult CreateFailure(Exception exception) => new(null, exception);
}

#if NET6_0_OR_GREATER
[RequiresUnreferencedCode("Test building in reflection mode uses generic type resolution which requires unreferenced code")]
#endif
Expand Down Expand Up @@ -1403,14 +1445,18 @@ public async IAsyncEnumerable<AbstractExecutableTest> BuildTestsStreamingAsync(

if (needsInstanceForMethodDataSources)
{
instanceForMethodDataSources = await CreateInstanceForMethodDataSources(
var instanceResult = await CreateInstanceForMethodDataSources(
metadata, classDataAttributeIndex, classDataLoopIndex, classData);

if (instanceForMethodDataSources == null)
if (!instanceResult.Success)
{
continue; // Skip if instance creation failed
// Yield a failed test instead of silently skipping
yield return await CreateFailedTestForInstanceDataSourceError(metadata, instanceResult.Exception!);
continue;
}

instanceForMethodDataSources = instanceResult.Instance!;

// Initialize property data sources on the early instance so that
// method data sources can access fully-initialized properties.
var tempObjectBag = new ConcurrentDictionary<string, object?>();
Expand Down Expand Up @@ -1472,7 +1518,7 @@ await _objectLifecycleService.RegisterObjectAsync(
#if NET6_0_OR_GREATER
[RequiresUnreferencedCode("Generic type resolution for instance creation uses reflection")]
#endif
private Task<object?> CreateInstanceForMethodDataSources(
private Task<InstanceCreationResult> CreateInstanceForMethodDataSources(
TestMetadata metadata, int classDataAttributeIndex, int classDataLoopIndex, object?[] classData)
{
try
Expand All @@ -1495,22 +1541,22 @@ await _objectLifecycleService.RegisterObjectAsync(
try
{
var resolution = TestGenericTypeResolver.Resolve(metadata, tempTestData);
return Task.FromResult<object?>(metadata.InstanceFactory(resolution.ResolvedClassGenericArguments, classData));
return Task.FromResult(InstanceCreationResult.CreateSuccess(metadata.InstanceFactory(resolution.ResolvedClassGenericArguments, classData)));
}
catch (GenericTypeResolutionException) when (classData.Length == 0)
{
var resolvedTypes = TryInferClassGenericsFromDataSources(metadata);
return Task.FromResult<object?>(metadata.InstanceFactory(resolvedTypes, classData));
return Task.FromResult(InstanceCreationResult.CreateSuccess(metadata.InstanceFactory(resolvedTypes, classData)));
}
}
else
{
return Task.FromResult<object?>(metadata.InstanceFactory([], classData));
return Task.FromResult(InstanceCreationResult.CreateSuccess(metadata.InstanceFactory([], classData)));
}
}
catch
catch (Exception ex)
{
return Task.FromResult<object?>(null);
return Task.FromResult(InstanceCreationResult.CreateFailure(ex));
}
}

Expand Down
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