GeneratorTestContext¶

Test Roslyn source generators with fluent output assertions and snapshot testing.

Creating¶

await GenerateWith<MyGenerator>(source)
    .ShouldGenerate()
    .VerifySnapshot();

Methods¶

Method	Returns	Description
`WithAdditionalText(path, content)`	`GeneratorTestContext`	Add an additional text file
`ShouldGenerate()`	`GeneratorAssertions`	Assert generation produces output
`ShouldNotGenerate()`	`Task`	Assert no output generated
`GetResultAsync()`	`Task<GeneratorDriverRunResult>`	Get raw generator result

GeneratorAssertions¶

Chainable assertions for generator output:

await GenerateWith<MyGenerator>(source)
    .ShouldGenerate()
    .WithFileCount(2)
    .WithFileNamed("Customer.g.cs")
    .WithFileContaining("partial class Customer")
    .WithoutFileContaining("sealed")
    .WithNoDiagnostics()
    .CompilesSuccessfully()
    .VerifySnapshot();

Method	Returns	Description
`WithFileCount(count)`	`GeneratorAssertions`	Assert number of generated files
`WithFileNamed(name)`	`GeneratorAssertions`	Assert a file with this name exists
`WithFileContaining(content)`	`GeneratorAssertions`	Assert any file contains text
`WithoutFileContaining(content)`	`GeneratorAssertions`	Assert no file contains text
`WithNoDiagnostics()`	`GeneratorAssertions`	Assert zero diagnostics
`WithNoDiagnostics(filter)`	`GeneratorAssertions`	Assert no diagnostics matching filter
`WithNoErrors()`	`GeneratorAssertions`	Assert no error-level diagnostics
`WithNoWarnings()`	`GeneratorAssertions`	Assert no warning-level diagnostics
`CompilesSuccessfully()`	`GeneratorAssertions`	Assert generated code compiles
`VerifySnapshot(sourceFile)`	`Task`	Snapshot test with Verify

DiagnosticFilter¶

Configure which diagnostics to check with WithNoDiagnostics:

await GenerateWith<MyGenerator>(source)
    .ShouldGenerate()
    .WithNoDiagnostics(f => f
        .WithSeverity(DiagnosticSeverity.Error)
        .WithIds("CS0001", "CS0002"));

Method	Returns	Description
`WithSeverity(severity)`	`DiagnosticFilter`	Filter by severity level
`WithId(id)`	`DiagnosticFilter`	Filter by single diagnostic ID
`WithIds(ids)`	`DiagnosticFilter`	Filter by multiple IDs
`WithMessageContaining(text)`	`DiagnosticFilter`	Filter by message content

Snapshot Testing¶

VerifySnapshot() uses Verify to snapshot generated output. On first run it creates .verified.txt files; subsequent runs compare against them.

[Test]
public async Task Generates_customer_code()
{
    await GenerateWith<MyGenerator>(source)
        .ShouldGenerate()
        .VerifySnapshot();
}

Additional Text¶

For generators that use AdditionalTexts (e.g., user templates):

await GenerateWith<MyGenerator>(source)
    .WithAdditionalText(
        "Templates/MyProject/Customer.scriban-cs",
        customTemplateContent)
    .ShouldGenerate()
    .WithFileNamed("Customer.g.cs");