README.md

AzureFunctions.TestFramework.DataExplorer

Azure Data Explorer (Kusto) Input and Output binding support for the Azure Functions Test Framework.

Installation

dotnet add package AzureFunctions.TestFramework.DataExplorer

Supported bindings

Binding	Attribute	Description
[KustoInput]	Input	Reads rows from an Azure Data Explorer query result
[KustoOutput]	Output	Ingests rows into an Azure Data Explorer table — captured via FunctionInvocationResult

ℹ️ Azure Data Explorer has no trigger binding in the isolated worker extension. Use another trigger type (for example Queue, Timer, or HTTP) and assert Kusto input/output behavior in that invocation.

Kusto Input Binding

Register fake rows via the builder so they are injected automatically for every invocation:

var host = await new FunctionsTestHostBuilder()
    .WithFunctionsAssembly(typeof(MyFunction).Assembly)
    .WithHostBuilderFactory(Program.CreateHostBuilder)
    // Inject rows for [KustoInput("MyDb", KqlCommand = "InputTable | take 10")]
    .WithKustoInputRows(
        database: "MyDb",
        table: "InputTable",
        rows:
        [
            new Product { Id = 1, Name = "Widget" },
            new Product { Id = 2, Name = "Gadget" }
        ])
    .BuildAndStartAsync();

Use WithKustoInputRows<T>(database, table, T row) to inject a single row, WithKustoInputRows<T>(database, table, IReadOnlyList<T> rows) to inject multiple rows, and WithKustoInputJson(database, table, json) to inject raw JSON.

Function example

[Function("ReadKustoProducts")]
public void Run(
    [QueueTrigger("kusto-input-queue")] string queueMessage,
    [KustoInput("MyDb", KqlCommand = "InputTable | take 10")] IReadOnlyList<Product> products)
{
    foreach (var product in products)
        _logger.LogInformation("Product: {Name}", product.Name);
}

Kusto Output Binding

Output bindings are captured automatically via FunctionInvocationResult:

var result = await host.InvokeQueueAsync("WriteKustoOutput", "source");

Assert.True(result.Success);
var written = result.ReadReturnValueAs<Product>();
Assert.Equal("copy:source", written?.Name);

Function example

[Function("WriteKustoOutput")]
[KustoOutput("MyDb", TableName = "OutputTable")]
public Product Run([QueueTrigger("kusto-output-queue")] string message)
{
    return new Product { Id = 1, Name = $"copy:{message}" };
}

Known limitation

WithKustoInputRows(database, table, ...) matches by database and the first table identifier in KqlCommand (for example "InputTable | take 10"). If your query starts with declare statements or does not begin with a table identifier, use WithKustoInputJson(...) with a matching database/table registration strategy in your tests.

Testing across all four flavours

Add the Data Explorer package reference to your test project and all four function-app test flavours:

<PackageReference Include="AzureFunctions.TestFramework.DataExplorer" />

See the 4-flavour matrix test pattern for the concrete test class structure.