skill-testing

Skill: AL Testing & Test Strategy

Purpose

Design test strategies, implement Given/When/Then test patterns, build reusable library codeunits, test Copilot features with AI Test Toolkit, and integrate testing into the conductor's TDD cycle for AL Business Central extensions.

When to Load

This skill should be loaded when:

• A test strategy or test plan needs to be designed for a feature
• Test codeunits need to be created (unit, integration, UI)
• The conductor runs a TDD cycle (RED → GREEN → REFACTOR)
• Copilot/AI-powered features need testing with AI Test Toolkit
• Test data builders or library codeunits need to be created
• Test failures need analysis or coverage gaps need to be addressed

Core Patterns

When BC29 test lifecycle instrumentation is needed, read the test section of AL18 capability checks. TestHandlers / ITestHandler require target declaration checks and do not replace the approved runner. Test-library versions need not equal the app version: check dependency identity, minimum version, runtime and APIs. Unknown compatibility limits the affected validation; it does not automatically block drafting the spec.

Pattern 1: Given/When/Then Test Structure

Every test follows GWT with explicit comments and a descriptive name:

codeunit 50100 "Discount Calculation Tests"
{
    Subtype = Test;
    TestPermissions = Disabled;   // runs as SUPER; not a rollback setting

    var
        Assert: Codeunit Assert;
        LibrarySales: Codeunit "Library - Sales";
        LibraryRandom: Codeunit "Library - Random";
        IsInitialized: Boolean;

    [Test]
    procedure CalculateLineDiscount_VolumeOver100_Applies15Percent()
    var
        SalesLine: Record "Sales Line";
        DiscountMgt: Codeunit "Contoso Discount Management";
        Result: Decimal;
    begin
        // [SCENARIO] Volume discount is correctly applied for quantities ≥ 100
        Initialize();

        // [GIVEN] A sales line with quantity 100 and unit price 10
        CreateSalesLineWithQty(SalesLine, 100, 10);

        // [GIVEN] Volume discount setup: 100+ units → 15%
        CreateVolumeDiscountSetup(100, 15);

        // [WHEN] Discount is calculated
        Result := DiscountMgt.CalculateLineDiscount(SalesLine);

        // [THEN] Discount percentage is 15%
        Assert.AreEqual(15, Result, 'Volume discount not applied for qty >= 100');

        // [THEN] Line amount reflects the discount
        Assert.AreEqual(850, SalesLine."Line Amount",
            'Line amount should be 100 * 10 * (1 - 0.15) = 850');
    end;

    local procedure Initialize()
    begin
        if IsInitialized then
            exit;
        // One-time setup: number series, general setup, etc.
        IsInitialized := true;
    end;
}