Write the utility acceptance contract — Boundary detective

PART I

Warm-up

Reconnect with a useful idea before starting write the utility acceptance contract. In one or two sentences, describe the input, output or host boundary from the previous exercise that this lesson builds on. If you are arriving directly, skim the worked example first; there is no locked prerequisite.

A rough note is enough. You can revise it after the example.

PART II

Instruction & guided example

Choose a boundary case that can fail the design

An acceptance contract makes a feature claim falsifiable. A feature description becomes reviewable when it names supplied inputs, required effects, visible outcomes and failure boundaries. Separate what source vocabulary expresses, what an exercise host must guarantee, and what a paper trace merely predicts. Public practice can be completed manually; it does not certify code execution.

Requirement: title must contain at least one non-space character after the specified normalization step. Cases are Help, empty string, and three spaces. The host has not supplied any automatic normalization.

For each requirement, choose an ordinary case and a case that would expose a plausible wrong implementation. Name the expected artifact or state change and the evidence that would establish it. A list of attractive screens is not a substitute for observable behavior. Worked case: Help passes. Empty fails. Spaces fail only if the application explicitly performs or obtains the stated normalization before checking. Counting raw characters alone incorrectly accepts the spaces case.

Compare the tempting alternative: Testing only long normal titles can leave a broken required-field rule undiscovered. Assuming a host trims text without a contract hides where the rule is implemented.

Worked reasoning and supplied artifact

// Paper trace / supplied exercise-host contract; no execution claimed.
// Requirement: title must contain at least one non-space character after the specified normalization step. Cases are Help, empty string, and three spaces. The host has not supplied any automatic normalization.
// Help passes. Empty fails. Spaces fail only if the application explicitly performs or obtains the stated normalization before checking. Counting raw characters alone incorrectly accepts the spaces case.

Illustrative example from the proposed WillowScript design. The language and WUIX/WMATH/WDB/WAUDIO/WTMP services are not implemented in the supplied source. This site has no interpreter, VM or native host and does not execute or certify the snippet.

Try the guided change

Reconstruct the supplied worked case first: list its inputs, intermediate decisions and final artifact. Compare each row with the explanation and identify exactly where the rejected alternative fails. Then use the changed inputs in Part IV for independent work.

• Write the supplied inputs and initial state before following the example.
• Reconstruct each intermediate calculation or host decision, then compare with the worked artifact.
• Explain why the contrasting alternative fails before attempting the changed inputs in Part IV.

PART III

Take a breather

Step back after the guided example. Look away from the screen, stretch, or reread your prediction. This is an optional learning pause, not a timer or an assessment gate.

When you return, try to name the lesson’s key idea without copying its wording. If that feels difficult, return to Part II and trace one line rather than restarting the entire lesson.

PART IV

Independent practice

Project context: Event-driven team utility. Build a small, understandable change around write the utility acceptance contract.

Write raw input, normalized input and decision columns for the cases, then add a title with leading spaces around Help.

What to produce

A four-row normalization/validation table and a responsible-layer note.

• State the intended behavior in a sentence before editing.
• Use only source-backed syntax and the host services whose contract you have been given.
• Record a normal case and a boundary or unavailable-resource case.
• Label hand predictions separately from anything actually measured in a supplied toolchain.

Syntax colors are a reading aid, not a compiler. The line you are editing stays uncolored until you move to a different line; capitalization is never changed. Drafts stay on this browser and code is not executed.

import wuix.widget;
import app;
domain Workspace {
    const application = Application({
        name: "Workspace",
        window: { title: "Dashboard", size: [1280, 800] },
        events: {
            "app.ready": fnc() -> void { console.log("Ready"); }
        }
    });
}

PART V

Self-check

Use this check to notice what to revisit. It does not award a private course grade, block another page or claim to verify compiled code. Every answer has a learning explanation.

You may keep exploring even if you are unsure. Use the hint, compare the trace, and revise your explanation.

PART VI

Recap & small task

Bring the idea back to the mod feature you are building. A useful recap connects the mechanism to a decision you can make in your own code.

• Choose a boundary case that can fail the design
• Write raw input, normalized input and decision columns for the cases, then add a title with leading spaces around Help.
• Separate source-backed behavior, host requirements and untested predictions.

One small recap task

State who must own the normalization step.

This marks your personal practice record only. It is not a certification or an official workspace assessment.