create_question.md

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Questions and expectations

Testla helps you model your test scenarios from the perspective of actors performing activities to accomplish their goals. Assertions follow this same consistent approach, with any assertions expressed using the interaction to ask.

Implementing custom questions

You can also implement custom questions when needed. To do that, take a look on the following code.

import { expect } from '@playwright/test';
import { Question } from '@testla/screenplay-playwright';

export class Entity extends Question<boolean> {
    private payload: any;

    private checkMode: 'has' | 'hasNot';

    private constructor(checkMode: 'has' | 'hasNot') {
        super();
        this.checkMode = checkMode;
    }

    public async answeredBy(): Promise<boolean> {
        const { obj, attribute, value } = this.payload;
        const attributeFound = obj[attribute] === value;
        
        expect(attributeFound).toBe(this.checkMode === 'has');
        return Promise.resolve(true);
    }

    static get has() {
        return new Entity('has');
    }

    static get hasNot() {
        return new Entity('hasNot');
    }

    public attributeValue(obj: any, attribute: string, value: any): Entity {
        this.payload = { obj, attribute, value };
        return this;
    }
}

In Detail

Let's break down the above code for implementing a custom question. The Entity class is a custom question that extends Question<boolean>. It's designed to check whether a specific attribute of an object has a certain value. The Entity class has a private constructor that takes a parameter checkMode (has or hasNot). This parameter determines whether the question is checking for a positive condition (has) or a negative condition (hasNot).

The answeredBy method is an abstract method from the Question class that needs to be implemented. It performs the actual logic of the question. It checks whether the specified attribute of the object matches the expected value based on the checkMode. Under the hood we use Playwright's expect to assert if the condition is met.

The Entity class has static factory methods called has and hasNot that create instances of Entity with the corresponding checkMode.

The attributeValue method sets the payload with the object, attribute and value that will be used in the answeredBy method. This method allows setting the parameters for the question in a fluent manner.

This custom question, demonstrates how you can implement reusable and expressive questions in the Screenplay Pattern. It provides a flexible way to check whether a certain attribute of an object has a specific value and supports both positive and negative assertions.

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