rbxts-transformer-instances/test/transformer.test.ts

import * as ts from 'typescript';
import transformer from '../src/transformer';

function transpile(source: string): string {
    const program = ts.createProgram([], {});
    const result = ts.transpileModule(source, {
        compilerOptions: {
            target: ts.ScriptTarget.ESNext,
            module: ts.ModuleKind.CommonJS,
        },
        transformers: {
            before: [transformer(program) as ts.TransformerFactory<ts.SourceFile>]
        }
    });

    return result.outputText;
}

describe('rbxts-transformer-instances', () => {
    test('transforms new Part() to new Instance("Part")', () => {
        const source = `const part = new Part();`;
        const result = transpile(source);

        expect(result).toContain('const part = new Instance("Part")');
    });

    test('transforms new instances with arguments', () => {
        const source = `const model = new Model("MyModel");`;
        const result = transpile(source);

        expect(result).toContain('const model = new Instance("Model", "MyModel")');
    });

    test('preserves non-instance constructors', () => {
        const source = `const obj = new CustomClass();`;
        const result = transpile(source);

        expect(result).toContain('const obj = new CustomClass()');
    });

    test('handles multiple constructors in the same file', () => {
        const source = `
            const part = new Part();
            const obj = new CustomClass();
            const folder = new Folder("MyFolder");
        `;
        const result = transpile(source);

        expect(result).toContain('const part = new Instance("Part")');
        expect(result).toContain('const obj = new CustomClass()');
        expect(result).toContain('const folder = new Instance("Folder", "MyFolder")');
    });

    test('transforms instances in complex expressions', () => {
        const source = `
            function createParts() {
                return [new Part(), new Part(), new Model("MyModel")];
            }
        `;
        const result = transpile(source);

        expect(result).toContain('return [new Instance("Part"), new Instance("Part"), new Instance("Model", "MyModel")]');
    });
});