loom/test/transform.test.mjs

import transform from '../src/transform.mjs';

describe("transform", () => {
	const ast_emptyDiv = {
		"type": "root",
		"children": [
			{
				"type": "element",
				"tagName": "div",
				"properties": {},
				"children": [],
			},
		],
	};

	it("should import transform()", () => {
		expect(transform).toBeDefined();
	});

	it("should throw an error if there's no AST", () => {
		expect(transform).toBeDefined();
		expect(() => transform()).toThrow();
	});

	it("should act as an identity function if there are no tx fxns", () => {
		expect(transform(ast_emptyDiv)).toEqual({
			"type": "root",
			"children": [
				{
					"type": "element",
					"tagName": "div",
					"properties": {},
					"children": [],
				},
			],
		});
	});

	it("should leave the ast untouched for undefined", () => {
		expect(transform(ast_emptyDiv, () => undefined)).toEqual({
			"type": "root",
			"children": [
				{
					"type": "element",
					"tagName": "div",
					"properties": {},
					"children": [],
				},
			],
		});
	});

	it("should remove the node for null", () => {
		expect(transform(ast_emptyDiv, () => null)).toEqual({
			"type": "root",
			"children": [],
		});
	});

	it("should barf if non-AST is returned", () => {
		expect(() => {transform(ast_emptyDiv, () => "pigs!")}).toThrow();
	});

	it("should replace old nodes with transformed nodes", () => {
		expect(transform(
			ast_emptyDiv,
			() => ({type: "element", tagName: "div", children: []})
		)).toEqual({
			"type": "root",
			"children": [
				{
					type: "element",
					tagName: "div",
					children: [],
				},
			],
		});
	});

	it("should transform nodes anywhere in the child list", () => {
		expect(transform(
			{
				"type": "root",
				"children": [
					{
						type: "element",
						tagName: "div",
						children: [],
					},
					{
						type: "element",
						tagName: "span",
						children: [],
					},
				],
			},
			(node) => {
				if (node.tagName === "span") {
					return {
						type: "element",
						tagName: "p",
						children: [],
					};
				}
			}
		)).toEqual({
			"type": "root",
			"children": [
				{
					type: "element",
					tagName: "div",
					children: [],
				},
				{
					type: "element",
					tagName: "p",
					children: [],
				},
			],
		});
	});
	it("should delete nodes anywhere in the child list", () => {
		expect(transform(
			{
				"type": "root",
				"children": [
					{
						type: "element",
						tagName: "div",
						children: [],
					},
					{
						type: "element",
						tagName: "span",
						children: [],
					},
				],
			},
			(node) => {
				if (node.tagName === "span") {
					return null;
				}
			}
		)).toEqual({
			"type": "root",
			"children": [
				{
					type: "element",
					tagName: "div",
					children: [],
				},
			],
		});
	});

	it("should stop transforming after a transformer returns null", () => {
		expect(transform(
			ast_emptyDiv,
			() => null,
			() => ({type: "element", tagName: "div", children: []})
		)).toEqual({
			"type": "root",
			"children": [],
		});
	});

	it("should handle multiple tx fxns", () => {
		const output = transform(ast_emptyDiv, () => {return}, () => null);
		expect(output).toEqual({
			type: "root",
			children: [],
		});
	});

});