forked from babel/babel
/
traverse.js
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/
traverse.js
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import { parse } from "@babel/parser";
import * as t from "@babel/types";
import _traverse from "../lib/index.js";
const traverse = _traverse.default;
describe("traverse", function () {
const code = `
var foo = "bar";
this.test = "wow";
`;
const ast = parse(code);
const program = ast.program;
const body = program.body;
it("traverse replace", function () {
const replacement = {
type: "StringLiteral",
value: "foo",
};
const ast2 = JSON.parse(JSON.stringify(program));
traverse(ast2, {
enter: function (path) {
if (path.node.type === "ThisExpression") path.replaceWith(replacement);
},
});
expect(ast2.body[1].expression.left.object).toBe(replacement);
});
it("traverse", function () {
const expected = [
body[0],
body[0].declarations[0],
body[0].declarations[0].id,
body[0].declarations[0].init,
body[1],
body[1].expression,
body[1].expression.left,
body[1].expression.left.object,
body[1].expression.left.property,
body[1].expression.right,
];
const actual = [];
traverse(program, {
enter: function (path) {
actual.push(path.node);
},
});
expect(actual).toEqual(expected);
});
it("traverse falsy parent", function () {
traverse(null, {
enter: function () {
throw new Error("should not be ran");
},
});
});
it("traverse denylistTypes", function () {
const expected = [
body[0],
body[0].declarations[0],
body[0].declarations[0].id,
body[0].declarations[0].init,
body[1],
body[1].expression,
body[1].expression.right,
];
const actual = [];
traverse(program, {
denylist: ["MemberExpression"],
enter: function (path) {
actual.push(path.node);
},
});
expect(actual).toEqual(expected);
});
it("hasType", function () {
expect(traverse.hasType(ast, "ThisExpression")).toBeTruthy();
expect(
traverse.hasType(ast, "ThisExpression", ["AssignmentExpression"]),
).toBeFalsy();
expect(traverse.hasType(ast, "ThisExpression")).toBeTruthy();
expect(traverse.hasType(ast, "Program")).toBeTruthy();
expect(
traverse.hasType(ast, "ThisExpression", ["MemberExpression"]),
).toBeFalsy();
expect(traverse.hasType(ast, "ThisExpression", ["Program"])).toBeFalsy();
expect(traverse.hasType(ast, "ArrowFunctionExpression")).toBeFalsy();
});
it("clearCache", function () {
const paths = [];
const scopes = [];
traverse(ast, {
enter(path) {
scopes.push(path.scope);
paths.push(path);
path.stop();
},
});
traverse.cache.clear();
const paths2 = [];
const scopes2 = [];
traverse(ast, {
enter(path) {
scopes2.push(path.scope);
paths2.push(path);
path.stop();
},
});
scopes2.forEach(function (_, i) {
expect(scopes[i]).not.toBe(scopes2[i]);
expect(paths[i]).not.toBe(paths2[i]);
});
});
it("clearPath", function () {
const paths = [];
traverse(ast, {
enter(path) {
paths.push(path);
},
});
traverse.cache.clearPath();
const paths2 = [];
traverse(ast, {
enter(path) {
paths2.push(path);
},
});
paths2.forEach(function (p, i) {
expect(p).not.toBe(paths[i]);
});
});
it("clearScope", function () {
const scopes = [];
traverse(ast, {
enter(path) {
scopes.push(path.scope);
path.stop();
},
});
traverse.cache.clearScope();
const scopes2 = [];
traverse(ast, {
enter(path) {
scopes2.push(path.scope);
path.stop();
},
});
scopes2.forEach(function (p, i) {
expect(p).not.toBe(scopes[i]);
});
});
describe("path.skip()", function () {
it("replaced paths can be skipped", function () {
const ast = parse("id");
let skipped;
traverse(ast, {
noScope: true,
Identifier(path) {
path.replaceWith(t.numericLiteral(0));
path.skip();
skipped = true;
},
NumericLiteral() {
skipped = false;
},
});
expect(skipped).toBe(true);
});
// Skipped: see the comment in the `NodePath.requeue` method.
// eslint-disable-next-line jest/no-disabled-tests
it.skip("skipped and requeued paths should be visited", function () {
const ast = parse("id");
let visited = false;
traverse(ast, {
noScope: true,
Identifier(path) {
path.replaceWith(t.numericLiteral(0));
path.skip();
path.requeue();
},
NumericLiteral() {
visited = true;
},
});
expect(visited).toBe(true);
});
});
describe("path.visit()", () => {
it("should preserve traversal context after enter hook is executed", () => {
const ast = parse("{;}");
// The test initiates a sub-traverse from program. When the `enter` hook of BlockStatement
// is called, the unshiftContainer will change the traversal context of the BlockStatement
// to the one of Program which has an EmptyStatement visitor. If the traversal context
// is not restored after the `enter` hook is executed, the `EmptyStatement` visitor will
// be run twice: one in the sub-traverse and the other in the top level traverse.
let emptyStatementVisitedCounter = 0;
traverse(ast, {
noScope: true,
Program(path) {
path.traverse({
noScope: true,
BlockStatement: {
enter(path) {
path.parentPath.unshiftContainer("body", [t.numericLiteral(0)]);
},
},
});
},
EmptyStatement() {
++emptyStatementVisitedCounter;
},
});
expect(emptyStatementVisitedCounter).toBe(1);
});
it("should preserve traversal context after visitor is executed", () => {
const ast = parse("{;}");
// The test initiates a sub-traverse from program. During the BlockStatement is traversed,
// the EmptyStatement visitor will be called and the unshiftContainer will change the
// traversal context of the BlockStatement to that of Program which has an EmptyStatement
// visitor. If the traversal context is not restored after `enter` hook is executed,
// the `BlockStatement:exit` visitor will be run twice: one in the sub-traverse and the other
// in the top level traverse.
let blockStatementVisitedCounter = 0;
traverse(ast, {
noScope: true,
Program(path) {
path.traverse({
noScope: true,
EmptyStatement: {
enter(path) {
path.parentPath.parentPath.unshiftContainer("body", [
t.numericLiteral(0),
]);
},
},
});
},
BlockStatement: {
exit() {
++blockStatementVisitedCounter;
},
},
});
expect(blockStatementVisitedCounter).toBe(1);
});
});
describe("path.stop()", () => {
it("should stop the traversal when a grand child is stopped", () => {
const ast = parse("f;g;");
let visitedCounter = 0;
traverse(ast, {
noScope: true,
Identifier(path) {
visitedCounter += 1;
path.stop();
},
});
expect(visitedCounter).toBe(1);
});
it("can be reverted in the exit listener of the parent whose child is stopped", () => {
const ast = parse("f;g;");
let visitedCounter = 0;
traverse(ast, {
noScope: true,
Identifier(path) {
visitedCounter += 1;
path.stop();
},
ExpressionStatement: {
exit(path) {
path.shouldStop = false;
path.shouldSkip = false;
},
},
});
expect(visitedCounter).toBe(2);
});
it("should not affect root traversal", () => {
const ast = parse("f;g;");
let visitedCounter = 0;
let programShouldStop;
traverse(ast, {
noScope: true,
Program(path) {
path.traverse({
noScope: true,
Identifier(path) {
visitedCounter += 1;
path.stop();
},
});
programShouldStop = path.shouldStop;
},
});
expect(visitedCounter).toBe(1);
expect(programShouldStop).toBe(false);
});
});
});