es6-block-scope.js

// -*- coding: utf-8 -*-
//  Copyright (C) 2014 Yusuke Suzuki <utatane.tea@gmail.com>
//
//  Redistribution and use in source and binary forms, with or without
//  modification, are permitted provided that the following conditions are met:
//
//    * Redistributions of source code must retain the above copyright
//      notice, this list of conditions and the following disclaimer.
//    * Redistributions in binary form must reproduce the above copyright
//      notice, this list of conditions and the following disclaimer in the
//      documentation and/or other materials provided with the distribution.
//
//  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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//  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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/* eslint-disable no-unused-expressions */

import { expect } from "chai";
import espree from "./util/espree.js";
import { getSupportedEcmaVersions } from "./util/ecma-version.js";
import { analyze } from "../lib/index.js";

describe("ES6 block scope", () => {
    it("let is materialized in ES6 block scope#1", () => {
        getSupportedEcmaVersions({ min: 6 }).forEach(ecmaVersion => {
            const ast = espree(`
                {
                    let i = 20;
                    i;
                }
            `);

            const scopeManager = analyze(ast, { ecmaVersion });

            expect(scopeManager.scopes).to.have.length(2); // Program and BlockStatement scope.

            let scope = scopeManager.scopes[0];

            expect(scope.type).to.be.equal("global");
            expect(scope.variables).to.have.length(0); // No variable in Program scope.

            scope = scopeManager.scopes[1];
            expect(scope.type).to.be.equal("block");
            expect(scope.variables).to.have.length(1); // `i` in block scope.
            expect(scope.variables[0].name).to.be.equal("i");
            expect(scope.references).to.have.length(2);
            expect(scope.references[0].identifier.name).to.be.equal("i");
            expect(scope.references[1].identifier.name).to.be.equal("i");
        });
    });

    it("function delaration is materialized in ES6 block scope", () => {
        getSupportedEcmaVersions({ min: 6 }).forEach(ecmaVersion => {
            const ast = espree(`
                {
                    function test() {
                    }
                    test();
                }
            `);

            const scopeManager = analyze(ast, { ecmaVersion });

            expect(scopeManager.scopes).to.have.length(3);

            let scope = scopeManager.scopes[0];

            expect(scope.type).to.be.equal("global");
            expect(scope.variables).to.have.length(0);

            scope = scopeManager.scopes[1];
            expect(scope.type).to.be.equal("block");
            expect(scope.variables).to.have.length(1);
            expect(scope.variables[0].name).to.be.equal("test");
            expect(scope.references).to.have.length(1);
            expect(scope.references[0].identifier.name).to.be.equal("test");

            scope = scopeManager.scopes[2];
            expect(scope.type).to.be.equal("function");
            expect(scope.variables).to.have.length(1);
            expect(scope.variables[0].name).to.be.equal("arguments");
            expect(scope.references).to.have.length(0);
        });
    });

    it("let is not hoistable#1", () => {
        getSupportedEcmaVersions({ min: 6 }).forEach(ecmaVersion => {
            const ast = espree(`
                var i = 42; (1)
                {
                    i;  // (2) ReferenceError at runtime.
                    let i = 20;  // (2)
                    i;  // (2)
                }
            `);

            const scopeManager = analyze(ast, { ecmaVersion });

            expect(scopeManager.scopes).to.have.length(2);

            const globalScope = scopeManager.scopes[0];

            expect(globalScope.type).to.be.equal("global");
            expect(globalScope.variables).to.have.length(1);
            expect(globalScope.variables[0].name).to.be.equal("i");
            expect(globalScope.references).to.have.length(1);

            const scope = scopeManager.scopes[1];

            expect(scope.type).to.be.equal("block");
            expect(scope.variables).to.have.length(1);
            expect(scope.variables[0].name).to.be.equal("i");
            expect(scope.references).to.have.length(3);
            expect(scope.references[0].resolved).to.be.equal(scope.variables[0]);
            expect(scope.references[1].resolved).to.be.equal(scope.variables[0]);
            expect(scope.references[2].resolved).to.be.equal(scope.variables[0]);
        });

    });

    it("let is not hoistable#2", () => {
        getSupportedEcmaVersions({ min: 6 }).forEach(ecmaVersion => {
            const ast = espree(`
                (function () {
                    var i = 42; // (1)
                    i;  // (1)
                    {
                        i;  // (3)
                        {
                            i;  // (2)
                            let i = 20;  // (2)
                            i;  // (2)
                        }
                        let i = 30;  // (3)
                        i;  // (3)
                    }
                    i;  // (1)
                }());
            `);

            const scopeManager = analyze(ast, { ecmaVersion });

            expect(scopeManager.scopes).to.have.length(4);

            const globalScope = scopeManager.scopes[0];

            expect(globalScope.type).to.be.equal("global");
            expect(globalScope.variables).to.have.length(0);
            expect(globalScope.references).to.have.length(0);

            let scope = scopeManager.scopes[1];

            expect(scope.type).to.be.equal("function");
            expect(scope.variables).to.have.length(2);
            expect(scope.variables[0].name).to.be.equal("arguments");
            expect(scope.variables[1].name).to.be.equal("i");
            const v1 = scope.variables[1];

            expect(scope.references).to.have.length(3);
            expect(scope.references[0].resolved).to.be.equal(v1);
            expect(scope.references[1].resolved).to.be.equal(v1);
            expect(scope.references[2].resolved).to.be.equal(v1);

            scope = scopeManager.scopes[2];
            expect(scope.type).to.be.equal("block");
            expect(scope.variables).to.have.length(1);
            expect(scope.variables[0].name).to.be.equal("i");
            const v3 = scope.variables[0];

            expect(scope.references).to.have.length(3);
            expect(scope.references[0].resolved).to.be.equal(v3);
            expect(scope.references[1].resolved).to.be.equal(v3);
            expect(scope.references[2].resolved).to.be.equal(v3);

            scope = scopeManager.scopes[3];
            expect(scope.type).to.be.equal("block");
            expect(scope.variables).to.have.length(1);
            expect(scope.variables[0].name).to.be.equal("i");
            const v2 = scope.variables[0];

            expect(scope.references).to.have.length(3);
            expect(scope.references[0].resolved).to.be.equal(v2);
            expect(scope.references[1].resolved).to.be.equal(v2);
            expect(scope.references[2].resolved).to.be.equal(v2);
        });
    });
});

// vim: set sw=4 ts=4 et tw=80 :