Promise-race-dependent-promises.js

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// Promise.race(...) may add a dummy PromiseReaction which is only used for the

// debugger.

//

// See BlockOnPromise when called from PerformPromiseRace for when this dummy

// reaction is created.

var g = newGlobal({newCompartment: true});

var dbg = new Debugger();

var gw = dbg.addDebuggee(g);

function test(withFastPath) {

    g.eval(`

        function newPromiseCapability() {

            var resolve, reject, promise = new Promise(function(r1, r2) {

                resolve = r1;

                reject = r2;

});

            return {promise, resolve, reject};

        var {promise: alwaysPending} = newPromiseCapability();

        if (!${withFastPath}) {

            // Disable the BlockOnPromise fast path by giving |alwaysPending| a

            // non-default "then" function property. This will ensure the dummy

            // reaction is created.

            alwaysPending.then = function() {};

        var result = Promise.race([alwaysPending]);

`);

    var alwaysPending = gw.makeDebuggeeValue(g.alwaysPending);

    var result = gw.makeDebuggeeValue(g.result);

    assertEq(alwaysPending.promiseDependentPromises.length, 1);

    assertEq(alwaysPending.promiseDependentPromises[0], result);

    assertEq(result.promiseDependentPromises.length, 0);

// No dummy reaction created when the fast path is taken.

test(true);

// Dummy reaction is created when we can't take the fast path.

test(false);