jest-environment-node-single-context/lib/main/SingleContextNodeEnvironment.js

Jest environment for Node with single context

"use strict";
/*
 * Copyright (C) 2020 Klaus Reimer <k@ailis.de>
 * See LICENSE.md for licensing information.
 */
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
const vm_1 = require("vm");
const jest_environment_node_1 = __importDefault(require("jest-environment-node"));
const fake_timers_1 = require("@jest/fake-timers");
/** Special context which is handled specially in the hacked runInContext method below */
const singleContexts = new WeakSet();
/** Remembered original runInContext method. */
const origRunInContext = vm_1.Script.prototype.runInContext;
/**
 * Ugly hack to allow Jest to just use a single Node VM context. The Jest code in question is in a large private
 * method of the standard Jest runtime and it would be a lot of code-copying to create a custom runtime which
 * replaces the script run code. So we hack into the `script.runInContext` method instead to redirect it to
 * `script.runInThisContext` for vm contexts recorded in `singleContexts` set.
 */
vm_1.Script.prototype.runInContext = function (context, options) {
    if (singleContexts.has(context)) {
        return this.runInThisContext(options);
    }
    else {
        return origRunInContext.call(this, context, options);
    }
};
const timerIdToRef = (id) => ({
    id,
    ref() {
        return this;
    },
    unref() {
        return this;
    },
});
const timerRefToId = (timer) => timer === null || timer === void 0 ? void 0 : timer.id;
class SingleContextNodeEnvironment extends jest_environment_node_1.default {
    constructor(config, context) {
        super(config, context);
        // Use shared global environment for all tests
        this.global = global;
        // Recreate context using the shared global environment. This fixes the environment for ESM module stuff of Jest (which doesn't just use the context
        // for `script.runInContext`) but a few type mismatches are still there unfortunately. For CJS mode this is irrelevant because calls for
        // `script.runInContext` using this context are always redirected to `script.runInThisContext`. All this would not be necessary if we could just get
        // the CURRENT vm context. But Node API doesn't allow that.
        this.context = (0, vm_1.createContext)(global);
        if (this.context != null) {
            // Record the VM context of this environment so the hacked `script.runInContext` redirects the call to `script.runInThisContext` for this context.
            singleContexts.add(this.context);
        }
        // Install fake timers again, this time with shared global environment
        this.fakeTimers = new fake_timers_1.LegacyFakeTimers({
            config: config.projectConfig,
            global,
            moduleMocker: this.moduleMocker,
            timerConfig: {
                idToRef: timerIdToRef,
                refToId: timerRefToId
            }
        });
        this.fakeTimersModern = new fake_timers_1.ModernFakeTimers({
            config: config.projectConfig,
            global
        });
    }
}
module.exports = SingleContextNodeEnvironment;
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