Add mocks to NodeJS "timers" module (#467)

* add tests * implement mocking timers module * improve tests * move tests to fake-timers-test.js * rename timersModuleMocks to timersModuleMethods * Add notes about touching NodeJS timers module to README.md
sinonjs · May 18, 2023 · a111a71 · a111a71
1 parent dbdf02a
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diff --git a/README.md b/README.md
@@ -67,6 +67,7 @@ clock instance, not the browser's internals.
 
 Calling `install` with no arguments achieves this. You can call `uninstall`
 later to restore things as they were again.
+Note that in NodeJS also the [timers](https://nodejs.org/api/timers.html) module will receive fake timers when using global scope.
 
 ```js
 // In the browser distribution, a global `FakeTimers` is already available
@@ -146,7 +147,9 @@ The `loopLimit` argument sets the maximum number of timers that will be run when
 
 ### `var clock = FakeTimers.install([config])`
 
-Installs FakeTimers using the specified config (otherwise with epoch `0` on the global scope). The following configuration options are available
+Installs FakeTimers using the specified config (otherwise with epoch `0` on the global scope).
+Note that in NodeJS also the [timers](https://nodejs.org/api/timers.html) module will receive fake timers when using global scope.
+The following configuration options are available
 
 | Parameter                        | Type        | Default                                                                                                                                                                                                                        | Description                                                                                                                                                                                                                                                                                  |
 | -------------------------------- | ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

diff --git a/src/fake-timers-src.js b/src/fake-timers-src.js
@@ -1,6 +1,14 @@
 "use strict";
 
 const globalObject = require("@sinonjs/commons").global;
+let timersModule;
+if (typeof require === "function" && typeof module === "object") {
+    try {
+        timersModule = require("timers");
+    } catch (e) {
+        // ignored
+    }
+}
 
 /**
  * @typedef {object} IdleDeadline
@@ -85,6 +93,7 @@ const globalObject = require("@sinonjs/commons").global;
  * @property {function(): void} uninstall Uninstall the clock.
  * @property {Function[]} methods - the methods that are faked
  * @property {boolean} [shouldClearNativeTimers] inherited from config
+ * @property {{methodName:string, original:any}[] | undefined} timersModuleMethods
  */
 /* eslint-enable jsdoc/require-property-description */
 
@@ -886,6 +895,12 @@ function withGlobal(_global) {
                     }
                 }
             }
+            if (clock.timersModuleMethods !== undefined) {
+                for (let j = 0; j < clock.timersModuleMethods.length; j++) {
+                    const entry = clock.timersModuleMethods[j];
+                    timersModule[entry.methodName] = entry.original;
+                }
+            }
         }
 
         if (config.shouldAdvanceTime === true) {
@@ -1733,7 +1748,9 @@ function withGlobal(_global) {
                 );
             }
         }
-
+        if (_global === globalObject && timersModule) {
+            clock.timersModuleMethods = [];
+        }
         for (i = 0, l = clock.methods.length; i < l; i++) {
             const nameOfMethodToReplace = clock.methods[i];
             if (nameOfMethodToReplace === "hrtime") {
@@ -1753,6 +1770,18 @@ function withGlobal(_global) {
             } else {
                 hijackMethod(_global, nameOfMethodToReplace, clock);
             }
+            if (
+                clock.timersModuleMethods !== undefined &&
+                timersModule[nameOfMethodToReplace]
+            ) {
+                const original = timersModule[nameOfMethodToReplace];
+                clock.timersModuleMethods.push({
+                    methodName: nameOfMethodToReplace,
+                    original: original,
+                });
+                timersModule[nameOfMethodToReplace] =
+                    _global[nameOfMethodToReplace];
+            }
         }
 
         return clock;

diff --git a/test/fake-timers-test.js b/test/fake-timers-test.js
@@ -21,6 +21,16 @@ const {
     utilPromisifyAvailable,
 } = require("./helpers/setup-tests");
 
+var timersModule;
+
+if (typeof require === "function" && typeof module === "object") {
+    try {
+        timersModule = require("timers");
+    } catch (e) {
+        // ignored
+    }
+}
+
 describe("FakeTimers", function () {
     describe("setTimeout", function () {
         beforeEach(function () {
@@ -4664,6 +4674,137 @@ describe("FakeTimers", function () {
             assert.isFalse(stub.called);
         });
     });
+    describe("Node timers module", function () {
+        before(function () {
+            if (!timersModule) {
+                this.skip();
+            }
+        });
+
+        /**
+         * Returns elements that are present in both lists.
+         *
+         * @function
+         * @template E
+         * @param {E[]} [list1]
+         * @param {E[]} [list2]
+         * @return {E[]}
+         */
+        function getIntersection(list1, list2) {
+            return list1.filter((value) => list2.indexOf(value) !== -1);
+        }
+
+        /**
+         * Get property names and original values from timers module.
+         *
+         * @function
+         * @param {string[]} [toFake]
+         * @return {{propertyName: string, originalValue: any}[]}
+         */
+        function getOriginals(toFake) {
+            return toFake.map((propertyName) => ({
+                propertyName,
+                originalValue: timersModule[propertyName],
+            }));
+        }
+
+        afterEach(function () {
+            if (this.clock) {
+                this.clock.uninstall();
+                delete this.clock;
+            }
+        });
+
+        it("should install all timers", function () {
+            const toFake = getIntersection(
+                Object.getOwnPropertyNames(timersModule),
+                Object.getOwnPropertyNames(FakeTimers.timers)
+            );
+            const originals = getOriginals(toFake);
+
+            this.clock = FakeTimers.install();
+
+            for (const { propertyName, originalValue } of originals) {
+                refute.same(timersModule[propertyName], originalValue);
+            }
+        });
+
+        it("should uninstall all timers", function () {
+            const toFake = getIntersection(
+                Object.getOwnPropertyNames(timersModule),
+                Object.getOwnPropertyNames(FakeTimers.timers)
+            );
+            const originals = getOriginals(toFake);
+
+            this.clock = FakeTimers.install();
+            this.clock.uninstall();
+
+            for (const { propertyName, originalValue } of originals) {
+                assert.same(timersModule[propertyName], originalValue);
+            }
+        });
+
+        it("should have synchronized clock with globalObject", function () {
+            this.clock = FakeTimers.install();
+
+            const globalStub = sinon.stub();
+            const timersStub = sinon.stub();
+
+            timersModule.setTimeout(timersStub, 5);
+            setTimeout(globalStub, 5);
+            this.clock.tick(5);
+            assert(globalStub.calledOnce);
+            assert(timersStub.calledOnce);
+        });
+
+        it("fakes and resets provided methods", function () {
+            const toFake = ["setTimeout", "Date"];
+            const originals = getOriginals(toFake);
+            this.clock = FakeTimers.install({ toFake });
+
+            for (const { propertyName, originalValue } of originals) {
+                if (originalValue === undefined) {
+                    assert.same(timersModule[propertyName], originalValue);
+                } else {
+                    refute.same(timersModule[propertyName], originalValue);
+                }
+            }
+        });
+
+        it("resets faked methods", function () {
+            const toFake = ["setTimeout", "Date"];
+            const originals = getOriginals(toFake);
+
+            this.clock = FakeTimers.install({ toFake });
+            this.clock.uninstall();
+
+            for (const { propertyName, originalValue } of originals) {
+                assert.same(timersModule[propertyName], originalValue);
+            }
+        });
+
+        it("does not fake methods not provided", function () {
+            const toFake = ["setTimeout", "Date"];
+            const notToFake = ["clearTimeout", "setInterval", "clearInterval"];
+            const originals = getOriginals(notToFake);
+
+            this.clock = FakeTimers.install({ toFake });
+
+            for (const { propertyName, originalValue } of originals) {
+                assert.same(timersModule[propertyName], originalValue);
+            }
+        });
+
+        it("does not fake when installing on custom global object", function () {
+            const original = timersModule.setTimeout;
+            this.clock = FakeTimers.withGlobal({
+                Date: Date,
+                setTimeout: sinon.fake(),
+                clearTimeout: sinon.fake(),
+            }).install();
+            assert.same(timersModule.setTimeout, original);
+        });
+    });
 });
 
 describe("loop limit stack trace", function () {