feat(vanilla): add testing infrastructure and tests (NK-wjnczv)

1 files changed, 425 insertions, 0 deletions

diff --git a/vanilla/node_modules/undici/lib/util/timers.js b/vanilla/node_modules/undici/lib/util/timers.js
new file mode 100644
index 0000000..14984d4
--- /dev/null
+++ b/vanilla/node_modules/undici/lib/util/timers.js
@@ -0,0 +1,425 @@
+'use strict'
+
+/**
+ * This module offers an optimized timer implementation designed for scenarios
+ * where high precision is not critical.
+ *
+ * The timer achieves faster performance by using a low-resolution approach,
+ * with an accuracy target of within 500ms. This makes it particularly useful
+ * for timers with delays of 1 second or more, where exact timing is less
+ * crucial.
+ *
+ * It's important to note that Node.js timers are inherently imprecise, as
+ * delays can occur due to the event loop being blocked by other operations.
+ * Consequently, timers may trigger later than their scheduled time.
+ */
+
+/**
+ * The fastNow variable contains the internal fast timer clock value.
+ *
+ * @type {number}
+ */
+let fastNow = 0
+
+/**
+ * RESOLUTION_MS represents the target resolution time in milliseconds.
+ *
+ * @type {number}
+ * @default 1000
+ */
+const RESOLUTION_MS = 1e3
+
+/**
+ * TICK_MS defines the desired interval in milliseconds between each tick.
+ * The target value is set to half the resolution time, minus 1 ms, to account
+ * for potential event loop overhead.
+ *
+ * @type {number}
+ * @default 499
+ */
+const TICK_MS = (RESOLUTION_MS >> 1) - 1
+
+/**
+ * fastNowTimeout is a Node.js timer used to manage and process
+ * the FastTimers stored in the `fastTimers` array.
+ *
+ * @type {NodeJS.Timeout}
+ */
+let fastNowTimeout
+
+/**
+ * The kFastTimer symbol is used to identify FastTimer instances.
+ *
+ * @type {Symbol}
+ */
+const kFastTimer = Symbol('kFastTimer')
+
+/**
+ * The fastTimers array contains all active FastTimers.
+ *
+ * @type {FastTimer[]}
+ */
+const fastTimers = []
+
+/**
+ * These constants represent the various states of a FastTimer.
+ */
+
+/**
+ * The `NOT_IN_LIST` constant indicates that the FastTimer is not included
+ * in the `fastTimers` array. Timers with this status will not be processed
+ * during the next tick by the `onTick` function.
+ *
+ * A FastTimer can be re-added to the `fastTimers` array by invoking the
+ * `refresh` method on the FastTimer instance.
+ *
+ * @type {-2}
+ */
+const NOT_IN_LIST = -2
+
+/**
+ * The `TO_BE_CLEARED` constant indicates that the FastTimer is scheduled
+ * for removal from the `fastTimers` array. A FastTimer in this state will
+ * be removed in the next tick by the `onTick` function and will no longer
+ * be processed.
+ *
+ * This status is also set when the `clear` method is called on the FastTimer instance.
+ *
+ * @type {-1}
+ */
+const TO_BE_CLEARED = -1
+
+/**
+ * The `PENDING` constant signifies that the FastTimer is awaiting processing
+ * in the next tick by the `onTick` function. Timers with this status will have
+ * their `_idleStart` value set and their status updated to `ACTIVE` in the next tick.
+ *
+ * @type {0}
+ */
+const PENDING = 0
+
+/**
+ * The `ACTIVE` constant indicates that the FastTimer is active and waiting
+ * for its timer to expire. During the next tick, the `onTick` function will
+ * check if the timer has expired, and if so, it will execute the associated callback.
+ *
+ * @type {1}
+ */
+const ACTIVE = 1
+
+/**
+ * The onTick function processes the fastTimers array.
+ *
+ * @returns {void}
+ */
+function onTick () {
+  /**
+   * Increment the fastNow value by the TICK_MS value, despite the actual time
+   * that has passed since the last tick. This approach ensures independence
+   * from the system clock and delays caused by a blocked event loop.
+   *
+   * @type {number}
+   */
+  fastNow += TICK_MS
+
+  /**
+   * The `idx` variable is used to iterate over the `fastTimers` array.
+   * Expired timers are removed by replacing them with the last element in the array.
+   * Consequently, `idx` is only incremented when the current element is not removed.
+   *
+   * @type {number}
+   */
+  let idx = 0
+
+  /**
+   * The len variable will contain the length of the fastTimers array
+   * and will be decremented when a FastTimer should be removed from the
+   * fastTimers array.
+   *
+   * @type {number}
+   */
+  let len = fastTimers.length
+
+  while (idx < len) {
+    /**
+     * @type {FastTimer}
+     */
+    const timer = fastTimers[idx]
+
+    // If the timer is in the ACTIVE state and the timer has expired, it will
+    // be processed in the next tick.
+    if (timer._state === PENDING) {
+      // Set the _idleStart value to the fastNow value minus the TICK_MS value
+      // to account for the time the timer was in the PENDING state.
+      timer._idleStart = fastNow - TICK_MS
+      timer._state = ACTIVE
+    } else if (
+      timer._state === ACTIVE &&
+      fastNow >= timer._idleStart + timer._idleTimeout
+    ) {
+      timer._state = TO_BE_CLEARED
+      timer._idleStart = -1
+      timer._onTimeout(timer._timerArg)
+    }
+
+    if (timer._state === TO_BE_CLEARED) {
+      timer._state = NOT_IN_LIST
+
+      // Move the last element to the current index and decrement len if it is
+      // not the only element in the array.
+      if (--len !== 0) {
+        fastTimers[idx] = fastTimers[len]
+      }
+    } else {
+      ++idx
+    }
+  }
+
+  // Set the length of the fastTimers array to the new length and thus
+  // removing the excess FastTimers elements from the array.
+  fastTimers.length = len
+
+  // If there are still active FastTimers in the array, refresh the Timer.
+  // If there are no active FastTimers, the timer will be refreshed again
+  // when a new FastTimer is instantiated.
+  if (fastTimers.length !== 0) {
+    refreshTimeout()
+  }
+}
+
+function refreshTimeout () {
+  // If the fastNowTimeout is already set and the Timer has the refresh()-
+  // method available, call it to refresh the timer.
+  // Some timer objects returned by setTimeout may not have a .refresh()
+  // method (e.g. mocked timers in tests).
+  if (fastNowTimeout?.refresh) {
+    fastNowTimeout.refresh()
+    // fastNowTimeout is not instantiated yet or refresh is not availabe,
+    // create a new Timer.
+  } else {
+    clearTimeout(fastNowTimeout)
+    fastNowTimeout = setTimeout(onTick, TICK_MS)
+    // If the Timer has an unref method, call it to allow the process to exit,
+    // if there are no other active handles. When using fake timers or mocked
+    // environments (like Jest), .unref() may not be defined,
+    fastNowTimeout?.unref()
+  }
+}
+
+/**
+ * The `FastTimer` class is a data structure designed to store and manage
+ * timer information.
+ */
+class FastTimer {
+  [kFastTimer] = true
+
+  /**
+   * The state of the timer, which can be one of the following:
+   * - NOT_IN_LIST (-2)
+   * - TO_BE_CLEARED (-1)
+   * - PENDING (0)
+   * - ACTIVE (1)
+   *
+   * @type {-2|-1|0|1}
+   * @private
+   */
+  _state = NOT_IN_LIST
+
+  /**
+   * The number of milliseconds to wait before calling the callback.
+   *
+   * @type {number}
+   * @private
+   */
+  _idleTimeout = -1
+
+  /**
+   * The time in milliseconds when the timer was started. This value is used to
+   * calculate when the timer should expire.
+   *
+   * @type {number}
+   * @default -1
+   * @private
+   */
+  _idleStart = -1
+
+  /**
+   * The function to be executed when the timer expires.
+   * @type {Function}
+   * @private
+   */
+  _onTimeout
+
+  /**
+   * The argument to be passed to the callback when the timer expires.
+   *
+   * @type {*}
+   * @private
+   */
+  _timerArg
+
+  /**
+   * @constructor
+   * @param {Function} callback A function to be executed after the timer
+   * expires.
+   * @param {number} delay The time, in milliseconds that the timer should wait
+   * before the specified function or code is executed.
+   * @param {*} arg
+   */
+  constructor (callback, delay, arg) {
+    this._onTimeout = callback
+    this._idleTimeout = delay
+    this._timerArg = arg
+
+    this.refresh()
+  }
+
+  /**
+   * Sets the timer's start time to the current time, and reschedules the timer
+   * to call its callback at the previously specified duration adjusted to the
+   * current time.
+   * Using this on a timer that has already called its callback will reactivate
+   * the timer.
+   *
+   * @returns {void}
+   */
+  refresh () {
+    // In the special case that the timer is not in the list of active timers,
+    // add it back to the array to be processed in the next tick by the onTick
+    // function.
+    if (this._state === NOT_IN_LIST) {
+      fastTimers.push(this)
+    }
+
+    // If the timer is the only active timer, refresh the fastNowTimeout for
+    // better resolution.
+    if (!fastNowTimeout || fastTimers.length === 1) {
+      refreshTimeout()
+    }
+
+    // Setting the state to PENDING will cause the timer to be reset in the
+    // next tick by the onTick function.
+    this._state = PENDING
+  }
+
+  /**
+   * The `clear` method cancels the timer, preventing it from executing.
+   *
+   * @returns {void}
+   * @private
+   */
+  clear () {
+    // Set the state to TO_BE_CLEARED to mark the timer for removal in the next
+    // tick by the onTick function.
+    this._state = TO_BE_CLEARED
+
+    // Reset the _idleStart value to -1 to indicate that the timer is no longer
+    // active.
+    this._idleStart = -1
+  }
+}
+
+/**
+ * This module exports a setTimeout and clearTimeout function that can be
+ * used as a drop-in replacement for the native functions.
+ */
+module.exports = {
+  /**
+   * The setTimeout() method sets a timer which executes a function once the
+   * timer expires.
+   * @param {Function} callback A function to be executed after the timer
+   * expires.
+   * @param {number} delay The time, in milliseconds that the timer should
+   * wait before the specified function or code is executed.
+   * @param {*} [arg] An optional argument to be passed to the callback function
+   * when the timer expires.
+   * @returns {NodeJS.Timeout|FastTimer}
+   */
+  setTimeout (callback, delay, arg) {
+    // If the delay is less than or equal to the RESOLUTION_MS value return a
+    // native Node.js Timer instance.
+    return delay <= RESOLUTION_MS
+      ? setTimeout(callback, delay, arg)
+      : new FastTimer(callback, delay, arg)
+  },
+  /**
+   * The clearTimeout method cancels an instantiated Timer previously created
+   * by calling setTimeout.
+   *
+   * @param {NodeJS.Timeout|FastTimer} timeout
+   */
+  clearTimeout (timeout) {
+    // If the timeout is a FastTimer, call its own clear method.
+    if (timeout[kFastTimer]) {
+      /**
+       * @type {FastTimer}
+       */
+      timeout.clear()
+      // Otherwise it is an instance of a native NodeJS.Timeout, so call the
+      // Node.js native clearTimeout function.
+    } else {
+      clearTimeout(timeout)
+    }
+  },
+  /**
+   * The setFastTimeout() method sets a fastTimer which executes a function once
+   * the timer expires.
+   * @param {Function} callback A function to be executed after the timer
+   * expires.
+   * @param {number} delay The time, in milliseconds that the timer should
+   * wait before the specified function or code is executed.
+   * @param {*} [arg] An optional argument to be passed to the callback function
+   * when the timer expires.
+   * @returns {FastTimer}
+   */
+  setFastTimeout (callback, delay, arg) {
+    return new FastTimer(callback, delay, arg)
+  },
+  /**
+   * The clearTimeout method cancels an instantiated FastTimer previously
+   * created by calling setFastTimeout.
+   *
+   * @param {FastTimer} timeout
+   */
+  clearFastTimeout (timeout) {
+    timeout.clear()
+  },
+  /**
+   * The now method returns the value of the internal fast timer clock.
+   *
+   * @returns {number}
+   */
+  now () {
+    return fastNow
+  },
+  /**
+   * Trigger the onTick function to process the fastTimers array.
+   * Exported for testing purposes only.
+   * Marking as deprecated to discourage any use outside of testing.
+   * @deprecated
+   * @param {number} [delay=0] The delay in milliseconds to add to the now value.
+   */
+  tick (delay = 0) {
+    fastNow += delay - RESOLUTION_MS + 1
+    onTick()
+    onTick()
+  },
+  /**
+   * Reset FastTimers.
+   * Exported for testing purposes only.
+   * Marking as deprecated to discourage any use outside of testing.
+   * @deprecated
+   */
+  reset () {
+    fastNow = 0
+    fastTimers.length = 0
+    clearTimeout(fastNowTimeout)
+    fastNowTimeout = null
+  },
+  /**
+   * Exporting for testing purposes only.
+   * Marking as deprecated to discourage any use outside of testing.
+   * @deprecated
+   */
+  kFastTimer
+}