6 files changed, 139 insertions, 0 deletions
diff --git a/node_modules/exponential-backoff/src/delay/always/always.delay.spec.ts b/node_modules/exponential-backoff/src/delay/always/always.delay.spec.ts
new file mode 100644
index 0000000..8a08cd8
--- /dev/null
+++ b/node_modules/exponential-backoff/src/delay/always/always.delay.spec.ts
@@ -0,0 +1,65 @@
+import { AlwaysDelay } from "./always.delay";
+import { IBackOffOptions, getSanitizedOptions } from "../../options";
+
+describe(AlwaysDelay.name, () => {
+  let options: IBackOffOptions;
+  let delay: AlwaysDelay;
+
+  function initClass() {
+    delay = new AlwaysDelay(options);
+  }
+
+  beforeEach(() => {
+    options = getSanitizedOptions({});
+    initClass();
+    jest.useFakeTimers();
+  });
+
+  it(`when calling #apply, the delay is equal to the starting delay`, async () => {
+    const spy = jest.fn();
+    delay.apply().then(spy);
+    jest.runTimersToTime(options.startingDelay);
+    await Promise.resolve();
+
+    expect(spy).toHaveBeenCalledTimes(1);
+  });
+
+  it(`when the attempt number is 1, when calling #apply,
+  the delay is equal to the starting delay multiplied by the time multiple`, async () => {
+    delay.setAttemptNumber(1);
+
+    const spy = jest.fn();
+    delay.apply().then(spy);
+    jest.runTimersToTime(options.startingDelay * options.timeMultiple);
+    await Promise.resolve();
+
+    expect(spy).toHaveBeenCalledTimes(1);
+  });
+
+  it(`when the attempt number is 2, when calling #apply,
+  the delay is equal to the starting delay multiplied by the time multiple raised by the attempt number`, async () => {
+    const attemptNumber = 2;
+    delay.setAttemptNumber(attemptNumber);
+
+    const spy = jest.fn();
+    delay.apply().then(spy);
+    jest.runTimersToTime(
+      options.startingDelay * Math.pow(options.timeMultiple, attemptNumber)
+    );
+    await Promise.resolve();
+
+    expect(spy).toHaveBeenCalledTimes(1);
+  });
+
+  it(`when the #maxDelay is less than #startingDelay, when calling #apply,
+  the delay is equal to the #maxDelay`, async () => {
+    options.maxDelay = options.startingDelay - 1;
+
+    const spy = jest.fn();
+    delay.apply().then(spy);
+    jest.runTimersToTime(options.maxDelay);
+    await Promise.resolve();
+
+    expect(spy).toHaveBeenCalledTimes(1);
+  });
+});
diff --git a/node_modules/exponential-backoff/src/delay/always/always.delay.ts b/node_modules/exponential-backoff/src/delay/always/always.delay.ts
new file mode 100644
index 0000000..ec86c62
--- /dev/null
+++ b/node_modules/exponential-backoff/src/delay/always/always.delay.ts
@@ -0,0 +1,3 @@
+import { Delay } from "../delay.base";
+
+export class AlwaysDelay extends Delay {}
+\ No newline at end of file
diff --git a/node_modules/exponential-backoff/src/delay/delay.base.ts b/node_modules/exponential-backoff/src/delay/delay.base.ts
new file mode 100644
index 0000000..bed90d6
--- /dev/null
+++ b/node_modules/exponential-backoff/src/delay/delay.base.ts
@@ -0,0 +1,34 @@
+import { IDelay } from "./delay.interface";
+import { IBackOffOptions } from "../options";
+import { JitterFactory } from "../jitter/jitter.factory";
+
+export abstract class Delay implements IDelay {
+  protected attempt = 0;
+  constructor(private options: IBackOffOptions) {}
+
+  public apply() {
+    return new Promise(resolve => setTimeout(resolve, this.jitteredDelay));
+  }
+
+  public setAttemptNumber(attempt: number) {
+    this.attempt = attempt;
+  }
+
+  private get jitteredDelay() {
+    const jitter = JitterFactory(this.options);
+    return jitter(this.delay);
+  }
+
+  private get delay() {
+    const constant = this.options.startingDelay;
+    const base = this.options.timeMultiple;
+    const power = this.numOfDelayedAttempts;
+    const delay = constant * Math.pow(base, power);
+
+    return Math.min(delay, this.options.maxDelay);
+  }
+
+  protected get numOfDelayedAttempts() {
+    return this.attempt;
+  }
+}
diff --git a/node_modules/exponential-backoff/src/delay/delay.factory.ts b/node_modules/exponential-backoff/src/delay/delay.factory.ts
new file mode 100644
index 0000000..95e89fb
--- /dev/null
+++ b/node_modules/exponential-backoff/src/delay/delay.factory.ts
@@ -0,0 +1,18 @@
+import { IBackOffOptions } from "../options";
+import { SkipFirstDelay } from "./skip-first/skip-first.delay";
+import { AlwaysDelay } from "./always/always.delay";
+import { IDelay } from "./delay.interface";
+
+export function DelayFactory(options: IBackOffOptions, attempt: number): IDelay {
+    const delay = initDelayClass(options);
+    delay.setAttemptNumber(attempt);
+    return delay;
+}
+
+function initDelayClass(options: IBackOffOptions) {
+    if (!options.delayFirstAttempt) {
+        return new SkipFirstDelay(options);
+    }
+
+    return new AlwaysDelay(options);
+}
+\ No newline at end of file
diff --git a/node_modules/exponential-backoff/src/delay/delay.interface.ts b/node_modules/exponential-backoff/src/delay/delay.interface.ts
new file mode 100644
index 0000000..6ecc8da
--- /dev/null
+++ b/node_modules/exponential-backoff/src/delay/delay.interface.ts
@@ -0,0 +1,4 @@
+export interface IDelay {
+  apply: () => Promise<unknown>;
+  setAttemptNumber: (attempt: number) => void;
+}
diff --git a/node_modules/exponential-backoff/src/delay/skip-first/skip-first.delay.ts b/node_modules/exponential-backoff/src/delay/skip-first/skip-first.delay.ts
new file mode 100644
index 0000000..9f2b7f5
--- /dev/null
+++ b/node_modules/exponential-backoff/src/delay/skip-first/skip-first.delay.ts
@@ -0,0 +1,15 @@
+import { Delay } from "../delay.base";
+
+export class SkipFirstDelay extends Delay {
+    public async apply() {
+        return this.isFirstAttempt ? true : super.apply();
+    }
+
+    private get isFirstAttempt() {
+        return this.attempt === 0;
+    }
+
+    protected get numOfDelayedAttempts() {
+        return this.attempt - 1;
+    }
+}
+\ No newline at end of file