From 1d12a96b4dc3ca77e6d9f2ffce49f19fc43d350f Mon Sep 17 00:00:00 2001
From: Jack Ellis <jack.m.ellis@hotmail.co.uk>
Date: Mon, 7 Oct 2024 14:55:16 +0100
Subject: [PATCH] feat: defer

---
 src/__tests__/defer.test.ts | 75 +++++++++++++++++++++++++++++++++++++
 src/defer.ts                |  5 +++
 src/makeJpex.ts             |  2 +
 src/types/JpexInstance.ts   |  3 ++
 yarn.lock                   |  6 +--
 5 files changed, 88 insertions(+), 3 deletions(-)
 create mode 100644 src/__tests__/defer.test.ts
 create mode 100644 src/defer.ts

diff --git a/src/__tests__/defer.test.ts b/src/__tests__/defer.test.ts
new file mode 100644
index 0000000..16580ef
--- /dev/null
+++ b/src/__tests__/defer.test.ts
@@ -0,0 +1,75 @@
+import _jpex, { Jpex } from '..';
+
+let jpex: Jpex;
+type Foo = (v: string) => string;
+type FooAsync = (v: string) => Promise<string>;
+type Bar = string;
+
+beforeEach(() => {
+  jpex = _jpex.extend();
+
+  jpex.factory<Foo>((bar: Bar) => (v: string) => `${v}foo${bar}`);
+  jpex.factory<Bar>(() => 'bar');
+  jpex.factory<FooAsync>((foo: Foo) => async (v: string) => `${foo(v)}async`);
+});
+
+it('returns a function', () => {
+  const foo = jpex.defer<Foo>();
+
+  expect(foo).toBeInstanceOf(Function);
+});
+
+it('does not resolve any dependencies at creation time', () => {
+  jpex.defer<Foo>();
+
+  expect(jpex.$$factories[jpex.infer<Foo>()]?.resolved).toBeFalsy();
+  expect(jpex.$$resolved[jpex.infer<Foo>()]).toBeFalsy();
+  expect(jpex.$$factories[jpex.infer<Bar>()]?.resolved).toBeFalsy();
+  expect(jpex.$$resolved[jpex.infer<Bar>()]).toBeFalsy();
+});
+
+it('resolves and calls the factory at call time', () => {
+  const foo = jpex.defer<Foo>();
+
+  const result = foo('provided');
+
+  expect(result).toBe('providedfoobar');
+});
+
+it('works with async factories', async () => {
+  const foo = jpex.defer<FooAsync>();
+
+  const result = await foo('provided');
+
+  expect(result).toBe('providedfoobarasync');
+});
+
+it('caches the inner function', () => {
+  const spyFactory = jest.fn(() => () => 'spy');
+
+  jpex.factory<Foo>(spyFactory);
+
+  const foo = jpex.defer<Foo>();
+
+  expect(spyFactory).not.toHaveBeenCalled();
+
+  foo('provided');
+
+  expect(spyFactory).toHaveBeenCalledTimes(1);
+
+  foo('provided');
+
+  expect(spyFactory).toHaveBeenCalledTimes(1);
+
+  jpex.clearCache();
+
+  foo('provided');
+  expect(spyFactory).toHaveBeenCalledTimes(2);
+});
+
+it('keeps a list of deferred dependencies', () => {
+  jpex.defer<Foo>();
+
+  expect(jpex.$$deps).toContain(jpex.infer<Foo>());
+  expect(jpex.$$deps).toContain(jpex.infer<Bar>());
+});
diff --git a/src/defer.ts b/src/defer.ts
new file mode 100644
index 0000000..85fa57a
--- /dev/null
+++ b/src/defer.ts
@@ -0,0 +1,5 @@
+import { Dependency, JpexInstance } from './types';
+
+export default function defer(this: JpexInstance, name: Dependency) {
+  return this.encase([name], (fn) => fn);
+}
diff --git a/src/makeJpex.ts b/src/makeJpex.ts
index 64e3ca8..68af872 100644
--- a/src/makeJpex.ts
+++ b/src/makeJpex.ts
@@ -3,6 +3,7 @@ import { constant, factory, service, alias, factoryAsync } from './registers';
 import { resolve, getFactory, resolveAsync } from './resolver';
 import encase from './encase';
 import clearCache from './clearCache';
+import defer from './defer';
 
 const defaultConfig = {
   lifecycle: 'container' as const,
@@ -35,6 +36,7 @@ export default function makeJpex(
     resolve,
     resolveAsync,
     encase,
+    defer,
     clearCache,
     extend(config?: SetupConfig): IJpex {
       return makeJpex(config, this);
diff --git a/src/types/JpexInstance.ts b/src/types/JpexInstance.ts
index 6cbbca6..2d6b665 100644
--- a/src/types/JpexInstance.ts
+++ b/src/types/JpexInstance.ts
@@ -205,6 +205,9 @@ export interface JpexInstance {
     fn: F,
   ): ReturnType<F> & { encased: F };
 
+  defer<T extends AnyFunction>(): T;
+  defer<T extends AnyFunction>(name: Dependency): T;
+
   raw(name: Dependency): AnyFunction;
   raw<T>(): AnyFunction<T>;
   raw<T>(name: Dependency): AnyFunction<T>;
diff --git a/yarn.lock b/yarn.lock
index c0ef0cf..9d4e716 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1275,9 +1275,9 @@
     chalk "^4.0.0"
 
 "@jpex-js/babel-plugin@^1.3.0":
-  version "1.8.0"
-  resolved "https://registry.yarnpkg.com/@jpex-js/babel-plugin/-/babel-plugin-1.8.0.tgz#c0318f45762fdccc440e851be04c7e7216e6564b"
-  integrity sha512-B5SGp2PcdCXWgob3eV2YmA205xqG8qxJuYg3ZFiKvFGJCMvjqnrHx8HAG9NH43IFGry3rt3lCZCiito/dEy9jw==
+  version "1.9.0"
+  resolved "https://registry.yarnpkg.com/@jpex-js/babel-plugin/-/babel-plugin-1.9.0.tgz#758fe356db62179465c88f05fc0b5e2df9dbbaac"
+  integrity sha512-q4LIMl/CW5BoReuYfKvNGSxXAmR/bmqM2ekmJlUmG/aFCgEZIYh5FhLYGU4cQ1dcBcIZBB94m2d9+Esu36RBng==
 
 "@marionebl/sander@^0.6.0":
   version "0.6.1"