From fae38f14702e925d1e59051d7e5cb3a9a78bfde8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20Unneb=C3=A4ck?= <linus@folkdatorn.se>
Date: Mon, 4 Jul 2022 22:51:11 +0200
Subject: [PATCH] fix: add typings and test for priming with promise (#252)

* Add typings and test for priming with promise

* add changeset

Co-authored-by: Saihajpreet Singh <saihajpreet.singh@gmail.com>
---
 .changeset/lucky-poets-fail.md   |  5 +++++
 src/__tests__/dataloader.test.js | 16 ++++++++++++++++
 src/index.d.ts                   |  2 +-
 src/index.js                     |  2 +-
 4 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/lucky-poets-fail.md

diff --git a/.changeset/lucky-poets-fail.md b/.changeset/lucky-poets-fail.md
new file mode 100644
index 0000000..ad4715a
--- /dev/null
+++ b/.changeset/lucky-poets-fail.md
@@ -0,0 +1,5 @@
+---
+"dataloader": patch
+---
+
+Fix types for priming cache with promise
diff --git a/src/__tests__/dataloader.test.js b/src/__tests__/dataloader.test.js
index 47b2059..e53483f 100644
--- a/src/__tests__/dataloader.test.js
+++ b/src/__tests__/dataloader.test.js
@@ -380,6 +380,22 @@ describe('Primary API', () => {
     expect(loadCalls).toEqual([ [ 'B' ] ]);
   });
 
+  it('allows priming the cache with a promise', async () => {
+    const [ identityLoader, loadCalls ] = idLoader<string>();
+
+    identityLoader.prime('A', Promise.resolve('A'));
+
+    const [ a, b ] = await Promise.all([
+      identityLoader.load('A'),
+      identityLoader.load('B')
+    ]);
+
+    expect(a).toBe('A');
+    expect(b).toBe('B');
+
+    expect(loadCalls).toEqual([ [ 'B' ] ]);
+  });
+
 });
 
 describe('Represents Errors', () => {
diff --git a/src/index.d.ts b/src/index.d.ts
index ee3c8b6..6709279 100644
--- a/src/index.d.ts
+++ b/src/index.d.ts
@@ -56,7 +56,7 @@ declare class DataLoader<K, V, C = K> {
    * Adds the provided key and value to the cache. If the key already exists, no
    * change is made. Returns itself for method chaining.
    */
-  prime(key: K, value: V | Error): this;
+  prime(key: K, value: V | PromiseLike<V> | Error): this;
 }
 
 declare namespace DataLoader {
diff --git a/src/index.js b/src/index.js
index 85689c8..87dade9 100644
--- a/src/index.js
+++ b/src/index.js
@@ -178,7 +178,7 @@ class DataLoader<K, V, C = K> {
    *
    * To prime the cache with an error at a key, provide an Error instance.
    */
-  prime(key: K, value: V | Error): this {
+  prime(key: K, value: V | Promise<V> | Error): this {
     var cacheMap = this._cacheMap;
     if (cacheMap) {
       var cacheKey = this._cacheKeyFn(key);