memo test

test/memo.ts

@@ -0,0 +1,69 @@
+import t from 'tap'
+import { LRUCache } from '../src/index.js'
+
+t.throws(
+  () =>
+    new LRUCache<number, number>({
+      max: 1,
+      //@ts-expect-error
+      memoMethod: true,
+    })
+)
+t.throws(() => new LRUCache({ max: 1 }).memo(3))
+
+t.test('no funny business', t => {
+  const memoCalls: number[] = []
+  const c = new LRUCache<number, number>({
+    max: 5,
+    memoMethod: k => {
+      memoCalls.push(k)
+      return k ** k
+    },
+  })
+  t.equal(c.get(2), undefined)
+  const four = c.memo(2)
+  const fur = c.memo(2)
+  t.equal(four, 4)
+  t.equal(fur, 4)
+  t.equal(c.get(2), 4)
+  t.strictSame(memoCalls, [2], 'only called once')
+  t.end()
+})
+
+t.test('with context', t => {
+  const memoCalls: [number, number | undefined, boolean][] = []
+  // if there's a value already, and context is set, assign a shorter TTL
+  const memoMethod = (
+    k: number,
+    v: number | undefined,
+    {
+      context,
+      options,
+    }: LRUCache.MemoizerOptions<number, number, boolean>
+  ) => {
+    memoCalls.push([k, v, context])
+    t.type(context, 'boolean')
+    if (context) {
+      return k
+    } else {
+      t.equal(options.noDeleteOnStaleGet, true)
+      return k ** k
+    }
+  }
+
+  const c = new LRUCache<number, number, boolean>({
+    memoMethod,
+    max: 5,
+  })
+  t.equal(c.memo(1, { context: true }), 1)
+  t.equal(c.memo(1, { context: true }), 1)
+  t.equal(c.memo(1, { context: false }), 1)
+  t.equal(c.memo(2, { context: false, noDeleteOnStaleGet: true }), 4)
+  t.equal(c.memo(2, { context: true }), 4)
+  t.equal(c.memo(2, { context: false }), 4)
+  t.strictSame(memoCalls, [
+    [1, undefined, true],
+    [2, undefined, false],
+  ])
+  t.end()
+})