diff --git a/packages/ses/test/error/test-note-log-args.js b/packages/ses/test/error/test-note-log-args.js
index c0f5b19f9e..7de7d680f7 100644
--- a/packages/ses/test/error/test-note-log-args.js
+++ b/packages/ses/test/error/test-note-log-args.js
@@ -2,7 +2,6 @@
 import test from 'ava';
 
 import { makeNoteLogArgsArrayKit } from '../../src/error/note-log-args.js';
-import { makeLRUCacheMap } from '../../src/make-lru-cachemap.js';
 
 test('note log args array kit basic', t => {
   const { addLogArgs, takeLogArgsArray } = makeNoteLogArgsArrayKit(3, 2);
@@ -24,40 +23,3 @@ test('note log args array kit basic', t => {
   t.deepEqual(takeLogArgsArray(e3), undefined);
   t.deepEqual(takeLogArgsArray(e4), [['d']]);
 });
-
-test('weak LRUCacheMap', t => {
-  /** @type {WeakMap<{}, number>} */
-  const lru = makeLRUCacheMap(3);
-  const o1 = {};
-  const o2 = {};
-  const o3 = {};
-  const o4 = {};
-
-  // Overflow drops the oldest.
-  lru.set(o1, 1);
-  t.is(lru.get(o1), 1);
-  lru.set(o3, 2);
-  lru.set(o2, 3);
-  lru.set(o4, 4); // drops o1
-  t.falsy(lru.has(o1));
-  t.is(lru.get(o4), 4);
-  lru.set(o4, 5);
-  t.is(lru.get(o4), 5);
-  t.true(lru.has(o4));
-  lru.set(o1, 6); // drops o3
-  t.is(lru.get(o1), 6);
-  t.false(lru.has(o3));
-
-  // Explicit delete keeps all other elements.
-  lru.delete(o1); // explicit delete o1
-  t.is(lru.get(o1), undefined);
-  t.false(lru.has(o1));
-  t.true(lru.has(o2));
-  t.true(lru.has(o4));
-  t.false(lru.has(o3));
-  lru.set(o3, 7);
-  lru.set(o1, 8); // drops o2
-  t.false(lru.has(o2));
-  t.is(lru.get(o1), 8);
-  t.is(lru.get(o3), 7);
-});
diff --git a/packages/ses/test/test-lru-cache-map.js b/packages/ses/test/test-lru-cache-map.js
index 27599d7cde..4d346ea2dc 100644
--- a/packages/ses/test/test-lru-cache-map.js
+++ b/packages/ses/test/test-lru-cache-map.js
@@ -1,22 +1,78 @@
+// @ts-check
 import test from 'ava';
 
 import { makeLRUCacheMap } from '../src/make-lru-cachemap.js';
 
-test('lru cache map basic', t => {
+test('makeLRUCacheMap', t => {
+  /** @type {WeakMap<{}, number>} */
   const lruMap = makeLRUCacheMap(2);
+  const assertNoEntry = key => {
+    t.is(lruMap.has(key), false);
+    t.is(lruMap.get(key), undefined);
+  };
+  const assertEntry = (key, expectedValue) => {
+    t.is(lruMap.has(key), true);
+    t.is(lruMap.get(key), expectedValue);
+  };
   const key1 = {};
   const key2 = {};
   const key3 = {};
-  t.is(lruMap.has(key1), false);
+  assertNoEntry(key1);
 
+  // Populate up to capacity.
   lruMap.set(key1, 'x');
   lruMap.set(key2, 'y');
-  t.is(lruMap.has(key2), true);
-  t.is(lruMap.has(key1), true);
-  t.is(lruMap.has(key3), false);
+  assertEntry(key2, 'y');
+  assertEntry(key1, 'x');
+  assertNoEntry(key3);
 
+  // Evict key2.
   lruMap.set(key3, 'z');
-  t.is(lruMap.has(key1), true);
-  t.is(lruMap.has(key2), false);
-  t.is(lruMap.has(key3), true);
+  assertEntry(key1, 'x');
+  assertNoEntry(key2);
+  assertEntry(key3, 'z');
+
+  // Overwrite key3.
+  lruMap.set(key3, 'zz');
+  assertEntry(key1, 'x');
+  assertNoEntry(key2);
+  assertEntry(key3, 'zz');
+
+  // Evict key1.
+  lruMap.set(key2, 'y');
+  assertNoEntry(key1);
+  assertEntry(key2, 'y');
+  assertEntry(key3, 'zz');
+
+  // Delete key3, preserving key2.
+  lruMap.delete(key3);
+  assertNoEntry(key1);
+  assertEntry(key2, 'y');
+  assertNoEntry(key3);
+
+  // Add key1, preserving key2.
+  lruMap.set(key1, 'x');
+  assertEntry(key2, 'y');
+  assertEntry(key1, 'x');
+  assertNoEntry(key3);
+
+  // Delete key2, preserving key1.
+  lruMap.delete(key2);
+  assertEntry(key1, 'x');
+  assertNoEntry(key2);
+  assertNoEntry(key3);
+
+  // Delete key1.
+  lruMap.delete(key1);
+  assertNoEntry(key1);
+  assertNoEntry(key2);
+  assertNoEntry(key3);
+
+  // Repopulate with eviction.
+  lruMap.set(key1, 'xx');
+  lruMap.set(key2, 'yy');
+  lruMap.set(key3, 'zz');
+  assertNoEntry(key1);
+  assertEntry(key2, 'yy');
+  assertEntry(key3, 'zz');
 });