diff --git a/tracker/tracker/src/webworker/StringDictionary.unit.test.ts b/tracker/tracker/src/webworker/StringDictionary.unit.test.ts
new file mode 100644
index 000000000..8bf17e14b
--- /dev/null
+++ b/tracker/tracker/src/webworker/StringDictionary.unit.test.ts
@@ -0,0 +1,33 @@
+import { describe, expect, test, jest, beforeEach, afterEach } from '@jest/globals'
+import StringDictionary from './StringDictionary.js'
+
+describe('StringDictionary', () => {
+  test('key is non-zero', () => {
+    const dict = new StringDictionary()
+
+    const [key, isNew] = dict.getKey('We are Asayer')
+
+    expect(key).not.toBe(0)
+    expect(isNew).toBe(true)
+  })
+
+  test('Different strings have different keys', () => {
+    const dict = new StringDictionary()
+
+    const [key1, isNew1] = dict.getKey('Datadog')
+    const [key2, isNew2] = dict.getKey('PostHog')
+
+    expect(key1).not.toBe(key2)
+    expect(isNew2).toBe(true)
+  })
+
+  test('Similar strings have similar keys', () => {
+    const dict = new StringDictionary()
+
+    const [key1, isNew1] = dict.getKey("What's up?")
+    const [key2, isNew2] = dict.getKey("What's up?")
+
+    expect(key1).toBe(key2)
+    expect(isNew2).toBe(false)
+  })
+})