Fix HEAD caching behavior, update tests

src/HTTPCache.ts

@@ -57,6 +57,11 @@ export class HTTPCache {
     requestOpts.method = requestOpts.method ?? 'GET';
     const cacheKey = cache?.cacheKey ?? urlString;
 
+    // Bypass the cache altogether for HEAD requests
+    if (requestOpts.method === 'HEAD') {
+      return this.httpFetch(urlString, requestOpts);
+    }
+
     const entry = await this.keyValueCache.get(cacheKey);
     if (!entry) {
       // There's nothing in our cache. Fetch the URL and save it to the cache if

src/__tests__/HTTPCache.test.ts

@@ -491,21 +491,34 @@ describe('HTTPCache', () => {
   });
 
   describe('HEAD requests', () => {
-    it('returns a cached GET response when the method is HEAD', async () => {
-      mockGetAdaLovelace();
+    it('bypasses the cache', async () => {
+      // x2
+      nock(apiUrl).head(adaPath).times(2).reply(200);
 
-      await httpCache.fetch(adaUrl, {}, { cacheOptions: { ttl: 30000 } });
+      await httpCache.fetch(adaUrl, {
+        method: 'HEAD',
+      });
 
-      const headResponse = await httpCache.fetch(adaUrl, {
+      await httpCache.fetch(adaUrl, {
         method: 'HEAD',
       });
+    });
 
-      expect(headResponse.status).toEqual(200);
-      expect(await headResponse.json()).toMatchInlineSnapshot(`
+    it('bypasses the cache even with explicit ttl', async () => {
+      // x2
+      nock(apiUrl).head(adaPath).times(2).reply(200);
+
+      await httpCache.fetch(
+        adaUrl,
         {
-          "name": "Ada Lovelace",
-        }
-      `);
+          method: 'HEAD',
+        },
+        { cacheOptions: { ttl: 30000 } },
+      );
+
+      await httpCache.fetch(adaUrl, {
+        method: 'HEAD',
+      });
     });
   });
 });