Simplified the shouldCompress check and added base64encoded checks

Author: sdangol

packages/event-handler/src/rest/middleware/compress.ts

@@ -104,17 +104,14 @@ const shouldCompress = (
     (acceptedEncoding.includes(preferredEncoding) ||
       acceptedEncoding.includes(COMPRESSION_ENCODING_TYPES.ANY));
 
-  if (
-    !shouldEncode ||
-    isEncodedOrChunked ||
-    request.method === 'HEAD' ||
-    (contentLength && Number(contentLength) < threshold) ||
-    (cacheControl && CACHE_CONTROL_NO_TRANSFORM_REGEX.test(cacheControl)) ||
-    !response.body
-  ) {
-    return false;
-  }
-  return true;
+  return (
+    shouldEncode &&
+    !isEncodedOrChunked &&
+    request.method !== 'HEAD' &&
+    (!contentLength || Number(contentLength) > threshold) &&
+    (!cacheControl || !CACHE_CONTROL_NO_TRANSFORM_REGEX.test(cacheControl)) &&
+    response.body !== null
+  );
 };
 
 export { compress };

packages/event-handler/tests/unit/rest/middleware/compress.test.ts

@@ -32,6 +32,7 @@ describe('Compress Middleware', () => {
     // Assess
     expect(result.headers?.['content-encoding']).toBe('gzip');
     expect(result.headers?.['content-length']).toBeUndefined();
+    expect(result.isBase64Encoded).toBe(true);
     expect(result.body).toEqual(
       gzipSync(JSON.stringify(body)).toString('base64')
     );
@@ -58,6 +59,7 @@ describe('Compress Middleware', () => {
 
     // Assess
     expect(result.headers?.['content-encoding']).toBeUndefined();
+    expect(result.isBase64Encoded).toBe(false);
   });
 
   it('skips compression for HEAD requests', async () => {
@@ -72,6 +74,7 @@ describe('Compress Middleware', () => {
 
     // Assess
     expect(result.headers?.['content-encoding']).toBeUndefined();
+    expect(result.isBase64Encoded).toBe(false);
   });
 
   it('skips compression when already encoded', async () => {
@@ -100,6 +103,7 @@ describe('Compress Middleware', () => {
 
     // Assess
     expect(result.headers?.['content-encoding']).toEqual('gzip');
+    expect(result.isBase64Encoded).toBe(true);
   });
 
   it('skips compression when cache-control no-transform is set', async () => {
@@ -124,6 +128,7 @@ describe('Compress Middleware', () => {
 
     // Assess
     expect(result.headers?.['content-encoding']).toBeUndefined();
+    expect(result.isBase64Encoded).toBe(false);
   });
 
   it('uses specified encoding when provided', async () => {
@@ -149,21 +154,23 @@ describe('Compress Middleware', () => {
 
     // Assess
     expect(result.headers?.['content-encoding']).toBe('deflate');
+    expect(result.isBase64Encoded).toBe(true);
   });
 
   it('does not compress if Accept-Encoding is set to identity', async () => {
     // Prepare
-    const deflateCompressionEvent = createTestEvent('/test', 'GET', {
+    const noCompressionEvent = createTestEvent('/test', 'GET', {
       'Accept-Encoding': 'identity',
     });
     app.get('/test', async () => {
       return body;
     });
 
     // Act
-    const result = await app.resolve(deflateCompressionEvent, context);
+    const result = await app.resolve(noCompressionEvent, context);
 
     // Assess
-    expect(result.headers?.['content-encoding']).not.toBeDefined;
+    expect(result.headers?.['content-encoding']).toBeUndefined();
+    expect(result.isBase64Encoded).toBe(false);
   });
 });