fix(lib-storage): add e2e test to trigger validation

Author: smilkuri

lib/lib-storage/src/Upload.spec.ts

@@ -825,7 +825,7 @@ describe(Upload.name, () => {
 
       expect(() => {
         (upload as any).__validateUploadPart(invalidPart, MOCK_PART_SIZE);
-      }).toThrow(`The Part size for part number 1, size 5 does not match expected size ${MOCK_PART_SIZE}`);
+      }).toThrow(`The byte size for part number 1, size 5 does not match expected size ${MOCK_PART_SIZE}`);
     });
 
     it("should allow smaller size for last part", () => {

lib/lib-storage/src/Upload.ts

@@ -440,21 +440,21 @@ export class Upload extends EventEmitter {
   private __validateUploadPart(dataPart: RawDataPart): void {
     const actualPartSize = byteLength(dataPart.data) || undefined;
 
-    // Skip validation for single-part uploads (PUT operations)
-    if (dataPart.partNumber === 1 && dataPart.lastPart) {
-      return;
-    }
-
     if (actualPartSize === undefined) {
       throw new Error(
         `A dataPart was generated without a measurable data chunk size for part number ${dataPart.partNumber}`
       );
     }
 
+    // Skip validation for single-part uploads (PUT operations)
+    if (dataPart.partNumber === 1 && dataPart.lastPart) {
+      return;
+    }
+
     // Validate part size (last part may be smaller)
     if (!dataPart.lastPart && actualPartSize !== this.partSize) {
       throw new Error(
-        `The Part size for part number ${dataPart.partNumber}, size ${actualPartSize} does not match expected size ${this.partSize}`
+        `The byte size for part number ${dataPart.partNumber}, size ${actualPartSize} does not match expected size ${this.partSize}`
       );
     }
   }

lib/lib-storage/src/lib-storage.e2e.spec.ts

@@ -139,6 +139,43 @@ describe("@aws-sdk/lib-storage", () => {
             "S3Client AbortMultipartUploadCommand 204",
           ]);
         });
+
+        it("should validate part size constraints", () => {
+          const upload = new Upload({
+            client,
+            params: {
+              Bucket,
+              Key: `validation-test-${Date.now()}`,
+              Body: Buffer.alloc(1024 * 1024 * 10),
+            },
+          });
+
+          const invalidPart = {
+            partNumber: 2,
+            data: Buffer.alloc(1024 * 1024 * 3), // 3MB - too small for non-final part
+            lastPart: false,
+          };
+
+          expect(() => {
+            (upload as any).__validateUploadPart(invalidPart);
+          }).toThrow(/The byte size for part number 2, size \d+ does not match expected size \d+/);
+        });
+
+        it("should validate part count constraints", async () => {
+          const upload = new Upload({
+            client,
+            params: {
+              Bucket,
+              Key: `validation-test-${Date.now()}`,
+              Body: Buffer.alloc(1024 * 1024 * 10),
+            },
+          });
+
+          (upload as any).uploadedParts = [{ PartNumber: 1, ETag: "etag1" }];
+          (upload as any).isMultiPart = true;
+
+          await expect(upload.done()).rejects.toThrow(/Expected \d+ part\(s\) but uploaded \d+ part\(s\)\./);
+        });
       });
     }
   );