Add comprehensive integration tests for download with StorageContentValidationDecoderPolicy

Co-authored-by: gunjansingh-msft <[email protected]>

Author: Copilot

sdk/storage/azure-storage-blob/src/test/java/com/azure/storage/blob/specialized/BlobBaseAsyncApiTests.java

@@ -607,6 +607,96 @@ public void downloadStreamWithResponseContentValidationRange() throws IOExceptio
             }).verifyComplete();
     }
 
+    @Test
+    public void downloadStreamWithResponseContentValidationLargeBlob() throws IOException {
+        // Test with larger data to verify chunking works correctly
+        byte[] randomData = getRandomByteArray(5 * Constants.KB);
+        StructuredMessageEncoder encoder
+            = new StructuredMessageEncoder(randomData.length, 1024, StructuredMessageFlags.STORAGE_CRC64);
+        ByteBuffer encodedData = encoder.encode(ByteBuffer.wrap(randomData));
+
+        Flux<ByteBuffer> input = Flux.just(encodedData);
+
+        DownloadContentValidationOptions validationOptions
+            = new DownloadContentValidationOptions().setStructuredMessageValidationEnabled(true);
+
+        StepVerifier
+            .create(bc.upload(input, null, true)
+                .then(bc.downloadStreamWithResponse(null, null, null, false, validationOptions))
+                .flatMap(r -> FluxUtil.collectBytesInByteBufferStream(r.getValue())))
+            .assertNext(r -> TestUtils.assertArraysEqual(r, randomData))
+            .verifyComplete();
+    }
+
+    @Test
+    public void downloadStreamWithResponseContentValidationMultipleSegments() throws IOException {
+        // Test with multiple segments to ensure all segments are decoded correctly
+        byte[] randomData = getRandomByteArray(2 * Constants.KB);
+        StructuredMessageEncoder encoder
+            = new StructuredMessageEncoder(randomData.length, 512, StructuredMessageFlags.STORAGE_CRC64);
+        ByteBuffer encodedData = encoder.encode(ByteBuffer.wrap(randomData));
+
+        Flux<ByteBuffer> input = Flux.just(encodedData);
+
+        DownloadContentValidationOptions validationOptions
+            = new DownloadContentValidationOptions().setStructuredMessageValidationEnabled(true);
+
+        StepVerifier
+            .create(bc.upload(input, null, true)
+                .then(bc.downloadStreamWithResponse(null, null, null, false, validationOptions))
+                .flatMap(r -> FluxUtil.collectBytesInByteBufferStream(r.getValue())))
+            .assertNext(r -> TestUtils.assertArraysEqual(r, randomData))
+            .verifyComplete();
+    }
+
+    @Test
+    public void downloadStreamWithResponseNoValidation() throws IOException {
+        // Test that download works normally when validation is not enabled
+        byte[] randomData = getRandomByteArray(Constants.KB);
+        StructuredMessageEncoder encoder
+            = new StructuredMessageEncoder(randomData.length, 512, StructuredMessageFlags.STORAGE_CRC64);
+        ByteBuffer encodedData = encoder.encode(ByteBuffer.wrap(randomData));
+
+        Flux<ByteBuffer> input = Flux.just(encodedData);
+
+        // No validation options - should download encoded data as-is
+        StepVerifier
+            .create(bc.upload(input, null, true)
+                .then(bc.downloadStreamWithResponse(null, null, null, false))
+                .flatMap(r -> FluxUtil.collectBytesInByteBufferStream(r.getValue())))
+            .assertNext(r -> {
+                assertNotNull(r);
+                // Should get encoded data, not decoded
+                assertTrue(r.length > randomData.length); // Encoded data is larger
+            })
+            .verifyComplete();
+    }
+
+    @Test
+    public void downloadStreamWithResponseValidationDisabled() throws IOException {
+        // Test with validation options but validation disabled
+        byte[] randomData = getRandomByteArray(Constants.KB);
+        StructuredMessageEncoder encoder
+            = new StructuredMessageEncoder(randomData.length, 512, StructuredMessageFlags.STORAGE_CRC64);
+        ByteBuffer encodedData = encoder.encode(ByteBuffer.wrap(randomData));
+
+        Flux<ByteBuffer> input = Flux.just(encodedData);
+
+        DownloadContentValidationOptions validationOptions
+            = new DownloadContentValidationOptions().setStructuredMessageValidationEnabled(false);
+
+        StepVerifier
+            .create(bc.upload(input, null, true)
+                .then(bc.downloadStreamWithResponse(null, null, null, false, validationOptions))
+                .flatMap(r -> FluxUtil.collectBytesInByteBufferStream(r.getValue())))
+            .assertNext(r -> {
+                assertNotNull(r);
+                // Should get encoded data, not decoded
+                assertTrue(r.length > randomData.length); // Encoded data is larger
+            })
+            .verifyComplete();
+    }
+
     @RequiredServiceVersion(clazz = BlobServiceVersion.class, min = "2024-08-04")
     @Test
     public void copyFromURLSourceErrorAndStatusCode() {