fix: set instruction file content length

src/main/java/software/amazon/encryption/s3/internal/InstructionFileConfig.java

@@ -65,10 +65,12 @@ PutObjectResponse putInstructionFile(PutObjectRequest request, String instructio
         instFileMetadata.put(INSTRUCTION_FILE, "");
 
         // Use toBuilder to keep all other fields the same as the actual request
+        // but set the content length, key, and metadata appropriately for the instruction file
         final PutObjectRequest instPutRequest = request.toBuilder()
-          .key(request.key() + instructionFileSuffix)
-          .metadata(instFileMetadata)
-          .build();
+            .key(request.key() + instructionFileSuffix)
+            .contentLength((long) instructionFileContent.getBytes().length)
+            .metadata(instFileMetadata)
+            .build();
         switch (_clientType) {
             case SYNCHRONOUS:
                 return _s3Client.putObject(instPutRequest, RequestBody.fromString(instructionFileContent));

src/test/java/software/amazon/encryption/s3/internal/InstructionFileConfigUploadTest.java

@@ -0,0 +1,73 @@
+package software.amazon.encryption.s3.internal;
+
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentCaptor;
+import software.amazon.awssdk.core.async.AsyncRequestBody;
+import software.amazon.awssdk.core.sync.RequestBody;
+import software.amazon.awssdk.services.s3.S3AsyncClient;
+import software.amazon.awssdk.services.s3.S3Client;
+import software.amazon.awssdk.services.s3.model.PutObjectRequest;
+
+import java.util.concurrent.CompletableFuture;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.*;
+
+class InstructionFileConfigUploadTest {
+
+    @Test
+    void uploadInstructionFileWithSetContentLengthSyncClient() {
+        // Create a mock for the S3 client
+        S3Client mockedS3Client = mock(S3Client.class);
+        // The argument captor is used to capture the PutObjectRequest passed to the putObject method
+        ArgumentCaptor<PutObjectRequest> instructionFilePutCaptor = ArgumentCaptor.forClass(PutObjectRequest.class);
+
+        // Create the InstructionFileConfig with the mocked S3 client
+        InstructionFileConfig instructionFileConfig = InstructionFileConfig.builder()
+                .instructionFileClient(mockedS3Client)
+                .enableInstructionFilePutObject(true)
+                .build();
+
+        // Build some data for the test
+        PutObjectRequest putObjectRequest = PutObjectRequest.builder()
+                .key("someKey").build();
+        String instructionFileContent = "some content that fakes an instruction file";
+
+        // call the actual method under test
+        instructionFileConfig.putInstructionFile(putObjectRequest, instructionFileContent);
+
+        // Verify that the putObject method was called and the captured request has the correct content length
+        verify(mockedS3Client).putObject(instructionFilePutCaptor.capture(), any(RequestBody.class));
+        assertEquals(instructionFileContent.getBytes().length, instructionFilePutCaptor.getValue().contentLength());
+    }
+
+    @Test
+    void uploadInstructionFileWithSetContentLengthAsyncClient() {
+        // Create a mock for the S3 client
+        S3AsyncClient mockedS3Client = mock(S3AsyncClient.class);
+        // The async putObject method returns a CompletableFuture, so we need to mock that behavior
+        when(mockedS3Client.putObject(any(PutObjectRequest.class), any(AsyncRequestBody.class)))
+                .thenReturn(CompletableFuture.completedFuture(null));
+        // The argument captor is used to capture the PutObjectRequest passed to the putObject method
+        ArgumentCaptor<PutObjectRequest> instructionFilePutCaptor = ArgumentCaptor.forClass(PutObjectRequest.class);
+
+        // Create the InstructionFileConfig with the mocked S3 async client
+        InstructionFileConfig instructionFileConfig = InstructionFileConfig.builder()
+                .instructionFileAsyncClient(mockedS3Client)
+                .enableInstructionFilePutObject(true)
+                .build();
+
+        // Build some data for the test
+        PutObjectRequest putObjectRequest = PutObjectRequest.builder()
+                .key("someKey").build();
+        String instructionFileContent = "some content that fakes an instruction file";
+
+        // call the actual method under test
+        instructionFileConfig.putInstructionFile(putObjectRequest, instructionFileContent);
+
+        // Verify that the putObject method was called and the captured request has the correct content length
+        verify(mockedS3Client).putObject(instructionFilePutCaptor.capture(), any(AsyncRequestBody.class));
+        assertEquals(instructionFileContent.getBytes().length, instructionFilePutCaptor.getValue().contentLength());
+    }
+}