merging sync message interaction, in existing pact, alters existing interaction content.

Summary

A pact-ruby-ffi user noted an issue with modifications in tried pact file, which was causing errors when trying to upload to a broker with the same, as the contents were modified inadvertently, thus triggering Pact Brokers dangerous modification of contracts block, stopping the user from uploading their pact file

Originally noted in https://github.com/YOU54F/pact-ruby-ffi/issues/6

Reproduction Steps

create an existing pact with single plugin interaction
create a new plugin interaction that only differs by interaction description

expected: 2 interactions are generated, identical bar interaction description

actual: existing interaction is modified at response[0].contents, when merging 2nd interaction

Detail

Merging of the new interaction with an existing pact, results in the first interaction losing some fields, transforming the first interaction from

      "response": [
        {
          "contents": {
            "content": "",
            "contentType": "application/protobuf;message=.area_calculator.AreaResponse",
            "contentTypeHint": "BINARY",
            "encoded": "base64"
          },
          "metadata": {
            "contentType": "application/protobuf;message=.area_calculator.AreaResponse",
            "grpc-message": "Not implemented",
            "grpc-status": "UNIMPLEMENTED"
          }
        }
      ],

"response": [
  {
    "contents": {
      "content": ""
    },
    "metadata": {
      "contentType": "application/protobuf;message=AreaResponse",
      "grpc-message": "Not implemented",
      "grpc-status": "UNIMPLEMENTED"
    }
  }
],

with a diff of

53,56c53
<             "content": "",
<             "contentType": "application/protobuf;message=.area_calculator.AreaResponse",
<             "contentTypeHint": "BINARY",
<             "encoded": "base64"
---
>             "content": ""

Code Reproduction

test case added to pact_ffi suite in commit - https://github.com/YOU54F/pact-reference/commit/3e0b6ec44dab6b8c88844d724d8cfb42d6626d58

// Issue https://github.com/YOU54F/pact-ruby-ffi/issues/6
#[test_log::test]
fn test_protobuf_plugin_contents_merge_with_existing_interaction() {
  let tmp = tempfile::tempdir().unwrap();
  let tmp_dir = CString::new(tmp.path().to_string_lossy().as_bytes().to_vec()).unwrap();
  // 1. create an existing pact with single plugin interaction
  // 2. create a new plugin interaction that only differs by interaction description
  // expected: 2 interactions are generated, identical bar interaction description
  // actual: existing interaction is modified at response[0].contents, when merging 2nd interaction

  let consumer_name = CString::new("PluginMergeConsumer").unwrap();
  let provider_name = CString::new("PluginMergeProvider").unwrap();
  let contents = json!({
    "pact:proto": fixture_path("proto/area_calculator.proto").to_string_lossy().to_string(),
    "pact:proto-service": "Calculator/calculateOne",
    "pact:content-type": "application/protobuf",
    "request": {
      "rectangle": {
        "length": "matching(number, 3)",
        "width": "matching(number, 3)"
      }
    },
    "responseMetadata": {
      "grpc-status": "UNIMPLEMENTED",
      "grpc-message": "Not implemented"
    }
  });
  let expected_response_contents = json!({
    "content": "",
    "contentType": "application/protobuf;message=.area_calculator.AreaResponse",
    "contentTypeHint": "BINARY",
    "encoded": "base64"
  });
  let plugin_name = CString::new("protobuf").unwrap();
  let contents_str = CString::new(contents.to_string()).unwrap();
  let desc1 = CString::new("description 1").unwrap();
  let desc2 = CString::new("description 2").unwrap();
  let content_type = CString::new("application/grpc").unwrap();
  let address = CString::new("127.0.0.1").unwrap();
  let transport = CString::new("grpc").unwrap();

  // Setup New interaction and write to new pact file - validate .interactions[0].response[0].contents
  let pact_handle: PactHandle = pactffi_new_pact(consumer_name.as_ptr(), provider_name.as_ptr());
  pactffi_with_specification(pact_handle, PactSpecification::V4);
  let i_handle1 = pactffi_new_sync_message_interaction(pact_handle, desc1.as_ptr());
  pactffi_using_plugin(pact_handle, plugin_name.as_ptr(), std::ptr::null());
  pactffi_interaction_contents(i_handle1, InteractionPart::Request, content_type.as_ptr(), contents_str.as_ptr());

  let mock_server_port = pactffi_create_mock_server_for_transport(pact_handle, address.as_ptr(), 0, transport.as_ptr(), null());
  print!("Mock server running on {}", mock_server_port);
  let result_1 = pactffi_pact_handle_write_file(pact_handle, tmp_dir.as_ptr(), false);
  expect!(result_1).to(be_equal_to(0));
  let pact_file: Option<String> = pact_default_file_name(&pact_handle);
  let pact_path = tmp.path().join(pact_file.unwrap());
  pactffi_free_pact_handle(pact_handle);
  let f= File::open(pact_path).unwrap();
  let json: Value = serde_json::from_reader(f).unwrap();
  let interaction_1_response_contents = &json["interactions"][0]["response"][0]["contents"];
  pactffi_cleanup_mock_server(mock_server_port);
  pactffi_cleanup_plugins(pact_handle);
  assert_eq!(
    &expected_response_contents,
    interaction_1_response_contents
  );

  // Setup New interaction and write to existing pact file - validate .interactions[0].response[0].contents
  let pact_handle_2: PactHandle = pactffi_new_pact(consumer_name.as_ptr(), provider_name.as_ptr());
  pactffi_with_specification(pact_handle_2, PactSpecification::V4);
  let i_handle2 = pactffi_new_sync_message_interaction(pact_handle_2, desc2.as_ptr());
  pactffi_using_plugin(pact_handle_2, plugin_name.as_ptr(), std::ptr::null());
  pactffi_interaction_contents(i_handle2, InteractionPart::Request, content_type.as_ptr(), contents_str.as_ptr());
  let mock_server_port_2 = pactffi_create_mock_server_for_transport(pact_handle_2, address.as_ptr(), 0, transport.as_ptr(), null());
  print!("Mock server running on {}", mock_server_port_2);
  let result_2 = pactffi_pact_handle_write_file(pact_handle_2, tmp_dir.as_ptr(), false);
  expect!(result_2).to(be_equal_to(0));
  let pact_file_2: Option<String> = pact_default_file_name(&pact_handle_2);
  let pact_path_2 = tmp.path().join(pact_file_2.unwrap());
  pactffi_free_pact_handle(pact_handle_2);
  let f_2= File::open(pact_path_2).unwrap();
  let json_2: Value = serde_json::from_reader(f_2).unwrap();
  let interaction_2_description = &json_2["interactions"][0]["description"];
  let interaction_2_description_2 = &json_2["interactions"][1]["description"];
  let interaction_2_response_contents = &json_2["interactions"][0]["response"][0]["contents"];
  let interaction_2_response_contents_2 = &json_2["interactions"][1]["response"][0]["contents"];
  pactffi_cleanup_mock_server(mock_server_port_2);
  pactffi_cleanup_plugins(pact_handle_2);
  assert_eq!("description 1", interaction_2_description.as_str().unwrap());
  assert_eq!("description 2", interaction_2_description_2.as_str().unwrap());
  assert_eq!(
    &expected_response_contents,
    interaction_2_response_contents_2
  );
  assert_eq!(
    &expected_response_contents,
    interaction_2_response_contents
  );

}

Test Output

thread 'test_protobuf_plugin_contents_merge_with_existing_interaction' panicked at pact_ffi/tests/tests.rs:1941:3:
assertion failed: `(left == right)`

Diff < left / right > :
 Object {
     "content": String(""),
<    "contentType": String("application/protobuf;message=.area_calculator.AreaResponse"),
<    "contentTypeHint": String("BINARY"),
<    "encoded": String("base64"),
 }

note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Mock server running on 58219Mock server running on 58226test test_protobuf_plugin_contents_merge_with_existing_interaction ... FAILED

failures:

failures:
    test_protobuf_plugin_contents_merge_with_existing_interaction

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 36 filtered out; finished in 0.68s

error: test failed, to rerun pass `--test tests`

Relevant logs

Issue occurs when invoking the write pact function. Somewhere in these function calls

pact_models::pact: Merging pact with file "PluginMergeConsumer-PluginMergeProvider.json"
pact_models::file_utils: Attempt 0 of 3 to get a shared lock on '"PluginMergeConsumer-PluginMergeProvider.json"'
pact_models::file_utils: Got shared file lock
pact_models::file_utils: Releasing shared file lock
pact_models::pact: load_pact_from_json: found spec version V4 in metadata
pact_models::v4::pact: from_json: Loading a V4 pact from JSON
pact_models::matchingrules: rule_type: number, attributes: {"match":"number"}
pact_models::matchingrules: rule_type: number, attributes: {"match":"number"}
pact_models::file_utils: Attempt 0 of 3 to get an exclusive lock on '"PluginMergeConsumer-PluginMergeProvider.json"'
pact_models::file_utils: Got exclusive file lock
pact_models::file_utils: Releasing exclusive file lock

pact-foundation / pact-reference