Implement Configurable File Validation

[atonks2]

Because there are so many ICL specifications, not to mention vendors who deviate from those specs, this project needs to be more flexible in the way it validates files. One potential approach would be to implement a ValidateOpts struct containing flags to tailor the validation behavior.

For examples of how this pattern has been implemented in our other OSS repos, see:

• ACH: https://github.com/moov-io/ach/blob/719968e674cced90ace172b81e7ece9be8bca12c/file.go#L72
• Wire: https://github.com/moov-io/wire/blob/3b5b8d23fea6e4dbff6dd901ae3dd87096b95a64/fedWireMessage.go#L10

[atonks2]

This issue came up in the community Slack group, specifically regarding the ArchiveTypeIndicator field.

Is there a way to solve this or ignore the error and continue parsing? I know 1 is invalid as a ArchiveTypeIndicator, but I am still trying to read the rest of the file.

[atonks2]

Proposed implementation:

• Use the ACH implementation as a template for these changes
• Avoid breaking changes
• Define a ValidateOpts struct to include flags for customizing validation behaviors
  • SkipAll for skipping all validation checks (see ACH for example)
  • SkipArchiveTypeIndicator to skip validation of ArchiveTypeIndicator
• Add a validateOpts field to the ICL File (here)
  • Example from ACH here

[mfdeveloper508]

#295