21 referencing a workflow crate mk2

[douglowe]

This is PR #26, but with the commit history cleaned up.

Rules implemented

Description	sh:severity
The RootDataEntity MUST have the schema:mainEntity property with cardinality 1.	sh:Violation
The mainEntity pointed to by the RootDataEntity MUST be of type schema:Dataset.	sh:Violation
The mainEntity MUST have a purl:conformsTo property with an IRI starting with "https://w3id.org/workflowhub/workflow-ro-crate"	sh:Violation
If mainEntity has an HTTP(S) @id, it SHOULD have a distribution that is an HTTP(S) URL.	sh:Warning

---

Rules NOT implemented

There are other rules pertaining to the mainEntity, but these were deemed to be not implementable.
For sake of completeness these are reported below

Description	sh:severity
The @id of the mainEntity SHOULD be a permalink or versioned URL	sh:Warning
The @id of the mainEntity MAY be a nested directory in the payload.	sh:Info
Workflow programming language and detailed metadata MUST be provided in the referenced Workflow RO-Crate, not this crate	sh:Violation
If present in the referenced Workflow RO-Crate, SHOULD be either CWL or Nextflow URIs.	sh:Warning
If the identifier is not a URI, Clients SHOULD follow Signposting headers to find the rel="item" link to the RO-Crate ZIP file	sh:Warning

[douglowe]

I've added back in the files:

rocrate_validator/profiles/five-safes-crate/must/1_root_data_entity.ttl
rocrate_validator/profiles/five-safes-crate/should/1_requesting_agent.ttl

So that all our tests pass.

Do we need these files, and the checks they contain?

If not we should reverse out commit 06303a4, and also remove the tests which rely on these checks.

[elichad]

I've added back in the files:

rocrate_validator/profiles/five-safes-crate/must/1_root_data_entity.ttl
rocrate_validator/profiles/five-safes-crate/should/1_requesting_agent.ttl

So that all our tests pass.

Do we need these files, and the checks they contain?

If not we should reverse out commit 06303a4, and also remove the tests which rely on these checks.

@douglowe We do need these files - they were added in #27 and #13 respectively. In both cases GitHub treated it as a rename of another file, which I think is why they got temporarily dropped when you put this PR together. Thanks for adding them back.

[EttoreM]

@alexhambley 's comments on the superseded PR were addressed and resolved in this PR.

[ianhinder]

@alexhambley will check that the comments from #26 have been addressed in here, and review it.

[alexhambley]

The five-safes-crate::DatasetMustHaveDistributionIfURI in this commit still has two colons

[EttoreM]

The five-safes-crate::DatasetMustHaveDistributionIfURI in this commit still has two colons

Fixed now.

Can we merge now?