expect transformCredentialInput to move top-level props of W3C credentials inside vc

Based on my reading of the W3C spec, it seems as though top-level optional props like evidence and credentialSubject should be copied inside the vc claim in the resulting JWT encoded credential.

However, when you pass transformCredentialInput an arg of type CredentialPayload they are copied to the top level of the JWT:

const cred = {
  '@context': ['https://www.w3.org/2018/credentials/v1'],
  credentialSubject: {
    id: 'did:ethr:0x435df3eda57154cf8cf7926079881f2912f54db4',
    bar: 'baz',
  },
  evidence: { foo: 'bar' },
  type: ['VerifiableCredential'],
};

transformCredentialInput(cred);

Results in

{
  vc: {
    credentialSubject: { bar: 'baz' },
    '@context': [ 'https://www.w3.org/2018/credentials/v1' ],
    type: [ 'VerifiableCredential' ]
  },
  evidence: { foo: 'bar' },
  sub: 'did:ethr:0x435df3eda57154cf8cf7926079881f2912f54db4'
}

Expect

{
  vc: {
    credentialSubject: { bar: 'baz' },
    '@context': [ 'https://www.w3.org/2018/credentials/v1' ],
    type: [ 'VerifiableCredential' ],
    evidence: { foo: 'bar' }
  },
  sub: 'did:ethr:0x435df3eda57154cf8cf7926079881f2912f54db4'
}

A workaround is to move the props inside a manually constructed vc object. But then it’s unclear whether all of the props should be manually transformed to match the JwtCredentialPayload type or left for the transformation function to handle.

[mirceanis]

yes, and the same for the presentation transforms.

Also it loosely relates to #64 since it relates to JWT-JSON payload conversion.

[joshbax189]

Also, normalizeCredential has the inverse problem:

normalizeCredential({
      vc: {
          credentialSubject: { bar: 'baz' },
          '@context': [ 'https://www w3 org/2018/credentials/v1' ],
          type: [ 'VerifiableCredential' ],
          evidence: { foo: 'bar' }
        },
      sub: 'did:ethr:0x435df3eda57154cf8cf7926079881f2912f54db4'
    })

Result

{
  proof: {},
  vc: { evidence: { foo: 'bar' } },
  credentialSubject: {
    bar: 'baz',
    id: 'did:ethr:0x435df3eda57154cf8cf7926079881f2912f54db4'
  },
  issuer: {},
  type: [ 'VerifiableCredential' ],
  '@context': [ 'https://www.w3.org/2018/credentials/v1' ]
}