Create a MockDataIntegrityProof Class

[aljones15]

Currently we simply mutate a new instance of DataIntegrityProof to produce invalid test data.
This works, but the

data-integrity-test-suite-assertion/vc-generator/helpers.js

Lines 5 to 98 in 6c3ceb5

	export function invalidCreateProof({
	addCreated = true,
	addVm = true,
	addType = true,
	addProofPurpose = true,
	mockPurpose
	}) {
	return async function({
	document,
	purpose,
	proofSet,
	documentLoader
	}) {
	// build proof (currently known as `signature options` in spec)
	let proof;
	if(this.proof) {
	// shallow copy
	proof = {...this.proof};
	} else {
	// create proof JSON-LD document
	proof = {};
	}
	if(addType) {
	// ensure proof type is set
	proof.type = this.type;
	}
	if(addCreated) {
	// set default `now` date if not given in `proof` or `options`
	let date = this.date;
	if(proof.created === undefined && date === undefined) {
	date = new Date();
	}
	// ensure date is in string format
	if(date && (date instanceof Date)) {
	// replace ms block with Z for seconds precision
	date = date.toISOString().replace(/\.\d+Z$/, 'Z');
	}
	// add API overrides
	if(date) {
	proof.created = date;
	}
	}
	if(addVm) {
	proof.verificationMethod = this.verificationMethod;
	}
	proof.cryptosuite = this.cryptosuite;
	// add any extensions to proof (mostly for legacy support)
	proof = await this.updateProof({
	document, proof, purpose, documentLoader
	});
	if(addProofPurpose) {
	if(mockPurpose) {
	proof.proofPurpose = mockPurpose;
	} else {
	// allow purpose to update the proof; the `proof` is in the
	// SECURITY_CONTEXT_URL `@context` -- therefore the `purpose` must
	// ensure any added fields are also represented in that same `@context`
	proof = await purpose.update(
	proof, {document, suite: this, documentLoader});
	}
	}
	// create data to sign
	let verifyData;
	// use custom cryptosuite `createVerifyData` if available
	if(this._cryptosuite.createVerifyData) {
	verifyData = await this._cryptosuite.createVerifyData({
	cryptosuite: this._cryptosuite,
	document, proof, proofSet, documentLoader,
	dataIntegrityProof: this
	});
	} else {
	verifyData = await this.createVerifyData(
	{document, proof, proofSet, documentLoader});
	}
	// use custom `createProofValue` if available
	if(this._cryptosuite.createProofValue) {
	proof.proofValue = await this._cryptosuite.createProofValue({
	cryptosuite: this._cryptosuite,
	verifyData, document, proof, proofSet,
	documentLoader, dataIntegrityProof: this
	});
	} else {
	// default to simple signing of data
	proof = await this.sign(
	{verifyData, document, proof, proofSet, documentLoader});
	}
	return proof;
	};
	}

invalidCreateProof function has a closure that can not be ammended later. This causes issues when chaining generators, for instance if you want an invalid proof lacking both a type and a verificationMethod it would be hard to do that.

so replace the invalidCreateProof with something like this:

export class MockDataIntegrityProof extends DataIntegrityProof {
  constructor({stubs, mocks, ...args}) {
    super({...args});
    this.stubs = stubs;
    this.mocks = mocks;
  }
  createProof(){
    ..contains current invalidCreateProof
  }
}

The advantage here is a single MockDataIntegrityProof can contain multiple mocks and stubs in one go reducing the need for chaining generators. Generators might still be needed for documentLoaders containing invalid contexts that make the mock proof possible.