Most of the tests that currently cover core functionalities depend heavily on (and sometimes test) internal implementation characteristics. While they should be testing whether the given implementation produces desired outcome (treating its implementation more as a black box).

Current state of things is problematic for eventual internal improvements and refactors which occasionally we want to introduce, as in most of such cases proposed improvements need to be accompanied with counterproductive numerous updates to tests which are covering otherwise not altered functionalities .

At some point, we've introduced a new (black box based) way of testing the internals. It's through runServerless utility, which allows us to create a natural (as in real-world) serverless instance, and inspect the produced outcome for chosen command. More details here: https://github.com/serverless/serverless/tree/master/test#unit-tests

This is issue is about refactoring test/unit/lib/plugins/aws/package/compile/events/stream.test.js to runServerless based variant.

It's needed, so we cleanly move forward with #8396

To make refactor relatively easy:

• Spec for new tests is fully defined and is already committed in. It's in the scope of this describe block:

  serverless/test/unit/lib/plugins/aws/package/compile/events/stream.test.js

  Lines 1446 to 1914 in 654c507

  	describe('test/unit/lib/plugins/aws/package/compile/events/stream.test.js', () => {
  	describe('regular', () => {
  	let eventSourceMappingResource;
  	before(async () => {
  	const { awsNaming, cfTemplate } = await runServerless({
  	fixture: 'function',
  	configExt: {
  	functions: {
  	basic: {
  	events: [
  	{
  	stream: {
  	arn: 'arn:aws:kinesis:us-east-1:123456789012:stream/some-long-name',
  	functionResponseType: 'ReportBatchItemFailures',
  	tumblingWindowInSeconds: 30,
  	filterPatterns: [{ eventName: ['INSERT'] }, { eventName: ['MODIFY'] }],
  	parallelizationFactor: 10,
  	bisectBatchOnFunctionError: true,
  	consumer: true,
  	},
  	},
  	],
  	},
  	dynamo: {
  	handler: 'basic.handler',
  	events: [
  	{
  	stream: {
  	arn: 'arn:aws:dynamodb:region:account:table/foo/stream/1',
  	batchSize: 1,
  	startingPosition: 'LATEST',
  	enabled: false,
  	batchWindow: 15,
  	maximumRetryAttempts: 4,
  	maximumRecordAgeInSeconds: 120,
  	destinations: {
  	onFailure: 'arn:aws:sns:region:account:snstopic',
  	},
  	},
  	},
  	],
  	},
  	kinesisImportCustomIam: {
  	handler: 'basic.handler',
  	role: {
  	'Fn::Sub': 'arn:aws:iam::${AWS::AccountId}:role/iam-role-name',
  	},
  	events: [
  	{
  	stream: {
  	arn: { 'Fn::ImportValue': 'ForeignKinesis' },
  	type: 'kinesis',
  	consumer:
  	'arn:aws:kinesis:region:account:stream/xyz/consumer/foobar:1558544531',
  	},
  	},
  	],
  	},
  	arnVariants: {
  	handler: 'basic.handler',
  	events: [
  	{
  	stream: {
  	arn: { 'Fn::GetAtt': ['SomeDdbTable', 'StreamArn'] },
  	type: 'dynamodb',
  	destinations: {
  	onFailure: {
  	arn: { 'Fn::ImportValue': 'ForeignSQS' },
  	type: 'sqs',
  	},
  	},
  	},
  	},
  	{
  	stream: {
  	arn: {
  	'Fn::Join': [
  	':',
  	[
  	'arn',
  	'aws',
  	'kinesis',
  	{
  	Ref: 'AWS::Region',
  	},
  	{
  	Ref: 'AWS::AccountId',
  	},
  	'stream/MyStream',
  	],
  	],
  	},
  	type: 'kinesis',
  	},
  	},
  	{
  	stream: {
  	arn: { Ref: 'SomeDdbTableStreamArn' },
  	type: 'dynamodb',
  	destinations: {
  	onFailure: {
  	arn: { 'Fn::ImportValue': 'ForeignSQS' },
  	type: 'sqs',
  	},
  	},
  	},
  	},
  	{
  	stream: {
  	arn: { Ref: 'ForeignKinesisStreamArn' },
  	type: 'kinesis',
  	},
  	},
  	],
  	},
  	destinationVariants: {
  	handler: 'basic.handler',
  	events: [
  	{
  	stream: {
  	arn: 'arn:aws:dynamodb:region:account:table/foo/stream/1',
  	destinations: {
  	onFailure: {
  	arn: { 'Fn::GetAtt': ['SomeSNS', 'Arn'] },
  	type: 'sns',
  	},
  	},
  	},
  	},
  	{
  	stream: {
  	arn: 'arn:aws:dynamodb:region:account:table/foo/stream/1',
  	destinations: {
  	onFailure: {
  	arn: {
  	'Fn::Join': [
  	':',
  	[
  	'arn',
  	'aws',
  	'sqs',
  	{
  	Ref: 'AWS::Region',
  	},
  	{
  	Ref: 'AWS::AccountId',
  	},
  	'MyQueue',
  	],
  	],
  	},
  	type: 'sqs',
  	},
  	},
  	},
  	},
  	{
  	stream: {
  	arn: 'arn:aws:dynamodb:region:account:table/buzz/stream/1',
  	destinations: {
  	onFailure: {
  	arn: { Ref: 'SomeSNSArn' },
  	type: 'sns',
  	},
  	},
  	},
  	},
  	{
  	stream: {
  	arn: 'arn:aws:dynamodb:region:account:table/fizz/stream/1',
  	destinations: {
  	onFailure: {
  	arn: { Ref: 'ForeignSQSArn' },
  	type: 'sqs',
  	},
  	},
  	},
  	},
  	],
  	},
  	},
  	},
  	command: 'package',
  	});
  	const streamLogicalId = awsNaming.getStreamLogicalId('basic', 'kinesis', 'some-long-name');
  	eventSourceMappingResource = cfTemplate.Resources[streamLogicalId];
  	});
  	it.skip('TODO: should support ARN String for `arn`', () => {
  	// Replaces
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1106-L1453 (partially)
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1574-L1591
  	//
  	// Confirm effect of:
  	// - `functions.basic.events[0].stream.arn`
  	// - `functions.dynamodb.events[0].stream.arn`
  	});
  	it.skip('TODO: should support Fn::GetAtt for `arn`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L586-L741
  	//
  	// Confirm effect of `functions.arnVariants.events[0].stream.arn`
  	});
  	it.skip('TODO: should support Fn::ImportValue for `arn`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L586-L741
  	//
  	// Confirm effect of `functions.kinesisImportCustomIam.events[0].stream.arn`
  	});
  	it.skip('TODO: should support Fn::Join for `arn`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L586-L741
  	//
  	// Confirm effect of `functions.arnVariants.events[1].stream.arn`
  	});
  	it.skip('TODO: should support Ref for `arn`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L586-L741
  	//
  	// Confirm effect of:
  	// - `functions.arnVariants.events[2].stream.arn`
  	// - `functions.arnVariants.events[3].stream.arn`
  	});
  	it.skip('TODO: should support `batchSize`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L370-L584
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1106-L1453
  	//
  	// Confirm effect of `functions.dynamo.events[0].stream.batchSize`
  	});
  	it.skip('TODO: should support `startingPosition`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L370-L584
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1106-L1453
  	//
  	// Confirm effect of `functions.dynamo.events[0].stream.startingPosition`
  	});
  	it.skip('TODO: should support `enabled`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L370-L584
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1106-L1453
  	//
  	// Confirm effect of `functions.dynamo.events[0].stream.enabled`
  	});
  	it.skip('TODO: should support `batchWindow`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L370-L584
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1106-L1453
  	//
  	// Confirm effect of `functions.dynamo.events[0].stream.batchWindow`
  	});
  	it.skip('TODO: should support `maximumRetryAttempts`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L370-L584
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1106-L1453
  	//
  	// Confirm effect of `functions.dynamo.events[0].stream.maximumRetryAttempts`
  	});
  	it.skip('TODO: should support `maximumRecordAgeInSeconds`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L370-L584
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1106-L1453
  	//
  	// Confirm effect of `functions.dynamo.events[0].stream.maximumRecordAgeInSeconds`
  	});
  	it.skip('TODO: should support `parallelizationFactor`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1106-L1453
  	//
  	// Confirm effect of `functions.basic.events[0].stream.parallelizationFactor`
  	});
  	it.skip('TODO: should support `bisectBatchOnFunctionError`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1106-L1453
  	//
  	// Confirm effect of `functions.basic.events[0].stream.bisectBatchOnFunctionError`
  	});
  	it.skip('TODO: should support `consumer`', () => {
  	// Replaces
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1437-L1465
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1467-L1539 (partially)
  	//
  	// Confirm effect of:
  	// - `functions.basic.events[0].stream.consumer`
  	// - `functions.kinesisImportCustomIam.events[0].stream.consumer`
  	});
  	it.skip('TODO: should support ARN string for `destinations.onFailure`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L370-L584
  	//
  	// Confirm effect of: `functions.dynamo.events[0].stream.destinations`
  	});
  	it.skip('TODO: should support Fn::GetAtt for `destinations.onFailure`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L743-L916
  	//
  	// Confirm effect of: `functions.destinationVariants.events[0].stream.destinations`
  	});
  	it.skip('TODO: should support Fn::ImportValue for `destinations.onFailure`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L743-L916
  	//
  	// Confirm effect of: `functions.arnVariants.events[2].stream.destinations`
  	});
  	it.skip('TODO: should support Fn::Join for `destinations.onFailure`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L743-L916
  	//
  	// Confirm effect of: `functions.destinationVariants.events[1].stream.destinations`
  	});
  	it.skip('TODO: should support Ref for `destinations.onFailure`', () => {
  	// Replaces partially
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L743-L916
  	//
  	// Confirm effect of:
  	// - `functions.destinationVariants.events[2].stream.destinations`
  	// - `functions.destinationVariants.events[3].stream.destinations`
  	});
  	it('should support `functionResponseType`', () => {
  	expect(eventSourceMappingResource.Properties.FunctionResponseTypes).to.include.members([
  	'ReportBatchItemFailures',
  	]);
  	});
  	it('should support `tumblingWindowInSeconds`', () => {
  	expect(eventSourceMappingResource.Properties.TumblingWindowInSeconds).to.equal(30);
  	});
  	it('should support `filterPatterns`', () => {
  	expect(eventSourceMappingResource.Properties.FilterCriteria).to.deep.equal({
  	Filters: [
  	{
  	Pattern: JSON.stringify({ eventName: ['INSERT'] }),
  	},
  	{
  	Pattern: JSON.stringify({ eventName: ['MODIFY'] }),
  	},
  	],
  	});
  	});
  	it.skip('TODO: should ensure necessary IAM statememnts', () => {
  	// Replaces
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L87-L366
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1056-L1103
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L1467-L1539 (partially)
  	//
  	// Confirm expected IAM statements on final role
  	});
  	});
  	describe.skip('TODO: failures', () => {
  	it("should fail if stream `type` is not set and couldn't be assumed", async () => {
  	// Replaces
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L918-L932
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L955-L969
  	await expect(
  	runServerless({
  	fixture: 'function',
  	command: 'package',
  	configExt: {
  	functions: {
  	basic: {
  	events: [
  	{
  	stream: {
  	arn: { Ref: 'SomeDdbTableStreamArn' },
  	},
  	},
  	],
  	},
  	},
  	},
  	})
  	).to.be.eventually.rejected.and.have.property('code', 'TODO');
  	});
  	it("should fail if destination `type` is not set and couldn't be assumed", async () => {
  	// Replaces
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L934-L953
  	// https://github.com/serverless/serverless/blob/f64f7c68abb1d6837ecaa6173f4b605cf3975acf/test/unit/lib/plugins/aws/package/compile/events/stream.test.js#L971-L990
  	await expect(
  	runServerless({
  	fixture: 'function',
  	command: 'package',
  	configExt: {
  	functions: {
  	basic: {
  	events: [
  	{
  	stream: {
  	arn: 'arn:aws:dynamodb:region:account:table/fizz/stream/1',
  	destinations: {
  	onFailure: {
  	arn: { Ref: 'ForeignSQSArn' },
  	},
  	},
  	},
  	},
  	],
  	},
  	},
  	},
  	})
  	).to.be.eventually.rejected.and.have.property('code', 'TODO');
  	});
  	});
  	describe('with provisioned concurrency', () => {
  	let naming;
  	let eventSourceMappingResource;
  	before(async () => {
  	const { awsNaming, cfTemplate } = await runServerless({
  	fixture: 'function',
  	configExt: {
  	functions: {
  	basic: {
  	provisionedConcurrency: 1,
  	events: [{ stream: 'arn:aws:kinesis:us-east-1:123456789012:stream/myStream' }],
  	},
  	},
  	},
  	command: 'package',
  	});
  	naming = awsNaming;
  	const streamLogicalId = awsNaming.getStreamLogicalId('basic', 'kinesis', 'myStream');
  	eventSourceMappingResource = cfTemplate.Resources[streamLogicalId];
  	});
  	it('should reference provisioned alias', () => {
  	expect(eventSourceMappingResource.Properties.FunctionName).to.deep.equal({
  	'Fn::Join': [
  	':',
  	[
  	{
  	'Fn::GetAtt': ['BasicLambdaFunction', 'Arn'],
  	},
  	'provisioned',
  	],
  	],
  	});
  	});
  	it('should depend on provisioned alias', () => {
  	const aliasLogicalId = naming.getLambdaProvisionedConcurrencyAliasLogicalId('basic');
  	expect(eventSourceMappingResource.DependsOn).to.include(aliasLogicalId);
  	});
  	});

• Each test slot indicates which test it is about to replace
• It is indicated where (and how many) exactly runServerless runs are expected to happen, against which fixture and command they should be based
• Necessary hints are provided

For every refactored test, the old test should be removed

Refactor can be submitted with one PR, but partial refactors are also very welcome