Add ignored_fields to test config

[mtojek]

Issue: elastic/elastic-package#169

This PR adds ignored_fields property definition to the test config.

[elasticmachine]

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• Build Cause: [Pull request #82 updated]

• Start Time: 2020-11-12T10:14:43.729+0000

• Duration: 2 min 3 sec

[ycombinator]

I read through the use case for this PR: elastic/elastic-package#169. My understanding is that there will be some fields in the indexed documents that will have dynamic values - values whose value will be different each time the test is executed. However, these fields' values should still conform to a specific data type and shape.

So I would not recommend that we completely allow certain fields to be ignored. Instead, perhaps we can allow users to specify certain fields in the test config and specify a valid pattern for that field's value. So something like:

Suggested change

	"ignored_fields": [
	"foobar",
	"world",
	"hello"
	]
	"dynamic_fields": {
	"foobar": ".*",
	"a_numeric_field": "\\d+"
	}

I'm not married to the name of this setting; just using dynamic_fields as a suggestion above.

This way we can allow for dynamic values for specific fields without completely ignoring them. WDYT?

[mtojek]

However, these fields' values should still conform to a specific data type and shape.

This is a good argument for dynamic fields.

Instead, perhaps we can allow users to specify certain fields in the test config and specify a valid pattern for that field's value.

We'll need to update the pipeline test runner to make the diff more smarter (consider regular expressions), but I think it's possible.

[ycombinator]

LGTM.