Allow empty tunable values to represent the defaults

[bpkroth]

Pull Request

Title

Allows an empty dictionary (object) to represent the default tunable values for tunable params.

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Description

This should make it easier to maintain configs that loop over a chosen set of tunable values, where some of the tunable values are the default values without needing to copy/paste those values from the tunable params definitions.

• See Also: discussion in #855

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Type of Change

• ✨ New feature

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Testing

Extends existing testing infrastructure to check that this works.

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[bpkroth]

As noted in the linked discussion, an alternative could be to allow null to represent the defaults, but this seemed reasonably clean.

Prior to this {} would basically be a no-op (i.e., doesn't change any of the values of the current config), which I guess also makes sense, but is also probably also confusing.

[motus]

Looks good! Maybe, all one more unit test with some tunable values omitted to check that they are set to default and others are not?

[bpkroth]

Looks good! Maybe, all one more unit test with some tunable values omitted to check that they are set to default and others are not?

I think that's handled already in the test I added. I made it a little bit more explicit just now as well.