feat(condition): Update conditions to support source and target key comparisons

[Mallika05]

Description

Updated the following conditions to support comparisons between source_key and target_key values.

• number_equal_to
• number_greater_than
• number_less_than
• string_equal_to
• string_greater_than
• string_less_than

Example:

sub.condition.number.less_than( settings={object: {source_key: 'a', target_key: 'z'}} )
sub.condition.string.less_than( settings={object: {source_key: 'a', target_key: 'z'}} )

Motivation and Context

This adds flexibility to accept both static values or target_key whichever is provided in the config. Static value is ignored if target_key is present in the condition. This solves the issue discussed here: #64.

How Has This Been Tested?

Added unit tests in respective files.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[Mallika05]

• feat(condition): Update conditions to support source and target key comparisons #214 👈
• main

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[jshlbrd]

The additions look good but I have an ask for changes to each function, it's slightly better to do this:

	compare := insp.conf.Value

	if insp.conf.Object.SourceKey == "" {
		f, err := strconv.ParseFloat(string(msg.Data()), 64)
		if err != nil {
			return false, err
		}

		return insp.match(f, compare), nil
	}

	target := msg.GetValue(insp.conf.Object.TargetKey)
	if target.Exists() {
		compare = target.Float()
	}

	v := msg.GetValue(insp.conf.Object.SourceKey)
	return insp.match(v.Float(), compare), nil

Instead of this:

	compare := insp.conf.Value

	target := msg.GetValue(insp.conf.Object.TargetKey)
	if target.Exists() {
		compare = target.Float()
	}

	if insp.conf.Object.SourceKey == "" {
		f, err := strconv.ParseFloat(string(msg.Data()), 64)
		if err != nil {
			return false, err
		}

		return insp.match(f, compare), nil
	}

	v := msg.GetValue(insp.conf.Object.SourceKey)
	return insp.match(v.Float(), compare), nil

If conf.Object.SourceKey is empty, then the condition is evaluating the message's content directly, so it can't do a comparison between two different values (e.g. {"foo":1.0} shouldn't be compared to 1.0 because it will always be false). We'll get a little more performance by accessing the TargetKey after that statement than before it.

If someone were to configure these functions like that, then that would be a user error (identical to this one).