ref(nextjs): Simplify adding default integrations when initializing SDK

[lobsterkatie]

While working on adding a RequestData integration to the nextjs SDK, I found that the functions we use to set default integrations in the SDK were a little hard to parse, primarily because of a docstring that didn't make any sense and vague and/or slightly inaccurate function and variable names. We also have been making things more complicated than necessary, in that

a) The existing functions in utils/userIntegrations.ts use the given default integration instance if no user instance is found. Meanwhile, the two index files do the same in the case that no user integrations are provided at all. But those two conditions aren't logically independent, so by simply providing a default (empty) value for the second case, we can rely on the first check to ensure the default instance is used. (See the now-removed if (options.integrations) check in both of the index files.)

b) The options we want to force onto any user instance we find have been living in a nested object which really doesn’t need to be nested. (See the Options - now ForcedIntegrationOptions - type in utils/userIntegrations.ts.)

c) We've essentially been manually implementing Array.find, which there's no reason for us to do. (See the for-loop in addIntegrationToArray - now addOrUpdateIntegrationInArray - in utils/userIntegrations.ts.)

This fixes those problems, rewrites the docstring, and renames a bunch of variables. It also

• Reorganizes the tests testing the adding of default integrations and refactors them to stop depending on the order or size of the eventual integrations array when testing an individual integration type.
• Fixes a small regex bug in setNestedKey.

For ease of reviewing, the docstring/renaming changes have been separated into a separate commit from the logic changes, test reorg, and bugfix.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	19.46 KB (0%)
@sentry/browser - ES5 CDN Bundle (minified)	60.11 KB (0%)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	18.04 KB (0%)
@sentry/browser - ES6 CDN Bundle (minified)	53.03 KB (0%)
@sentry/browser - Webpack (gzipped + minified)	19.83 KB (0%)
@sentry/browser - Webpack (minified)	64.42 KB (0%)
@sentry/react - Webpack (gzipped + minified)	19.85 KB (0%)
@sentry/nextjs Client - Webpack (gzipped + minified)	44.84 KB (-0.07% 🔽)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	25.97 KB (0%)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	24.35 KB (0%)

[AbhiPrasad]

With this API, couldn't we collide if integrations have the same option name?

[lobsterkatie]

It's the same API as before, just a slightly simpler implementation - it still filters on integration name. See the const userInstance = userIntegrations.find(integration => integration.name === defaultIntegrationInstance.name); line in addOrUpdateIntegrationInArray.

What it doesn't protect against is duplicates (the way the main integration logic does), but hopefully users won't be giving us two copies of the same integration.