Add support for devOnlyAssignments

[janicduplessis]

Closes #93

Add support for https://github.com/facebook/relay/blob/f8585ab4f90f2e707d5555c9f7b423de3ea553bd/packages/relay-compiler/language/RelayLanguagePluginInterface.js#L176.

My main questions is whether this is a breaking change or not and if it should be enabled by default. Also should we make the dev check process.env.NODE_ENV !== 'production' configurable?

[alloy]

Oh! I didn’t even know of this. Great stuff, I guess we should also update the documentation upstream on the interface then.

Ok, so what’s interesting is that upstream appears to always set it when queries are being persisted, so perhaps they strip it out on builds? [Scratch that, as stated below I was confused about what file I was looking at, it actually looks like the OSS version of formatGeneratedModule does nothing with the passed in devOnlyAssignments, so I guess FB has an internal fork?] That would actually be more suitable to our [Artsy’s] setup, as we check our artefacts in and having different artefacts for dev vs prod would lead to a dirty SCM checkout.

I’m not sure if a Babel transform already exists that would strip property initializers from objects–it would certainly not be hard to create–but I do think that perhaps that could lead to a better situation where the person in charge of builds can configure dev vs prod differences in a single place (babel config, in this case).

What do you think?

[alloy]

I think we should just mimic the upstream behaviour, which is to always do this when queries are being persisted https://github.com/facebook/relay/blob/42033ebcc298af7e8ed90632b70077b7545a282d/packages/relay-compiler/codegen/writeRelayGeneratedFile.js#L107-L133

[alloy]

As per the upstream behaviour, the actual query text should be taken from the generated AST node: https://github.com/facebook/relay/blob/42033ebcc298af7e8ed90632b70077b7545a282d/packages/relay-compiler/codegen/writeRelayGeneratedFile.js#L110

[alloy]

Scratch this, I wasn’t paying attention to the filename, as per my below comment.

[alloy]

Ah, hmm, I now see that the main difference is that upstream is doing this work in writeRelayGeneratedFile, instead of formatGeneratedModule 🤔

I wonder if we could move the Flow type annotation behaviour upstream to formatGeneratedModule instead, because writeRelayGeneratedFile shouldn’t really know about Flow specifically. /cc @jstejada

For now, though, I guess your string replace is the best we can do.