Follow-up from "Fix authoritative source of truth for diff files when loading batched diffs"
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The following discussion from !23274 should be addressed:
- [ ] @pslaughter started a [discussion](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/23274#note_286550250): (+1 comment)
> **suggestion (non-blocking):** This part is a bit awkward because our main motivation for calling `prepareDiffData` in this context is to initialize our `diff` object (not necessarily combine or dedupe anything). This is a smell that our `prepareDiffData` is not cohesive and is doing too much (i.e. merging with previous files **and** setting up the object given to it).
>
> IMHO, we could simplify things a bit if we split up `prepareDiffData` into
>
> ```javascript
> import { flow } from 'lodash';
>
> export const prepareDiffFile = flow([
> ensureBasicDiffFileLines,
> prepareDiffFileLines,
> finalizeDiffFile,
> ]);
>
> export function prepareDiffData(files = []) {
> return files.map(prepareDiffFile);
> }
>
> export function mergeDiffFiles(newFiles, priorFiles = []) {
> return deduplicateFilesList([...priorFiles, ...newFiles]);
> }
> ```
>
> If you think something like this is helpful, can we handle it here or in a follow-up?
issue