Snapshot testing for the articles transformer

.gitattributes

@@ -0,0 +1,3 @@
+pipeline/test/prismic-snapshots/*.json linguist-generated=true
+*.shot linguist-language=Jest-Snapshot
+*.shot linguist-generated

pipeline/package.json

@@ -6,6 +6,7 @@
   "scripts": {
     "package": "./package.sh",
     "reindex": "ts-node src/local.ts",
+    "update-prismic-snapshots": "ts-node test/update-prismic-snapshots.ts",
     "test": "jest"
   },
   "dependencies": {

pipeline/test/fixtures/forEachPrismicSnapshot.ts

@@ -0,0 +1,40 @@
+import fs from "node:fs";
+import path from "node:path";
+import { test } from "@jest/globals";
+import type { Global as JestGlobal } from "@jest/types";
+import { ContentType } from "../../src/types";
+import { PrismicDocument } from "@prismicio/types";
+
+// Hold snapshots in memory rather than reading from the filesystem for every test
+const snapshotCache = new Map<string, any>();
+const contentTypesCache = new Map<ContentType, string[]>();
+
+const dataDir = path.resolve(__dirname, "../prismic-snapshots");
+
+const getSnapshot = <T>(name: string): T => {
+  if (snapshotCache.has(name)) {
+    return snapshotCache.get(name);
+  }
+  return JSON.parse(
+    fs.readFileSync(path.resolve(dataDir, name), { encoding: "utf-8" })
+  );
+};
+
+const snapshotNamesForContentType = (contentType: ContentType): string[] =>
+  contentTypesCache.get(contentType) ??
+  fs.readdirSync(dataDir).filter((f) => f.endsWith(`${contentType}.json`));
+
+const forEachPrismicSnapshot = <T extends PrismicDocument>(
+  ...contentTypes: ContentType[]
+) => {
+  const snapshots = contentTypes
+    .flatMap(snapshotNamesForContentType)
+    .map(getSnapshot<T>);
+
+  return <EachFn extends JestGlobal.TestFn | JestGlobal.BlockFn>(
+    description: string,
+    testCase: (snapshot: T) => ReturnType<EachFn>
+  ) => test.each(snapshots)(`${description} (document: $type/$id)`, testCase);
+};
+
+export default forEachPrismicSnapshot;