Storyshots integrity: remove abandoned storyshots when running with -u flag

addons/storyshots/storyshots-core/src/api/integrityTestTemplate.ts

@@ -2,6 +2,52 @@
 import fs from 'fs';
 import glob from 'glob';
 import { describe, it } from 'global';
+import dedent from 'ts-dedent';
+
+declare global {
+  // eslint-disable-next-line @typescript-eslint/no-namespace,no-redeclare
+  namespace jest {
+    interface Matchers<R, T> {
+      notToBeAbandoned(stories2snapsConverter: any): R;
+    }
+  }
+}
+
+expect.extend({
+  notToBeAbandoned(storyshots, stories2snapsConverter) {
+    const abandonedStoryshots = storyshots.filter((fileName: string) => {
+      const possibleStoriesFiles = stories2snapsConverter.getPossibleStoriesFiles(fileName);
+      return !possibleStoriesFiles.some(fs.existsSync);
+    });
+
+    if (abandonedStoryshots.length === 0) {
+      return { pass: true, message: () => '' };
+    }
+
+    const formattedList = abandonedStoryshots.join('\n  ');
+
+    // See https://github.com/facebook/jest/issues/8732#issuecomment-516445064
+    // eslint-disable-next-line no-underscore-dangle
+    const isUpdate = expect.getState().snapshotState._updateSnapshot === 'all';
+    if (isUpdate) {
+      abandonedStoryshots.forEach((file: string) => fs.unlinkSync(file));
+      // eslint-disable-next-line no-console
+      console.log(dedent`
+        Removed abandoned storyshots:
+          ${formattedList}
+      `);
+      return { pass: true, message: () => '' };
+    }
+
+    return {
+      pass: false,
+      message: () => dedent`
+          Found abandoned storyshots. Run jest with -u to remove them:
+            ${formattedList}
+        `,
+    };
+  },
+});
 
 function integrityTest(integrityOptions: any, stories2snapsConverter: any) {
   if (integrityOptions === false) {
@@ -13,12 +59,7 @@ function integrityTest(integrityOptions: any, stories2snapsConverter: any) {
       const snapshotExtension = stories2snapsConverter.getSnapshotExtension();
       const storyshots = glob.sync(`**/*${snapshotExtension}`, integrityOptions);
 
-      const abandonedStoryshots = storyshots.filter(fileName => {
+      expect(storyshots).notToBeAbandoned(stories2snapsConverter);
-        const possibleStoriesFiles = stories2snapsConverter.getPossibleStoriesFiles(fileName);
-        return !possibleStoriesFiles.some(fs.existsSync);
-      });
-
-      expect(abandonedStoryshots).toEqual([]);
     });
   });
 }