diff: use overlays from previous version instead of using same overlays

package.json

@@ -44,7 +44,7 @@
     "@actions/github": "^5.1.1",
     "@actions/io": "^1.1.3",
     "@octokit/types": "^14.1.0",
-    "bump-cli": "^2.9.9"
+    "bump-cli": "^2.9.10"
   },
   "devDependencies": {
     "@github/local-action": "^5.1.0",

src/github.ts

@@ -100,6 +100,28 @@ export class Repo {
     }
   }
 
+  /* WARNING: you need to first call .getBaseFile to have base files
+   * available in the tmpDir */
+  async getBaseOverlays(overlays: string[] | undefined): Promise<string[]> {
+    const tmpDir = 'tmp/';
+
+    const tmpOverlays: (string | undefined)[] = await Promise.all(
+      (overlays || []).map(async (overlayFile) => {
+        if (!overlayFile) return undefined;
+
+        // All files of the “previous” version are in the tmp/ dir
+        // so we take all the previous versions' overlay files (if
+        // they exist)
+        const tmpOverlay = `${tmpDir}${overlayFile}`;
+        if (await fsExists(tmpOverlay)) {
+          return tmpOverlay;
+        }
+      }),
+    );
+
+    return tmpOverlays.filter((e) => e) as string[];
+  }
+
   async createOrUpdateComment(body: string, digest: string): Promise<void> {
     if (!this.prNumber) {
       core.info('Not a pull request, nothing more to do.');

src/main.ts

@@ -69,17 +69,32 @@ export async function run(): Promise<void> {
       case 'diff':
         const repo = new Repo(doc, hub, branch);
         let file1 = await repo.getBaseFile(file);
+        const overlays1: string[] | undefined =
+          (await repo.getBaseOverlays(overlays)) || [];
         let file2: string | undefined;
+        let overlays2: string[] | undefined;
 
         if (file1) {
+          overlays2 = overlays;
           file2 = file;
         } else {
           file1 = file;
         }
 
         const config = await Config.load(oclifConfig);
         await new bump.Diff.Diff(config)
-          .run(file1, file2, doc, hub, branch, token, 'markdown', expires, overlays)
+          .run(
+            file1,
+            file2,
+            doc,
+            hub,
+            branch,
+            token,
+            'markdown',
+            expires,
+            overlays1,
+            overlays2,
+          )
           .then((result: bump.DiffResponse | undefined) => {
             if (result) {
               diff.run(result, repo).catch(handleErrors);

tests/fixtures/repo.ts

@@ -2,12 +2,14 @@ import type * as repo from '../../src/github.js';
 import { jest } from '@jest/globals';
 
 export const mockGetBaseFile = jest.fn<repo.Repo['getBaseFile']>();
+export const mockGetBaseOverlays = jest.fn<repo.Repo['getBaseOverlays']>();
 export const mockCreateOrUpdateComment = jest.fn<repo.Repo['createOrUpdateComment']>();
 export const mockDeleteExistingComment = jest.fn<repo.Repo['deleteExistingComment']>();
 export const Repo = jest.fn().mockImplementation(() => {
   return {
     doc: 'my-doc',
     getBaseFile: mockGetBaseFile,
+    getBaseOverlays: mockGetBaseOverlays,
     createOrUpdateComment: mockCreateOrUpdateComment,
     deleteExistingComment: mockDeleteExistingComment,
   };

tests/github.test.ts

@@ -63,6 +63,17 @@ describe('github.ts', () => {
     });
   });
 
+  describe('getBaseOverlays function', () => {
+    test('Returns the given list of filenames prepended with the tmpDir', async () => {
+      common.fsExists.mockResolvedValue(true);
+
+      const repo = new Repo('hello');
+      const baseOverlays = await repo.getBaseOverlays(['overlay.yml']);
+
+      expect(baseOverlays).toStrictEqual([`tmp/overlay.yml`]);
+    });
+  });
+
   describe('createOrUpdateComment function', () => {
     // Mock GitHub API
     const nockScope = nock('https://api.github.com');

tests/main.test.ts

@@ -46,6 +46,7 @@ describe('main.ts', () => {
     stdout.stop();
     stdout.start();
     repo.mockGetBaseFile.mockReset();
+    repo.mockGetBaseOverlays.mockReset();
   });
 
   afterEach(() => {
@@ -292,6 +293,7 @@ one
         'markdown',
         '',
         [],
+        undefined,
       );
     });
 
@@ -332,6 +334,7 @@ one
         'markdown',
         '',
         [],
+        undefined,
       );
     });
 
@@ -370,6 +373,7 @@ one
         'markdown',
         '',
         [],
+        undefined,
       );
     });
 
@@ -409,6 +413,7 @@ one
         'markdown',
         '',
         [],
+        [],
       );
     });
 
@@ -436,6 +441,7 @@ one
         'markdown',
         expect.anything(),
         [],
+        [],
       );
     });
 
@@ -449,6 +455,7 @@ one
       });
       // Mock base file from PR
       repo.mockGetBaseFile.mockResolvedValue('my-base-file-to-diff.yml');
+      repo.mockGetBaseOverlays.mockResolvedValue(['my-base-overlays.yml']);
 
       await run();
 
@@ -461,6 +468,7 @@ one
         expect.anything(),
         'markdown',
         expect.anything(),
+        ['my-base-overlays.yml'],
         ['overlay1.yml', 'overlay2.yml'],
       );
     });
@@ -502,6 +510,7 @@ one
         'markdown',
         expect.anything(),
         [],
+        undefined,
       );
     });
   });