diff: make sure to differentiate No Change vs Content change only

This commit makes sure to have a different behavior during a diff
between a No Change at all result, vs a No Content Change result.

Before this commit we would only display a “No diff found” message in
the GH action logs.

With this new commit, if there's a content change detected we now
publish a comment containing a link to be able to preview the change.

src/common.ts

@@ -19,10 +19,10 @@ function extractBumpDigest(docDigest: string, body: string): string | undefined
   return (body.match(bumpDiffRegexp(docDigest)) || []).pop();
 }
 
-function shaDigest(texts: string[]): string {
+function shaDigest(texts: (string | undefined)[]): string {
   const hash = crypto.createHash('sha1');
 
-  texts.forEach((text) => hash.update(text, 'utf8'));
+  texts.forEach((text) => text && hash.update(text, 'utf8'));
 
   return hash.digest('hex');
 }

src/diff.ts

@@ -3,7 +3,7 @@ import { DiffResponse } from 'bump-cli';
 import { bumpDiffComment, shaDigest } from './common';
 
 export async function run(diff: DiffResponse, repo: Repo): Promise<void> {
-  const digestContent = [diff.markdown!];
+  const digestContent = [diff.markdown];
   if (diff.public_url) {
     digestContent.push(diff.public_url);
   }
@@ -16,18 +16,26 @@ export async function run(diff: DiffResponse, repo: Repo): Promise<void> {
 function buildCommentBody(docDigest: string, diff: DiffResponse, digest: string) {
   const emptySpace = '';
   const poweredByBump = '> _Powered by [Bump.sh](https://bump.sh)_';
+  const text = diff.markdown || 'No structural change, nothing to display.';
 
   return [title(diff)]
-    .concat([emptySpace, diff.markdown!])
+    .concat([emptySpace, text])
     .concat([viewDiffLink(diff), poweredByBump, bumpDiffComment(docDigest, digest)])
     .join('\n');
 }
 
 function title(diff: DiffResponse): string {
-  const commentTitle = '🤖 API change detected:';
+  const structureTitle = '🤖 API structural change detected:';
+  const contentTitle = 'ℹ️ API content change detected:';
   const breakingTitle = '🚨 Breaking API change detected:';
 
-  return diff.breaking ? breakingTitle : commentTitle;
+  if (diff.breaking) {
+    return breakingTitle;
+  } else if (diff.markdown) {
+    return structureTitle;
+  } else {
+    return contentTitle;
+  }
 }
 
 function viewDiffLink(diff: DiffResponse): string {

src/main.ts

@@ -68,10 +68,10 @@ async function run(): Promise<void> {
         await new bump.Diff(config)
           .run(file1, file2, doc, hub, branch, token, 'markdown', expires)
           .then((result: bump.DiffResponse | undefined) => {
-            if (result && 'markdown' in result) {
+            if (result) {
               diff.run(result, repo).catch(handleErrors);
             } else {
-              core.info('No diff found, nothing more to do.');
+              core.info('No changes detected, nothing more to do.');
               repo.deleteExistingComment();
             }
 

tests/diff.test.ts

@@ -26,13 +26,39 @@ test('test github diff run process', async () => {
   await diff.run(result, repo);
 
   expect(mockedInternalRepo.prototype.createOrUpdateComment).toHaveBeenCalledWith(
-    `🤖 API change detected:
+    `🤖 API structural change detected:
 
 * one
 * two
 * three
 
 
+[Preview documentation](https://bump.sh/doc/my-doc/changes/654)
+
+> _Powered by [Bump.sh](https://bump.sh)_
+<!-- Bump.sh digest=${digest} doc=undefined -->`,
+    digest,
+  );
+});
+
+test('test github diff with no structural change', async () => {
+  const result: bump.DiffResponse = {
+    id: '123abc',
+    public_url: 'https://bump.sh/doc/my-doc/changes/654',
+    breaking: false,
+  };
+  const digest = '3999a0fe6ad27841bd6342128f7028ab2cea1c57';
+
+  expect(mockedInternalRepo).not.toHaveBeenCalled();
+
+  const repo = new Repo('');
+  await diff.run(result, repo);
+
+  expect(mockedInternalRepo.prototype.createOrUpdateComment).toHaveBeenCalledWith(
+    `ℹ️ API content change detected:
+
+No structural change, nothing to display.
+
 [Preview documentation](https://bump.sh/doc/my-doc/changes/654)
 
 > _Powered by [Bump.sh](https://bump.sh)_
@@ -91,7 +117,7 @@ test('test github diff without public url', async () => {
   await diff.run(result, repo);
 
   expect(mockedInternalRepo.prototype.createOrUpdateComment).toHaveBeenCalledWith(
-    `🤖 API change detected:
+    `🤖 API structural change detected:
 
 * one
 * two

tests/main.test.ts

@@ -367,3 +367,38 @@ test('test action run diff with internal exception', async () => {
   );
   expect(mockedInternalDiff.run).toHaveBeenCalledWith(diffExample, expect.any(Repo));
 });
+
+test('test action run diff with no change', async () => {
+  const spyInfo = jest.spyOn(core, 'info');
+
+  mockedDiff.prototype.run.mockResolvedValue(undefined);
+  expect(mockedDiff.prototype.run).not.toHaveBeenCalled();
+  expect(mockedInternalDiff.run).not.toHaveBeenCalled();
+  mockedInternalRepo.prototype.getBaseFile.mockResolvedValue('my-base-file-to-diff.yml');
+
+  const restore = mockEnv({
+    INPUT_FILE: 'my-file-to-diff.yml',
+    INPUT_COMMAND: 'diff',
+    INPUT_FAIL_ON_BREAKING: 'true',
+  });
+
+  await main();
+
+  restore();
+
+  expect(spyInfo).toHaveBeenCalledWith(
+    expect.stringMatching('No changes detected, nothing more to do.'),
+  );
+
+  expect(mockedDiff.prototype.run).toHaveBeenCalledWith(
+    'my-base-file-to-diff.yml',
+    'my-file-to-diff.yml',
+    expect.anything(),
+    expect.anything(),
+    expect.anything(),
+    expect.anything(),
+    'markdown',
+    expect.anything(),
+  );
+  expect(mockedInternalDiff.run).not.toHaveBeenCalled();
+});