From 3083a1c27b164b7ce7b7b0be110cdf4dfe025dc0 Mon Sep 17 00:00:00 2001
From: Robert Jackson <rjackson@linkedin.com>
Date: Fri, 24 Apr 2020 10:43:12 -0400
Subject: [PATCH 1/2] Ensure `CHANGELOG.md` has correct version when
 `git.tagName` is not present

Previously we would call `format(null, { version })` which returns `''`.
---
 index.js | 10 +++-------
 test.js  |  6 +++++-
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/index.js b/index.js
index 706ba36..a538da9 100644
--- a/index.js
+++ b/index.js
@@ -23,7 +23,9 @@ module.exports = class LernaChangelogGeneratorPlugin extends Plugin {
 
   get nextVersion() {
     let { version } = this.config.getContext();
-    let nextVersion = this.getTagNameFromVersion(version);
+
+    let tagName = this.config.getContext('git.tagName');
+    let nextVersion = tagName ? format(tagName, { version }) : version;
 
     return nextVersion;
   }
@@ -33,12 +35,6 @@ module.exports = class LernaChangelogGeneratorPlugin extends Plugin {
     return this.changelog;
   }
 
-  getTagNameFromVersion(version) {
-    let tagName = this.config.getContext('git.tagName');
-
-    return format(tagName, { version });
-  }
-
   async getTagForHEAD() {
     try {
       return await this.exec('git describe --tags --abbrev=0', { options: { write: false } });
diff --git a/test.js b/test.js
index 824b369..d3849ef 100644
--- a/test.js
+++ b/test.js
@@ -95,7 +95,8 @@ test('it invokes lerna-changelog', async (t) => {
 });
 
 test('it honors custom git.tagName formatting', async (t) => {
-  let plugin = buildPlugin();
+  let infile = tmp.fileSync().name;
+  let plugin = buildPlugin({ infile });
 
   plugin.config.setContext({ git: { tagName: 'v${version}' } });
 
@@ -105,6 +106,9 @@ test('it honors custom git.tagName formatting', async (t) => {
     ['git describe --tags --abbrev=0', { write: false }],
     [`${LERNA_PATH} --next-version=Unreleased --from=v1.0.0`, { write: false }],
   ]);
+
+  const changelog = fs.readFileSync(infile, { encoding: 'utf8' });
+  t.is(changelog, `### v1.0.1 (2020-03-18)\n\nThe changelog\n\n`);
 });
 
 test('it sets the changelog without version information onto the config', async (t) => {

From 1d52bd4bb48d8ebadc0d9ad99182a60271cd427b Mon Sep 17 00:00:00 2001
From: Robert Jackson <rjackson@linkedin.com>
Date: Fri, 24 Apr 2020 10:44:19 -0400
Subject: [PATCH 2/2] Ensure that even if there are no changes, we add
 _something_ to `CHANGELOG.md.`

---
 index.js | 17 ++++++++++++-----
 test.js  | 12 ++++++++++++
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/index.js b/index.js
index a538da9..22f5a13 100644
--- a/index.js
+++ b/index.js
@@ -12,6 +12,12 @@ const LERNA_PATH = require.resolve('lerna-changelog/bin/cli');
 // and this makes it much simpler
 const UNRELEASED = 'Unreleased';
 
+function getToday() {
+  const date = new Date().toISOString();
+
+  return date.slice(0, date.indexOf('T'));
+}
+
 module.exports = class LernaChangelogGeneratorPlugin extends Plugin {
   async init() {
     let from = (await this.getTagForHEAD()) || (await this.getFirstCommit());
@@ -63,8 +69,11 @@ module.exports = class LernaChangelogGeneratorPlugin extends Plugin {
     return changelog;
   }
 
-  async processChangelog(_changelog) {
-    let changelog = _changelog.replace(UNRELEASED, this.nextVersion);
+  async processChangelog() {
+    // this is populated in `init`
+    let changelog = this.changelog
+      ? this.changelog.replace(UNRELEASED, this.nextVersion)
+      : `## ${this.nextVersion} (${getToday()})`;
 
     let finalChangelog = await this.reviewChangelog(changelog);
 
@@ -159,9 +168,7 @@ module.exports = class LernaChangelogGeneratorPlugin extends Plugin {
   }
 
   async beforeRelease() {
-    // this is populated in `init`
-    let changelog = this.changelog || '';
-    let processedChangelog = await this.processChangelog(changelog);
+    let processedChangelog = await this.processChangelog();
 
     this.debug({ changelog: processedChangelog });
 
diff --git a/test.js b/test.js
index d3849ef..f23b055 100644
--- a/test.js
+++ b/test.js
@@ -121,6 +121,18 @@ test('it sets the changelog without version information onto the config', async
   t.is(changelog, 'The changelog');
 });
 
+test('it prints something to CHANGELOG.md when lerna-changelog returns no content', async (t) => {
+  let infile = tmp.fileSync().name;
+  let plugin = buildPlugin({ infile });
+
+  plugin.responses[`${LERNA_PATH} --next-version=Unreleased --from=v1.0.0`] = '';
+
+  await runTasks(plugin);
+
+  const changelog = fs.readFileSync(infile, { encoding: 'utf8' });
+  t.is(changelog, `## 1.0.1 (${new Date().toISOString().slice(0, 10)})\n\n`);
+});
+
 test('it uses the first commit when no tags exist', async (t) => {
   let infile = tmp.fileSync().name;