feat: add pre-release increment behavior

README.md

@@ -337,6 +337,14 @@ autolabeler:
       - '/JIRA-[0-9]{1,4}/'
 ```
 
+## Pre-release increment
+
+When creating Pre-release (`prerelease: true`), you can add a pre-release identifier to increment the pre-release version number, with the `prerelease-identifer` option. It accept any string, but it's recommended to use [Semantic Versioning](https://semver.org/) pre-release identifiers (alpha, beta, rc, etc).
+
+```yml
+prerelease-identifer: 'alpha' # will create a pre-release with version number x.x.x-alpha.x
+```
+
 ## Projects that don't use Semantic Versioning
 
 If your project doesn't follow [Semantic Versioning](https://semver.org) you can still use Release Drafter, but you may want to set the `version-template` option to customize how the `$NEXT_{PATCH,MINOR,MAJOR}_VERSION` environment variables are generated.

lib/default-config.js

@@ -7,7 +7,7 @@ const DEFAULT_CONFIG = Object.freeze({
   'change-template': `* $TITLE (#$NUMBER) @$AUTHOR`,
   'change-title-escapes': '',
   'no-changes-template': `* No changes`,
-  'version-template': `$MAJOR.$MINOR.$PATCH`,
+  'version-template': `$MAJOR.$MINOR.$PATCH$PRERELEASE`,
   'version-resolver': {
     major: { labels: [] },
     minor: { labels: [] },
@@ -25,6 +25,7 @@ const DEFAULT_CONFIG = Object.freeze({
   'sort-by': SORT_BY.mergedAt,
   'sort-direction': SORT_DIRECTIONS.descending,
   prerelease: false,
+  'prerelease-identifier': '',
   'filter-by-commitish': false,
   commitish: '',
   'category-template': `## $TITLE`,

lib/releases.js

@@ -281,12 +281,22 @@ const generateChangeLog = (mergedPullRequests, config) => {
   return changeLog.join('').trim()
 }
 
-const resolveVersionKeyIncrement = (mergedPullRequests, config) => {
+const resolveVersionKeyIncrement = (
+  mergedPullRequests,
+  config,
+  isPreRelease
+) => {
   const priorityMap = {
     patch: 1,
     minor: 2,
     major: 3,
   }
+
+  // Should increment pre-release version
+  if (isPreRelease && config['prerelease-identifier']) {
+    return 'prerelease'
+  }
+
   const labelToKeyMap = Object.fromEntries(
     Object.keys(priorityMap)
       .flatMap((key) => [
@@ -340,14 +350,21 @@ const generateReleaseInfo = ({
     config.replacers
   )
 
+  const versionKeyIncrement = resolveVersionKeyIncrement(
+    mergedPullRequests,
+    config,
+    isPreRelease
+  )
+
   const versionInfo = getVersionInfo(
     lastRelease,
     config['version-template'],
     // Use the first override parameter to identify
     // a version, from the most accurate to the least
     version || tag || name,
-    resolveVersionKeyIncrement(mergedPullRequests, config),
-    config['tag-prefix']
+    versionKeyIncrement,
+    config['tag-prefix'],
+    config['prerelease-identifier']
   )
 
   if (versionInfo) {

lib/schema.js

@@ -76,6 +76,9 @@ const schema = (context) => {
         .default(DEFAULT_CONFIG['sort-direction']),
 
       prerelease: Joi.boolean().default(DEFAULT_CONFIG.prerelease),
+      'prerelease-identifier': Joi.string()
+        .allow('')
+        .default(DEFAULT_CONFIG['prerelease-identifier']),
 
       'filter-by-commitish': Joi.boolean().default(
         DEFAULT_CONFIG['filter-by-commitish']

lib/versions.js

@@ -6,15 +6,18 @@ const splitSemVersion = (input, versionKey = 'version') => {
   }
 
   const version = input.inc
-    ? semver.inc(input[versionKey], input.inc, true)
+    ? semver.inc(input[versionKey], input.inc, true, input.prereleaseIdentifier)
     : input[versionKey].version
 
+  const prereleaseVersion = semver.prerelease(version)?.join('.') || ''
+
   return {
     ...input,
     version,
     $MAJOR: semver.major(version),
     $MINOR: semver.minor(version),
     $PATCH: semver.patch(version),
+    $PRERELEASE: prereleaseVersion ? `-${prereleaseVersion}` : '',
     $COMPLETE: version,
   }
 }
@@ -29,6 +32,7 @@ const defaultVersionInfo = {
     $MAJOR: 1,
     $MINOR: 0,
     $PATCH: 0,
+    $PRERELEASE: '',
   },
   $NEXT_MINOR_VERSION: {
     version: '0.1.0',
@@ -39,6 +43,7 @@ const defaultVersionInfo = {
     $MAJOR: 0,
     $MINOR: 1,
     $PATCH: 0,
+    $PRERELEASE: '',
   },
   $NEXT_PATCH_VERSION: {
     version: '0.1.0',
@@ -49,6 +54,19 @@ const defaultVersionInfo = {
     $MAJOR: 0,
     $MINOR: 1,
     $PATCH: 0,
+    $PRERELEASE: '',
+  },
+  $NEXT_PRERELEASE_VERSION: {
+    version: '0.1.0-rc.0',
+    template: '$MAJOR.$MINOR.$PATCH$PRERELEASE',
+    inputVersion: null,
+    versionKeyIncrement: 'prerelease',
+    inc: 'prerelease',
+    prereleaseIdentifier: 'rc',
+    $MAJOR: 0,
+    $MINOR: 1,
+    $PATCH: 0,
+    $PRERELEASE: '-rc.0',
   },
   $INPUT_VERSION: null,
   $RESOLVED_VERSION: {
@@ -60,6 +78,7 @@ const defaultVersionInfo = {
     $MAJOR: 0,
     $MINOR: 1,
     $PATCH: 0,
+    $PRERELEASE: '',
   },
 }
 
@@ -113,6 +132,11 @@ const getTemplatableVersion = (input) => {
       inc: 'patch',
       template: '$PATCH',
     }),
+    $NEXT_PRERELEASE_VERSION: splitSemVersion({
+      ...input,
+      inc: 'prerelease',
+      template: '$PRERELEASE',
+    }),
     $INPUT_VERSION: splitSemVersion(input, 'inputVersion'),
     $RESOLVED_VERSION: splitSemVersion({
       ...input,
@@ -156,7 +180,8 @@ const getVersionInfo = (
   template,
   inputVersion,
   versionKeyIncrement,
-  tagPrefix
+  tagPrefix,
+  prereleaseIdentifier
 ) => {
   const version = coerceVersion(release, tagPrefix)
   inputVersion = coerceVersion(inputVersion, tagPrefix)
@@ -171,6 +196,7 @@ const getVersionInfo = (
       template,
       inputVersion,
       versionKeyIncrement,
+      prereleaseIdentifier,
     }),
   }
 }

schema.json

@@ -32,7 +32,7 @@
       "type": "string"
     },
     "version-template": {
-      "default": "$MAJOR.$MINOR.$PATCH",
+      "default": "$MAJOR.$MINOR.$PATCH$PRERELEASE",
       "type": "string"
     },
     "name-template": {
@@ -117,6 +117,18 @@
       "default": false,
       "type": "boolean"
     },
+    "prerelease-identifier": {
+      "anyOf": [
+        {
+          "type": "string",
+          "enum": [""]
+        },
+        {
+          "default": "",
+          "type": "string"
+        }
+      ]
+    },
     "filter-by-commitish": {
       "default": false,
       "type": "boolean"

test/fixtures/config/config-with-prerelease-identifier.yml

@@ -0,0 +1,4 @@
+template: This is a Pre-release with identifier.
+name-template: 'v$RESOLVED_VERSION'
+tag-template: 'v$RESOLVED_VERSION'
+prerelease-identifier: alpha

test/index.test.js

@@ -4,7 +4,7 @@ const { getConfigMock } = require('./helpers/config-mock')
 const releaseDrafter = require('../index')
 const mockedEnv = require('mocked-env')
 const pino = require('pino')
-const Stream = require('stream')
+const Stream = require('node:stream')
 const pushPayload = require('./fixtures/push.json')
 const pushTagPayload = require('./fixtures/push-tag.json')
 const releasePayload = require('./fixtures/release.json')
@@ -2610,6 +2610,20 @@ describe('release-drafter', () => {
           }
         )
       })
+
+      it('resolves tag with incremented pre-release identifier', async () => {
+        return overridesTest(
+          {
+            prerelease: 'true',
+            configName: 'config-with-prerelease-identifier.yml',
+          },
+          {
+            prerelease: true,
+            name: 'v2.0.1-alpha.0',
+            tag_name: 'v2.0.1-alpha.0',
+          }
+        )
+      })
     })
 
     describe('with input prerelease: false', () => {