- rework toTag resolving fallback if build was not started from a tag

- fallback to retrieve `toTag` from git API (only if 2 tags are available)
  - FIX https://github.com/mikepenz/release-changelog-builder-action/issues/427
  - FIX https://github.com/mikepenz/release-changelog-builder-action/issues/433
- introduce test case to verify

src/releaseNotesBuilder.ts

@@ -1,8 +1,6 @@
 import * as core from '@actions/core'
-import * as github from '@actions/github'
 import {Configuration, DefaultConfiguration} from './configuration'
 import {Octokit} from '@octokit/rest'
-import {createCommandManager} from './gitHelper'
 import {ReleaseNotes} from './releaseNotes'
 import {Tags} from './tags'
 import {failOrError} from './utils'
@@ -23,25 +21,6 @@ export class ReleaseNotesBuilder {
   ) {}
 
   async build(): Promise<string | null> {
-    // ensure to resolve the toTag if it was not provided
-    if (!this.toTag) {
-      // if not specified try to retrieve tag from github.context.ref
-      if (github.context.ref.startsWith('refs/tags/')) {
-        this.toTag = github.context.ref.replace('refs/tags/', '')
-        core.info(
-          `🔖 Resolved current tag (${this.toTag}) from the 'github.context.ref'`
-        )
-      } else {
-        // if not specified try to retrieve tag from git
-        const gitHelper = await createCommandManager(this.repositoryPath)
-        const latestTag = await gitHelper.latestTag()
-        this.toTag = latestTag
-        core.info(
-          `🔖 Resolved current tag (${this.toTag}) from 'git rev-list --tags --skip=0 --max-count=1'`
-        )
-      }
-    }
-
     if (!this.owner) {
       failOrError(`💥 Missing or couldn't resolve 'owner'`, this.failOnError)
       return null
@@ -57,14 +36,6 @@ export class ReleaseNotesBuilder {
       core.setOutput('repo', this.repo)
       core.debug(`Resolved 'repo' as ${this.repo}`)
     }
-
-    if (!this.toTag) {
-      failOrError(`💥 Missing or couldn't resolve 'toTag'`, this.failOnError)
-      return null
-    } else {
-      core.setOutput('toTag', this.toTag)
-      core.debug(`Resolved 'toTag' as ${this.toTag}`)
-    }
     core.endGroup()
 
     // load octokit instance
@@ -72,34 +43,43 @@ export class ReleaseNotesBuilder {
       auth: `token ${this.token || process.env.GITHUB_TOKEN}`
     })
 
-    // ensure to resolve the fromTag if it was not provided specifically
-    if (!this.fromTag) {
-      core.startGroup(`🔖 Resolve previous tag`)
-      core.debug(`fromTag undefined, trying to resolve via API`)
-      const tagsApi = new Tags(octokit)
+    // ensure proper from <-> to tag range
+    core.startGroup(`🔖 Resolve tags`)
+    const tagsApi = new Tags(octokit)
+    const tagRange = await tagsApi.retrieveRange(
+      this.repositoryPath,
+      this.owner,
+      this.repo,
+      this.fromTag,
+      this.toTag,
+      this.ignorePreReleases,
+      this.configuration.max_tags_to_fetch ||
+        DefaultConfiguration.max_tags_to_fetch,
+      this.configuration.tag_resolver || DefaultConfiguration.tag_resolver
+    )
 
-      const previousTag = await tagsApi.findPredecessorTag(
-        this.repositoryPath,
-        this.owner,
-        this.repo,
-        this.toTag,
-        this.ignorePreReleases,
-        this.configuration.max_tags_to_fetch ||
-          DefaultConfiguration.max_tags_to_fetch,
-        this.configuration.tag_resolver || DefaultConfiguration.tag_resolver
-      )
-      if (previousTag == null) {
-        failOrError(
-          `💥 Unable to retrieve previous tag given ${this.toTag}`,
-          this.failOnError
-        )
-        return null
-      }
-      this.fromTag = previousTag.name
-      core.debug(`fromTag resolved via previousTag as: ${previousTag.name}`)
-      core.endGroup()
+    const thisTag = tagRange.to?.name
+    if (!thisTag) {
+      failOrError(`💥 Missing or couldn't resolve 'toTag'`, this.failOnError)
+      return null
+    } else {
+      this.toTag = thisTag
+      core.setOutput('toTag', thisTag)
+      core.debug(`Resolved 'toTag' as ${thisTag}`)
     }
 
+    const previousTag = tagRange.from?.name
+    if (previousTag == null) {
+      failOrError(
+        `💥 Unable to retrieve previous tag given ${this.toTag}`,
+        this.failOnError
+      )
+      return null
+    }
+    this.fromTag = previousTag
+    core.debug(`fromTag resolved via previousTag as: ${previousTag}`)
+    core.endGroup()
+
     const options = {
       owner: this.owner,
       repo: this.repo,

src/tags.ts

@@ -1,10 +1,16 @@
 import * as core from '@actions/core'
+import * as github from '@actions/github'
 import * as semver from 'semver'
 import {Octokit, RestEndpointMethodTypes} from '@octokit/rest'
 import {SemVer} from 'semver'
 import {TagResolver} from './configuration'
 import {createCommandManager} from './gitHelper'
 
+export interface TagResult {
+  from: TagInfo | null
+  to: TagInfo | null
+}
+
 export interface TagInfo {
   name: string
   commit: string
@@ -51,19 +57,12 @@ export class Tags {
   }
 
   async findPredecessorTag(
+    sortedTags: TagInfo[],
     repositoryPath: string,
-    owner: string,
-    repo: string,
     tag: string,
-    ignorePreReleases: boolean,
-    maxTagsToFetch: number,
-    tagResolver: TagResolver
+    ignorePreReleases: boolean
   ): Promise<TagInfo | null> {
-    const tags = sortTags(
-      await this.getTags(owner, repo, maxTagsToFetch),
-      tagResolver
-    )
-
+    const tags = sortedTags
     try {
       const length = tags.length
       if (tags.length > 1) {
@@ -102,6 +101,92 @@ export class Tags {
       return null
     }
   }
+
+  async retrieveRange(
+    repositoryPath: string,
+    owner: string,
+    repo: string,
+    fromTag: string | null,
+    toTag: string | null,
+    ignorePreReleases: boolean,
+    maxTagsToFetch: number,
+    tagResolver: TagResolver
+  ): Promise<TagResult> {
+    const tags = sortTags(
+      await this.getTags(owner, repo, maxTagsToFetch),
+      tagResolver
+    )
+
+    let resultToTag: TagInfo | null
+    let resultFromTag: TagInfo | null
+
+    // ensure to resolve the toTag if it was not provided
+    if (!toTag) {
+      // if not specified try to retrieve tag from github.context.ref
+      if (github.context.ref?.startsWith('refs/tags/') === true) {
+        toTag = github.context.ref.replace('refs/tags/', '')
+        core.info(
+          `🔖 Resolved current tag (${toTag}) from the 'github.context.ref'`
+        )
+        resultToTag = {
+          name: toTag,
+          commit: toTag
+        }
+      } else if (tags.length > 1) {
+        resultToTag = tags[0]
+        core.info(
+          `🔖 Resolved current tag (${resultToTag.name}) from the tags git API`
+        )
+      } else {
+        // if not specified try to retrieve tag from git
+        const gitHelper = await createCommandManager(repositoryPath)
+        const latestTag = await gitHelper.latestTag()
+        core.info(
+          `🔖 Resolved current tag (${latestTag}) from 'git rev-list --tags --skip=0 --max-count=1'`
+        )
+        resultToTag = {
+          name: latestTag,
+          commit: latestTag
+        }
+      }
+    } else {
+      resultToTag = {
+        name: toTag,
+        commit: toTag
+      }
+    }
+
+    // ensure toTag is specified
+    toTag = resultToTag.name
+
+    // resolve the fromTag if not defined
+    if (!fromTag) {
+      core.debug(`fromTag undefined, trying to resolve via API`)
+
+      resultFromTag = await this.findPredecessorTag(
+        tags,
+        repositoryPath,
+        toTag,
+        ignorePreReleases
+      )
+
+      if (resultFromTag != null) {
+        core.info(
+          `🔖 Resolved previous tag (${resultFromTag.name}) from the tags git API`
+        )
+      }
+    } else {
+      resultFromTag = {
+        name: fromTag,
+        commit: fromTag
+      }
+    }
+
+    return {
+      from: resultFromTag,
+      to: resultToTag
+    }
+  }
 }
 
 /*