Allow configuring RegEx patterns for copySourcePRLabels

docs/config-file-options.md

@@ -490,11 +490,15 @@ Assign the same reviewers to the target pull request that were assigned to the o
 
 #### `copySourcePRLabels`
 
-Copies all labels from the original (source) pull request to the backport (target) pull request.
+Copies labels from the original (source) pull request to the backport (target) pull request.
+Can be either a boolean or an array of strings. When set to `true`, _all_ labels from the source PR are copied to the target PR.
+When an array of strings is configured, each string is used as a RegEx pattern and will be compared to each label of the source PR.
+If the label on the source PR matches at least one configured string, it will be copied to the target PR.
 
+Default: `false`
 ```json
 {
-  "copySourcePRLabels": false
+  "copySourcePRLabels": ["^Team:.*", "^:.*", "^>.*"]
 }
 ```
 

src/lib/cherrypickAndCreateTargetPullRequest/copySourcePullRequestLabels.test.ts

@@ -0,0 +1,72 @@
+import { Commit } from '../../entrypoint.api';
+import { ValidConfigOptions } from '../../options/options';
+import { getLabelsToCopy } from './copySourcePullRequestLabels';
+
+describe('getLabelsToCopy', () => {
+  it('should return an empty array when no commits have sourcePullRequest', () => {
+    const commits = [{ sourcePullRequest: null }] as unknown as Commit[];
+    const options = { copySourcePRLabels: true } as ValidConfigOptions;
+    const result = getLabelsToCopy(commits, options);
+    expect(result).toEqual([]);
+  });
+
+  it('copies all labels except backport labels when copySourcePRLabels is boolean', () => {
+    const commits = [
+      {
+        sourcePullRequest: {
+          title: 'My pr title',
+          labels: ['a', 'b', 'my-backport-label'],
+          number: 1,
+        },
+        targetPullRequestStates: [{ label: 'my-backport-label' } as any],
+      } as unknown as Commit,
+    ];
+
+    const options = {
+      copySourcePRLabels: true,
+    } as unknown as ValidConfigOptions;
+
+    const result = getLabelsToCopy(commits, options);
+    expect(result).toEqual(['a', 'b']);
+  });
+
+  it('copies labels using regex patterns when copySourcePRLabels is string array', () => {
+    const commits = [
+      {
+        sourcePullRequest: {
+          title: 'PR',
+          labels: ['feat:new', 'chore', 'important-bug'],
+          number: 2,
+        },
+        targetPullRequestStates: [],
+      } as unknown as Commit,
+    ];
+
+    const options = {
+      copySourcePRLabels: ['^feat', 'bug$'],
+    } as unknown as ValidConfigOptions;
+
+    const result = getLabelsToCopy(commits, options);
+    expect(result).toEqual(['feat:new', 'important-bug']);
+  });
+
+  it('handles multiple commits and flattens results', () => {
+    const commits = [
+      {
+        sourcePullRequest: { title: 'PR1', labels: ['x'], number: 3 },
+        targetPullRequestStates: [],
+      } as unknown as Commit,
+      {
+        sourcePullRequest: { title: 'PR2', labels: ['y'], number: 4 },
+        targetPullRequestStates: [],
+      } as unknown as Commit,
+    ];
+
+    const options = {
+      copySourcePRLabels: true,
+    } as unknown as ValidConfigOptions;
+
+    const result = getLabelsToCopy(commits, options);
+    expect(result).toEqual(['x', 'y']);
+  });
+});

src/lib/cherrypickAndCreateTargetPullRequest/copySourcePullRequestLabels.ts

@@ -1,3 +1,4 @@
+import { isArray } from 'lodash';
 import { ValidConfigOptions } from '../../options/options';
 import { addLabelsToPullRequest } from '../github/v3/addLabelsToPullRequest';
 import { Commit } from '../sourceCommit/parseSourceCommit';
@@ -7,22 +8,41 @@ export async function copySourcePullRequestLabelsToTargetPullRequest(
   commits: Commit[],
   pullNumber: number,
 ) {
-  const labels = getNonBackportLabels(commits);
+  const labels = getLabelsToCopy(commits, options);
   if (labels.length > 0) {
     await addLabelsToPullRequest({ ...options, pullNumber, labels });
   }
 }
 
-function getNonBackportLabels(commits: Commit[]) {
+export function getLabelsToCopy(
+  commits: Commit[],
+  options: ValidConfigOptions,
+) {
   return commits.flatMap((commit) => {
     if (!commit.sourcePullRequest) {
       return [];
     }
 
     const backportLabels = commit.targetPullRequestStates.map((pr) => pr.label);
-    const labels = commit.sourcePullRequest.labels.filter(
-      (label) => !backportLabels.includes(label),
-    );
+    const labels = commit.sourcePullRequest.labels.filter((label) => {
+      // If `copySourcePRLabels` is a boolean, it must be true to reach this method.
+      // Therefore, we simply copy all labels from the source PR that aren't already on the target PR.
+      const copySourcePRLabels = options.copySourcePRLabels;
+      if (copySourcePRLabels === true) {
+        const isBackportLabel = backportLabels.includes(label);
+        return !isBackportLabel;
+      }
+
+      // Otherwise, it's an array of regex patterns.
+      if (isArray(copySourcePRLabels)) {
+        return copySourcePRLabels.some((sourceLabel) =>
+          label.match(new RegExp(sourceLabel)),
+        );
+      }
+      throw new Error(
+        `Unexpected type of copySourcePRLabels: ${JSON.stringify(copySourcePRLabels)}, must be boolean or array`,
+      );
+    });
 
     return labels;
   });

src/options/ConfigOptions.ts

@@ -31,7 +31,7 @@ type Options = Partial<{
   cherrypickRef: boolean;
   commitConflicts: boolean;
   commitPaths: string[];
-  copySourcePRLabels: boolean;
+  copySourcePRLabels: boolean | string[];
   copySourcePRReviewers: boolean;
   details: boolean;
   dir: string;

src/options/cliArgs.test.ts

@@ -261,6 +261,36 @@ describe('getOptionsFromCliArgs', () => {
     });
   });
 
+  describe('copySourcePRReviewers', () => {
+    it('should be undefined when not provided', () => {
+      const res = getOptionsFromCliArgs([]);
+      expect(res.copySourcePRReviewers).toBe(undefined);
+    });
+
+    it('should be true when option is provided with no value given', () => {
+      const res = getOptionsFromCliArgs(['--copy-source-pr-reviewers']);
+      expect(res.copySourcePRReviewers).toBe(true);
+    });
+
+    it('should set to false', () => {
+      const argv = ['--copy-source-pr-reviewers', 'false'];
+      const res = getOptionsFromCliArgs(argv);
+      expect(res.copySourcePRReviewers).toBe(false);
+    });
+
+    it('should set to true', () => {
+      const argv = ['--copy-source-pr-reviewers', 'true'];
+      const res = getOptionsFromCliArgs(argv);
+      expect(res.copySourcePRReviewers).toBe(true);
+    });
+
+    it('should accept a list of regexes', () => {
+      const argv = ['--copy-source-pr-reviewers', '^foo, bar$, baz*'];
+      const res = getOptionsFromCliArgs(argv);
+      expect(res.copySourcePRReviewers).toEqual(['^foo', 'bar$', 'baz*']);
+    });
+  });
+
   describe('repo', () => {
     it('splits into repoOwner and repoName', () => {
       const argv = ['--repo', 'elastic/kibana'];

src/options/cliArgs.ts

@@ -392,7 +392,13 @@ export function getOptionsFromCliArgs(processArgs: readonly string[]) {
     .option('copySourcePRReviewers', {
       description: 'Copy reviewers from the source PR to the target PR',
       alias: ['copySourcePrReviewers', 'addOriginalReviewers'],
-      type: 'boolean',
+      type: 'string',
+      coerce: (val: string) => {
+        if (val === 'true' || val === '') return true;
+        if (val === 'false') return false;
+
+        return val.split(',').map((s) => s.trim());
+      },
     })
 
     .option('targetBranch', {

src/test/e2e/cli/entrypoint.cli.private.test.ts

@@ -120,7 +120,7 @@ Options:
                                                                                            [boolean]
       --copySourcePRReviewers,                        Copy reviewers from the source PR to the
       --copySourcePrReviewers,                        target PR
-      --addOriginalReviewers                                                               [boolean]
+      --addOriginalReviewers                                                                [string]
   -b, --targetBranch, --branch                        Branch(es) to backport to              [array]
       --targetBranchChoice                            List branches to backport to           [array]
   -l, --targetPRLabel, --label                        Add labels to the target (backport) PR [array]