feat: added templates

README.md

@@ -52,8 +52,14 @@ jobs:
           # This example ensures the subject doesn't start with an uppercase character.
           subjectPattern: ^(?![A-Z]).+$
           # Configure custom error message that should be passed to the logs to better describe the error thrown by subject pattern validation.
+          # You can pass template values to the error test
+          # - ${subject} will be replaced with the subject of the PR title
+          # - ${title} will be replaced with the PR title
+          # This example will return the following error of PR title "fix(core): Test": 
+          #     The subject "Test" found in the pull request title "fix(core): Test" didn't match the configured pattern.
+          #     Please ensure that the subject doesn't start with an uppercase character.
           subjectPatternError: |
-            The subject found in the pull request title didn't match the configured pattern.
+            The subject "${subject}" found in the pull request title "${title}" didn't match the configured pattern.
             Please ensure that the subject doesn't start with an uppercase character.
           # For work-in-progress PRs you can typically use draft pull requests 
           # from Github. However, private repositories on the free plan don't have 

src/SubjectPatternErrorParser.js

@@ -0,0 +1,2 @@
+module.exports = (subjectPatternError, subject, title) =>
+  subjectPatternError.replace('${subject}', subject).replace('${title}', title);

src/SubjectPatternErrorParser.test.js

@@ -0,0 +1,24 @@
+const subjectPatternErrorParser = require('./SubjectPatternErrorParser');
+
+describe('parse pattern error', () => {
+  it('parse string without changes if template values not provided', () => {
+    const customError = 'this is test';
+    expect(subjectPatternErrorParser(customError)).toEqual(customError);
+  });
+
+  it('parses string properly by replacing one template value', () => {
+    expect(
+      subjectPatternErrorParser('this is ${subject} test', 'my subject')
+    ).toEqual('this is my subject test');
+  });
+
+  it('parses string properly by replacing both template values', () => {
+    expect(
+      subjectPatternErrorParser(
+        'this ${title} is ${subject} test',
+        'my subject',
+        'my title'
+      )
+    ).toEqual('this my title is my subject test');
+  });
+});

src/validatePrTitle.js

@@ -1,6 +1,7 @@
 const conventionalCommitsConfig = require('conventional-changelog-conventionalcommits');
 const conventionalCommitTypes = require('conventional-commit-types');
 const parser = require('conventional-commits-parser').sync;
+const subjectPatternErrorParser = require('./SubjectPatternErrorParser');
 
 const defaultTypes = Object.keys(conventionalCommitTypes.types);
 
@@ -66,7 +67,11 @@ module.exports = async function validatePrTitle(
   if (subjectPattern) {
     const match = result.subject.match(new RegExp(subjectPattern));
 
-    if (subjectPatternError) throw new Error(subjectPatternError);
+    if (subjectPatternError) {
+      throw new Error(
+        subjectPatternErrorParser(subjectPatternError, result.subject, prTitle)
+      );
+    }
 
     if (!match) {
       throw new Error(

src/validatePrTitle.test.js

@@ -118,6 +118,18 @@ describe('description validation', () => {
     ).rejects.toThrow(customError);
   });
 
+  it('throws custom error enriched with template values', async () => {
+    await expect(
+      validatePrTitle('fix: Foobar', {
+        subjectPattern: '^(?![A-Z]).+$',
+        subjectPatternError:
+          'The subject "${subject}" found in the pull request title "${title}" cannot start with an uppercase character.'
+      })
+    ).rejects.toThrow(
+      'The subject "Foobar" found in the pull request title "fix: Foobar" cannot start with an uppercase character.'
+    );
+  });
+
   it('throws for invalid subjects', async () => {
     await expect(
       validatePrTitle('fix: Foobar', {