fix: Allow validation to pass when subjectPatternError is provided

src/validatePrTitle.js

@@ -64,27 +64,29 @@ module.exports = async function validatePrTitle(
     );
   }
 
-  if (subjectPattern) {
-    const match = result.subject.match(new RegExp(subjectPattern));
-
+  function throwSubjectPatternError(message) {
     if (subjectPatternError) {
-      throw new Error(
-        formatMessage(subjectPatternError, {
-          subject: result.subject,
-          title: prTitle
-        })
-      );
+      message = formatMessage(subjectPatternError, {
+        subject: result.subject,
+        title: prTitle
+      });
     }
 
+    throw new Error(message);
+  }
+
+  if (subjectPattern) {
+    const match = result.subject.match(new RegExp(subjectPattern));
+
     if (!match) {
-      throw new Error(
+      throwSubjectPatternError(
         `The subject "${result.subject}" found in pull request title "${prTitle}" doesn't match the configured pattern "${subjectPattern}".`
       );
     }
 
     const matchedPart = match[0];
     if (matchedPart.length !== result.subject.length) {
-      throw new Error(
+      throwSubjectPatternError(
         `The subject "${result.subject}" found in pull request title "${prTitle}" isn't an exact match for the configured pattern "${subjectPattern}". Please provide a subject that matches the whole pattern exactly.`
       );
     }

src/validatePrTitle.test.js

@@ -108,6 +108,14 @@ describe('description validation', () => {
     await validatePrTitle('fix: sK!"§4123');
   });
 
+  it('can pass the validation when `subjectPatternError` is configured', async () => {
+    await validatePrTitle('fix: foobar', {
+      subjectPattern: '^(?![A-Z]).+$',
+      subjectPatternError:
+        'The subject found in the pull request title cannot start with an uppercase character.'
+    });
+  });
+
   it('uses the `subjectPatternError` if available when the `subjectPattern` does not match', async () => {
     const customError =
       'The subject found in the pull request title cannot start with an uppercase character.';