fix(commit): the bang (!) indicates a breaking change

A commit is considered a breaking (major) change when a bang  char is
encountered prior to the colon + subject and no prior commit notes are
found.

Ref: gh-5

index.js

@@ -2,6 +2,7 @@
 
 const templates = require('./lib/templates/index.js')
 const commit = require('./lib/commit.js')
+const constants = require('./lib/constants.js')
 const now = new Date()
 const year = now.getFullYear()
 const day = String(now.getDate()).padStart(2, '0')
@@ -13,6 +14,7 @@ module.exports = {
 , parserOpts: {
     noteKeywords: ['BREAKING CHANGES', 'BREAKING CHANGE', 'BREAKING']
   , headerPattern: /^(\w*)(?:\((.*)\))?!?: (.*)$/
+  , breakingHeaderPattern: constants.BREAKING_HEADER_REGEX
   , headerCorrespondence: ['type', 'scope', 'subject']
   , issuePrefixes: ['#', 'gh-']
   , referenceActions: [

lib/commit.js

@@ -28,6 +28,7 @@ function typeOf(type) {
 function transform(commit) {
   commit.type = typeOf(commit.type)
   commit.shortHash = commit.hash.substring(0, 7)
+
   for (const note of commit.notes) {
     note.title = '**BREAKING CHANGES**'
   }

lib/constants.js

@@ -0,0 +1,5 @@
+'use strict'
+
+module.exports = {
+  BREAKING_HEADER_REGEX: /^(\w*)(?:\((.*)\))?!: (.*)$/
+}

package.json

@@ -54,6 +54,13 @@
     "extends": "logdna",
     "parserOptions": {
       "ecmaVersion": 2019
+    },
+    "rules": {
+      "no-unused-vars": [2, {
+        "vars": "all",
+        "args": "none",
+        "varsIgnorePattern": "^_$"
+      }]
     }
   },
   "tap": {

test/unit/commit/transform.js

@@ -9,13 +9,14 @@ test('commit#transform', async (t) => {
       'long': 'c644dd5aa62fa579bef2d793b6bc9d711f308a9b'
     , 'short': 'c644dd5'
     }
+  , notes: [{
+      title: '**BREAKING CHANGES**'
+    , text: 'This will break things'
+    }]
   , hash: 'c644dd5aa62fa579bef2d793b6bc9d711f308a9b'
   , type: 'feat'
   , scope: 'core'
-  , notes: [{
-      title: 'Does not matter'
-    , text: 'BREAKING CHANGE: This will break things'
-    }]
+  , header: 'feat(core): this is a simple commit'
   , references: [{
       issue: '1000'
     , raw: 'Ref: gh-1000'

test/unit/config.js

@@ -2,6 +2,7 @@
 
 const {test, threw} = require('tap')
 const config = require('../../index.js')
+const constants = require('../../lib/constants.js')
 
 function sortByType(a, b) {
   return a.type < b.type ? -1 : 1
@@ -16,6 +17,7 @@ test('semantic-release-config-logdna', async (t) => {
   t.match(config.parserOpts, {
     noteKeywords: ['BREAKING CHANGES', 'BREAKING CHANGE', 'BREAKING']
   , headerPattern: /^(\w*)(?:\((.*)\))?!?: (.*)$/
+  , breakingHeaderPattern: constants.BREAKING_HEADER_REGEX
   , headerCorrespondence: ['type', 'scope', 'subject']
   , issuePrefixes: ['#', 'gh-']
   , referenceActions: [

test/unit/constants.js

@@ -0,0 +1,34 @@
+'use strict'
+
+const {test, threw} = require('tap')
+const constants = require('../../lib/constants.js')
+
+test('constants', async (t) => {
+  t.strictEqual(Object.keys(constants).length, 1, 'expected number of constants')
+
+  t.match(constants, {
+    BREAKING_HEADER_REGEX: RegExp
+  })
+
+  t.test('BREAKING_HEADER_REGEX', async (t) => {
+    const {BREAKING_HEADER_REGEX} = constants
+    t.test('breaking change w/o scope', async (t) => {
+      const match = BREAKING_HEADER_REGEX.exec('test!: this is breaking')
+      const [_, type, scope, subject] = match
+      t.strictEqual(type, 'test', 'commit type')
+      t.strictEqual(scope, undefined, 'commit scope')
+      t.strictEqual(subject, 'this is breaking', 'commit subject')
+    })
+    t.test('breaking change w/ scope', async (t) => {
+      const match = BREAKING_HEADER_REGEX.exec('doc(readme)!: this is breaking')
+      const [_, type, scope, subject] = match
+      t.strictEqual(type, 'doc', 'commit type')
+      t.strictEqual(scope, 'readme', 'commit scope')
+      t.strictEqual(subject, 'this is breaking', 'commit subject')
+    })
+    t.test('non-breaking change', async (t) => {
+      const match = BREAKING_HEADER_REGEX.exec('doc(readme): this is breaking')
+      t.notOk(match, 'no match found')
+    })
+  })
+}).catch(threw)