fix(validation): change header max length to 72

the previous spec was wrong the expectation was the maximum length was of 100
but its actually 72 which has now been updated and put on a variable for easier
access case it changes in the future

src/lib/validation/validateSubject.spec.ts

@@ -1,4 +1,4 @@
-import validateSubject from './validateSubject';
+import validateSubject, { MAXIMUM_LENGTH } from './validateSubject';
 
 describe('#validateSubject', () => {
   it('prevents commits if no subject specified', () => {
@@ -16,7 +16,7 @@ describe('#validateSubject', () => {
     ).toContain('first word must be lowercase');
   });
 
-  it('prevents commits if header is greater than 100 characters', () => {
+  it(`prevents commits if header is greater than ${MAXIMUM_LENGTH} characters`, () => {
     expect(
       validateSubject(
         'lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut',

src/lib/validation/validateSubject.ts

@@ -1,5 +1,7 @@
 import validateLowercase from './validateLowercase';
 
+export const MAXIMUM_LENGTH = 72;
+
 export default (input: string, answers: any) => {
   if (!input || input === '') {
     return 'Must specify subject';
@@ -15,9 +17,10 @@ export default (input: string, answers: any) => {
 
   const inputSize = input.length;
 
-  if (typeSize + scopeSize + inputSize <= 100) {
+  if (typeSize + scopeSize + inputSize <= MAXIMUM_LENGTH) {
     return true;
   }
 
-  return `Subject should be ${100 - (typeSize + scopeSize)} characters or less`;
+  return `Subject should be ${MAXIMUM_LENGTH -
+    (typeSize + scopeSize)} characters or less`;
 };