fix: sanitize ensure.case #211 (#217)

Author: marionebl

@commitlint/ensure/src/case.js

@@ -24,11 +24,13 @@ function ensureCase(raw = '', target = 'lowercase') {
 		case 'uppercase':
 			return input.toUpperCase() === input;
 		case 'sentence-case':
-		case 'sentencecase':
+		case 'sentencecase': {
+			const word = input.split(' ')[0];
 			return (
-				ensureCase(raw.charAt(0), 'upper-case') &&
-				ensureCase(raw.substring(1), 'lower-case')
+				ensureCase(word.charAt(0), 'upper-case') &&
+				ensureCase(word.slice(1), 'lower-case')
 			);
+		}
 		case 'lower-case':
 		case 'lowercase':
 		case 'lowerCase': // Backwards compat config-angular v4

@commitlint/ensure/src/case.test.js

@@ -54,8 +54,8 @@ test('false for UPPERCASE on sentencecase', t => {
 	t.is(ensure('UPPERCASE', 'sentence-case'), false);
 });
 
-test('false for Start Case on sentencecase', t => {
-	t.is(ensure('Start Case', 'sentence-case'), false);
+test('true for Start Case on sentencecase', t => {
+	t.is(ensure('Start Case', 'sentence-case'), true);
 });
 
 test('false for PascalCase on sentencecase', t => {