refactor(core): reuse ensureCase internally

@commitlint/core/src/library/ensure-case.js

@@ -1,10 +1,8 @@
 import {camelCase, kebabCase, snakeCase, upperFirst, startCase} from 'lodash';
 
-function capitalizeFirstLetter(string) {
-    return string.charAt(0).toUpperCase() + string.slice(1);
-}
+export default ensureCase;
 
-export default (raw = '', target = 'lowercase') => {
+function ensureCase(raw = '', target = 'lowercase') {
 	const input = String(raw);
 
 	switch (target) {
@@ -23,10 +21,14 @@ export default (raw = '', target = 'lowercase') => {
 			return input.toUpperCase() === input;
 		case 'sentence-case':
 		case 'sentencecase':
-			return capitalizeFirstLetter(input.toLowerCase()) === input;
+			return (
+				ensureCase(raw.charAt(0), 'upper-case') &&
+				ensureCase(raw.substring(1), 'lower-case')
+			);
 		case 'lower-case':
 		case 'lowercase':
-		default:
 			return input.toLowerCase() === input;
+		default:
+			throw new TypeError(`ensure-case: Unknown target case "${target}"`);
 	}
-};
+}

@commitlint/core/src/library/ensure-case.test.js

@@ -42,17 +42,34 @@ test('false for lowercase on lowercase', t => {
 });
 
 test('true for sentencecase on sentencecase', t => {
-	const actual = ensure('Sentence case', 'sentencecase');
+	const actual = ensure('Sentence case', 'sentence-case');
 	t.is(actual, true);
 });
 
-test('false for sentencecase on sentencecase', t => {
-    const testCase = 'sentencecase';
-	t.is(ensure('sentence case', testCase), false);
-	t.is(ensure('SENTENCE CASE', testCase), false);
-	t.is(ensure('Sentence Case', testCase), false);
-	t.is(ensure('sentence-case', testCase), false);
-	t.is(ensure('SentenceCase', testCase), false);
-	t.is(ensure('sentence_case', testCase), false);
-	t.is(ensure('sentenceCase', testCase), false);
+test('false for lowsercase on sentencecase', t => {
+	t.is(ensure('sentence case', 'sentence-case'), false);
+});
+
+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('false for PascalCase on sentencecase', t => {
+	t.is(ensure('PascalCase', 'sentence-case'), false);
+});
+
+test('false for kebab-case on sentencecase', t => {
+	t.is(ensure('kebab-case', 'sentence-case'), false);
+});
+
+test('false for snake_case on sentencecase', t => {
+	t.is(ensure('snake_case', 'sentence-case'), false);
+});
+
+test('false for camelCase on sentencecase', t => {
+	t.is(ensure('camelCase', 'sentence-case'), false);
 });

@commitlint/core/src/rules/scope-case.test.js

@@ -159,11 +159,7 @@ test('with kebabcase scope should fail for "always pascalcase"', async t => {
 });
 
 test('with kebabcase scope should succeed for "always kebabcase"', async t => {
-	const [actual] = scopeCase(
-		await parsed.kebabcase,
-		'always',
-		'kebabcase-case'
-	);
+	const [actual] = scopeCase(await parsed.kebabcase, 'always', 'kebab-case');
 	const expected = true;
 	t.is(actual, expected);
 });