refactor(core): unify line splitting

Author: marionebl

Diff for: @commitlint/core/src/library/to-lines.js

@@ -0,0 +1,7 @@
+export default function toLines(input) {
+	if (typeof input === 'undefined') {
+		return [];
+	}
+
+	return input.split(/(?:\r?\n)/);
+}

Diff for: @commitlint/core/src/library/to-lines.test.js

@@ -0,0 +1,18 @@
+import test from 'ava';
+import toLines from './to-lines';
+
+test('should return an array for empty input', t => {
+	t.deepEqual(toLines(), []);
+});
+
+test('should return an array for empty string input', t => {
+	t.deepEqual(toLines(''), ['']);
+});
+
+test('should split LF newlines', t => {
+	t.deepEqual(toLines('some\nweird\ntext'), ['some', 'weird', 'text']);
+});
+
+test('should split CR+LF newlines', t => {
+	t.deepEqual(toLines('some\r\nweird\r\ntext'), ['some', 'weird', 'text']);
+});

Diff for: @commitlint/core/src/rules/body-leading-blank.js

@@ -1,14 +1,13 @@
+import toLines from '../library/to-lines';
+
 export default (parsed, when) => {
 	// Flunk if no body is found
 	if (!parsed.body) {
 		return [true];
 	}
 
 	const negated = when === 'never';
-
-	// Get complete body split into lines
-	const lines = (parsed.raw || '').split(/\r|\n/).slice(1);
-	const [leading] = lines;
+	const [leading] = toLines(parsed.raw).slice(1);
 
 	// Check if the first line of body is empty
 	const succeeds = leading === '';

Diff for: @commitlint/core/src/rules/footer-leading-blank.js

@@ -1,17 +1,13 @@
+import toLines from '../library/to-lines';
+
 export default (parsed, when) => {
 	// Flunk if no footer is found
 	if (!parsed.footer) {
 		return [true];
 	}
 
 	const negated = when === 'never';
-
-	const count = (parsed.body || '').split(/\r|\n/).length;
-
-	// Get complete message split into lines
-	const lines = (parsed.raw || '').split(/\r|\n/).slice(count + 1);
-
-	const [leading] = lines;
+	const [leading] = toLines(parsed.raw).slice(toLines(parsed.body).length + 1);
 
 	// Check if the first line of footer is empty
 	const succeeds = leading === '';

Diff for: @commitlint/core/src/rules/signed-off-by.js

@@ -1,8 +1,11 @@
+import toLines from '../library/to-lines';
+
 export default (parsed, when, value) => {
-	const input = /.*\n(Signed-off-by:).*\n+/g.exec(parsed.raw);
+	const lines = toLines(parsed.raw).filter(Boolean);
+	const last = lines[lines.length - 1];
 
 	const negated = when === 'never';
-	const hasSignedOffBy = Boolean(input && input[1] === value);
+	const hasSignedOffBy = last.startsWith(value);
 
 	return [
 		negated ? !hasSignedOffBy : hasSignedOffBy,