Support multiline snapshot labels

Fixes #2769.

Co-authored-by: Mark Wubben <[email protected]>

Author: KillyMXI

lib/snapshot-manager.js

@@ -93,7 +93,9 @@ function formatEntry(snapshot, index) {
 		concordance.formatDescriptor(concordance.deserialize(data), concordanceOptions) :
 		'<No Data>';
 
-	return `> ${label}\n\n${indentString(description, 4)}`;
+	const blockquote = label.split(/\n/).map(line => '> ' + line).join('\n');
+
+	return `${blockquote}\n\n${indentString(description, 4)}`;
 }
 
 function combineEntries({blocks}) {

test/snapshot-tests/fixtures/multiline-snapshot-label/package.json

@@ -0,0 +1 @@
+{}

test/snapshot-tests/fixtures/multiline-snapshot-label/test.js

@@ -0,0 +1,14 @@
+const test = require(process.env.TEST_AVA_IMPORT_FROM);
+
+const f = () => {
+	return [
+		'Hello',
+		'World!'
+	].join(', ');
+};
+
+test('snapshot with a multiline label', t => {
+	const result = f();
+	const label = '```javascript\n' + f.toString() + '\n```';
+	t.snapshot(result, label);
+});

test/snapshot-tests/formatting.js

@@ -0,0 +1,24 @@
+import fs from 'fs';
+import path from 'path';
+
+import test from '@ava/test';
+
+import {cwd, fixture} from '../helpers/exec.js';
+import {withTemporaryFixture} from '../helpers/with-temporary-fixture.js';
+
+test('multiline snapshot label should be formatted correctly in the report', async t => {
+	await withTemporaryFixture(cwd('multiline-snapshot-label'), async cwd => {
+		// Run test fixture
+		await fixture(['--update-snapshots'], {
+			cwd,
+			env: {
+				AVA_FORCE_CI: 'not-ci'
+			}
+		});
+
+		// Assert report is unchanged
+		const reportPath = path.join(cwd, 'test.js.md');
+		const report = fs.readFileSync(reportPath, {encoding: 'utf8'});
+		t.snapshot(report, 'resulting snapshot report');
+	});
+});

test/snapshot-tests/snapshots/formatting.js.md

@@ -0,0 +1,29 @@
+# Snapshot report for `test/snapshot-tests/formatting.js`
+
+The actual snapshot is saved in `formatting.js.snap`.
+
+Generated by [AVA](https://avajs.dev).
+
+## multiline snapshot label should be formatted correctly in the report
+
+> resulting snapshot report
+
+    `# Snapshot report for \`test.js\`␊
+    ␊
+    The actual snapshot is saved in \`test.js.snap\`.␊
+    ␊
+    Generated by [AVA](https://avajs.dev).␊
+    ␊
+    ## snapshot with a multiline label␊
+    ␊
+    > \`\`\`javascript␊
+    > () => {␊
+    > 	return [␊
+    > 		'Hello',␊
+    > 		'World!'␊
+    > 	].join(', ');␊
+    > }␊
+    > \`\`\`␊
+    ␊
+        'Hello, World!'␊
+    `