From 3d7d34aeb2bc27dc386dc5ace6d5600c5ac1d67a Mon Sep 17 00:00:00 2001
From: RoomWithOutRoof <166608075+Jah-yee@users.noreply.github.com>
Date: Fri, 1 May 2026 19:14:30 +0800
Subject: [PATCH] fix & test: throw error on zero-indentation block scalar
 (close #280) (#746)

---
 lib/loader.js       | 7 +++++++
 test/issues/0144.js | 4 ++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/loader.js b/lib/loader.js
index 25abc808..692b1d3d 100644
--- a/lib/loader.js
+++ b/lib/loader.js
@@ -902,6 +902,13 @@ function readBlockScalar(state, nodeIndent) {
       continue;
     }
 
+    // Zero-indentation block scalar is not allowed.
+    // If textIndent is still 0 at this point, it means no explicit indentation
+    // indicator was given and no indentation was detected in content lines.
+    if (!detectedIndent && textIndent === 0) {
+      throwError(state, 'missing indentation for block scalar');
+    }
+
     // End of the scalar.
     if (state.lineIndent < textIndent) {
 
diff --git a/test/issues/0144.js b/test/issues/0144.js
index 4abfb6a9..1abc90c9 100644
--- a/test/issues/0144.js
+++ b/test/issues/0144.js
@@ -1,10 +1,10 @@
 'use strict';
 
-
 var assert = require('assert');
 var yaml   = require('../../');
 
 
 it('Infinite loop when attempting to parse multi-line scalar document that is not indented', function () {
-  assert.strictEqual(yaml.load('--- |\nfoo\n'), 'foo\n');
+  // Block scalar with zero indentation should throw an error (issue #280)
+  assert.throws(() => yaml.load('--- |\nfoo\n'), /missing indentation for block scalar/);
 });