From 1deed358ac5efe2a3aa5007bd9eefa36f9313e24 Mon Sep 17 00:00:00 2001
From: vasiliy-mikhailov <vasiliy-mikhailov@users.noreply.github.com>
Date: Mon, 22 Jun 2026 21:58:07 +0300
Subject: [PATCH] Add unit tests for ExpressionBuilder

Additive unit tests only - no existing test or production code changed.
---
 .../org/petitparser/tools/ExpressionBuilderTest.java  | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/petitparser-core/src/test/java/org/petitparser/tools/ExpressionBuilderTest.java b/petitparser-core/src/test/java/org/petitparser/tools/ExpressionBuilderTest.java
index 331e3d8..fcbc403 100644
--- a/petitparser-core/src/test/java/org/petitparser/tools/ExpressionBuilderTest.java
+++ b/petitparser-core/src/test/java/org/petitparser/tools/ExpressionBuilderTest.java
@@ -2,12 +2,15 @@
 
 import org.junit.Before;
 import org.junit.Test;
+import org.petitparser.context.Result;
 import org.petitparser.parser.Parser;
 
 import java.util.List;
 
 import static java.util.Arrays.asList;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
 import static org.petitparser.parser.primitive.CharacterParser.digit;
 import static org.petitparser.parser.primitive.CharacterParser.of;
 import static org.petitparser.parser.primitive.StringParser.of;
@@ -313,4 +316,12 @@ public void testEvaluatePrefixNegate() {
     assertEvaluation("--1", 1);
     assertEvaluation("---1", -1);
   }
+
+  @Test
+  public void testBuildWithoutGroupsFails() {
+    Parser parser = new ExpressionBuilder().build();
+    assertNotNull(parser);
+    Result result = parser.parse("");
+    assertTrue(result.isFailure());
+  }
 }