From abadaf4d5d9db5fc0c476de51037bd7fadda678d Mon Sep 17 00:00:00 2001
From: Futago-za Ryuu <futagoza.ryuu@gmail.com>
Date: Fri, 20 Oct 2017 19:01:19 +0100
Subject: [PATCH] Add test for empty grammars

This add's a test that ensures grammars without any rules are not accepted.
---
 test/spec/unit/parser.spec.js | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/test/spec/unit/parser.spec.js b/test/spec/unit/parser.spec.js
index c794c5f..f4a749c 100644
--- a/test/spec/unit/parser.spec.js
+++ b/test/spec/unit/parser.spec.js
@@ -226,6 +226,20 @@ describe("PEG.js grammar parser", function() {
     chai.use(helpers);
   });
 
+  // Grammars without any rules are not accepted.
+  it("parses Rule+", function() {
+    expect("start = a").to.parseAs(ruleRefGrammar("a"));
+    let grammar = ruleRefGrammar("a");
+    grammar.initializer = {
+      "type": "initializer",
+      "code": ""
+    };
+    expect("{}\nstart = a").to.parseAs(grammar);
+
+    expect("").to.failToParse();
+    expect("{}").to.failToParse();
+  });
+
   // Canonical Grammar is "a = 'abcd'; b = 'efgh'; c = 'ijkl';".
   it("parses Grammar", function() {
     expect("\na = 'abcd';\n").to.parseAs(