add: Array declaration and variable indexer.

CanonSharp.Tests/Utils/LexicalTestBase.cs

@@ -24,13 +24,15 @@ public abstract class LexicalTestBase
     }
 
     protected static void ValidateLexicalTokens(IParser<char, IEnumerable<LexicalToken>> parser, string input,
-        IEnumerable<(LexicalTokenType, string)> exceptedResult)
+        List<(LexicalTokenType, string)> exceptedResult)
     {
         StringReadState state = new(input);
         IParseResult<char, IEnumerable<LexicalToken>> result = parser.Parse(state);
+        List<LexicalToken> actualResult = result.Value.ToList();
 
+        Assert.Equal(exceptedResult.Count, actualResult.Count);
         foreach (((LexicalTokenType exceptedType, string exceptedValue), LexicalToken token) in exceptedResult.Zip(
-                     result.Value))
+                     actualResult))
         {
             Assert.Equal(exceptedType, token.TokenType);
             Assert.Equal(exceptedValue, token.LiteralValue);