Adds Unary length operator

UpsilonTests/GeneralTests/LengthOperatorTests.cs

@@ -0,0 +1,27 @@
+using Upsilon.Binder;
+using Upsilon.Evaluator;
+using Upsilon.StandardLibraries;
+using Xunit;
+
+namespace UpsilonTests.GeneralTests
+{
+    public class LengthOperatorTests : TestClass
+    {
+        public LengthOperatorTests(StaticScriptFixture fix) : base(fix)
+        {
+        }
+
+        [Theory]
+        [InlineData(@"#""test""", 4)]
+        [InlineData(@"#{100,50,60,7863,1564,12354,10354}", 7)]
+        public void Test(string input, long expectedOutput)
+        {
+            var script = new Script(input, BoundScope, StaticScope);
+            Assert.Empty(script.Diagnostics.Messages);
+            var actual = script.Evaluate<long>();
+            Assert.Empty(script.Diagnostics.Messages);
+            Assert.Equal(expectedOutput, actual);
+        }
+
+    }
+}

UpsilonTests/StandardLibraryTests/BasicFunctionsTests.cs

@@ -26,7 +26,7 @@ namespace UpsilonTests.StandardLibraryTests
         }
 
         [Fact]
-        public void IPairsTest()
+        public void UpTillNilPairsTest()
         {
             const string input = @"
 arr = {100, 56, 28, nil, 100}