diff --git a/Upsilon/StandardLibraries/Global.cs b/Upsilon/StandardLibraries/BasicFunctions.cs
similarity index 100%
rename from Upsilon/StandardLibraries/Global.cs
rename to Upsilon/StandardLibraries/BasicFunctions.cs
diff --git a/UpsilonTests/StandardLibraryTests/BasicFunctionsTests.cs b/UpsilonTests/StandardLibraryTests/BasicFunctionsTests.cs
index 4cc9055..f3647e7 100644
--- a/UpsilonTests/StandardLibraryTests/BasicFunctionsTests.cs
+++ b/UpsilonTests/StandardLibraryTests/BasicFunctionsTests.cs
@@ -1,3 +1,4 @@
+using System;
 using Upsilon.Evaluator;
 using Xunit;
 
@@ -10,9 +11,18 @@ namespace UpsilonTests.StandardLibraryTests
         }
 
         [Fact]
-        public void Assert()
+        public void AssertTest()
         {
             new Script("assert(true)", BoundScope, StaticScope).Evaluate();
+            Assert.Throws<Exception>(() => new Script("assert(false)", BoundScope, StaticScope).Evaluate());
+        }
+
+        [Fact]
+        public void Error()
+        {
+            var e = Assert.Throws<Exception>(() =>
+                new Script(@"error(""test_error"")", BoundScope, StaticScope).Evaluate());
+            Assert.Equal("test_error", e.Message);
         }
 
     }
diff --git a/UpsilonTests/TestClass.cs b/UpsilonTests/TestClass.cs
index 3993b5e..bf1e22f 100644
--- a/UpsilonTests/TestClass.cs
+++ b/UpsilonTests/TestClass.cs
@@ -1,8 +1,5 @@
-using System.Collections.Generic;
-using Upsilon.BaseTypes;
 using Upsilon.Binder;
 using Upsilon.Evaluator;
-using Upsilon.StandardLibraries;
 using Xunit;
 
 namespace UpsilonTests
@@ -10,10 +7,10 @@ namespace UpsilonTests
     [Collection("collection")]
     public abstract class TestClass
     {
-        public EvaluationScope StaticScope { get; }
-        public BoundScope BoundScope  { get; }
+        protected EvaluationScope StaticScope { get; }
+        protected BoundScope BoundScope  { get; }
 
-        public TestClass(StaticScriptFixture fix)
+        protected TestClass(StaticScriptFixture fix)
         {
             StaticScope = fix.StaticScope;
             BoundScope = fix.BoundScope;