Handle if else statements

UpsilonTests/IfTests.cs

@@ -1,3 +1,4 @@
+using Upsilon.BaseTypes.Number;
 using Upsilon.Evaluator;
 using Xunit;
 
@@ -8,11 +9,30 @@ namespace UpsilonTests
         [Fact]
         public void BasicIfTest()
         {
-            var input = "if true then val = true end";
+            var input  = "if true then val = true end";
             var script = new Script(input);
             Assert.Empty(script.Diagnostics.Messages);
             var actual = script.Evaluate<bool>();
             Assert.True(actual);
         }
+
+        [Theory]
+        [InlineData("true", 3, 8, 3)]
+        [InlineData("false", 3, 8, 8)]
+        [InlineData("5 == 5", 500, 349, 500)]
+        public void BasicIfElseTests(string condition, int in1, int in2, long expected)
+        {
+            var input  =
+$@"
+if {condition} then
+    val = {in1}
+else
+    val = {in2}
+end";
+            var script = new Script(input);
+            Assert.Empty(script.Diagnostics.Messages);
+            var actual = (long)(NumberLong)script.Evaluate();
+            Assert.Equal(expected, actual);
+        }
     }
 }