Adding unit tests for ~ operator

Jint.Tests/Runtime/EngineTests.cs

@@ -93,8 +93,18 @@ namespace Jint.Tests.Runtime
             var result = engine.Execute(source).GetCompletionValue().ToObject();
 
             Assert.Equal(expected, result);
+        }
+
+        [Theory]
+        [InlineData(-59d, "~58")]
+        [InlineData(58d, "~~58")]
+        public void ShouldInterpretUnaryExpression(object expected, string source)
+        {
+            var engine = new Engine();
+            var result = engine.Execute(source).GetCompletionValue().ToObject();
+
+            Assert.Equal(expected, result);
         }
-
         [Fact]
         public void ShouldEvaluateHasOwnProperty()
         {
@@ -556,7 +566,7 @@ namespace Jint.Tests.Runtime
         }
 
         [Theory]
-        [InlineData(true, "'ab' == 'a' + 'b'")]
+        [InlineData(true, "'ab' == 'a' + 'b'")]
         public void OperatorsPrecedence(object expected, string source)
         {
             var engine = new Engine();