List TemplateContext value names (#380)

Fluid.Tests/TemplateContextTests.cs

@@ -110,6 +110,20 @@ public void SegmentAccessorCacheShouldVaryByType()
             Assert.Equal("model1", template.Render(new TemplateContext(model1, options)));
         }
 
+        [Fact]
+        public void CaptureShouldUpdateContext()
+        {
+            _parser.TryParse("{% capture greetings %}Hello {{text1}}{%endcapture%}", out var template, out var error);
+
+            var context = new TemplateContext();
+            context.SetValue("text1", "World");
+
+            template.Render(context);
+
+            Assert.Equal("Hello World", context.GetValue("greetings").ToStringValue());
+            Assert.Contains("greetings", context.ValueNames);
+        }
+
         private class TestClass
         {
             public string Name { get; set; }

Fluid/TemplateContext.cs

@@ -150,11 +150,26 @@ public void ReleaseScope()
             }
         }
 
+        /// <summary>
+        /// Gets the names of the values.
+        /// </summary>
+        public IEnumerable<string> ValueNames => LocalScope.Properties;
+
+        /// <summary>
+        /// Gets a value from the context.
+        /// </summary>
+        /// <param name="name">The name of the value.</param>
         public FluidValue GetValue(string name)
         {
             return LocalScope.GetValue(name);
         }
 
+        /// <summary>
+        /// Sets a value on the context.
+        /// </summary>
+        /// <param name="name">The name of the value.</param>
+        /// <param name="value">Teh value to set.</param>
+        /// <returns></returns>
         public TemplateContext SetValue(string name, FluidValue value)
         {
             LocalScope.SetValue(name, value);