fix: support includeZero=true on #if helper (issue #285)

source/Handlebars.Test/Issues/Issue285Tests.cs

@@ -0,0 +1,104 @@
+using Xunit;
+
+namespace HandlebarsDotNet.Test.Issues
+{
+    /// <summary>
+    /// Regression tests for GitHub issue #285:
+    /// Support the <c>includeZero=true</c> hash argument on the built-in <c>#if</c> helper,
+    /// matching Handlebars.js behaviour (https://handlebarsjs.com/guide/builtin-helpers.html#if).
+    /// </summary>
+    public class Issue285Tests
+    {
+        [Fact]
+        public void IfWithIncludeZeroTrue_ZeroInt_RendersBlock()
+        {
+            var source = "{{#if value includeZero=true}}yes{{else}}no{{/if}}";
+            var template = Handlebars.Compile(source);
+            var result = template(new { value = 0 });
+            Assert.Equal("yes", result);
+        }
+
+        [Fact]
+        public void IfWithIncludeZeroTrue_ZeroDouble_RendersBlock()
+        {
+            var source = "{{#if value includeZero=true}}yes{{else}}no{{/if}}";
+            var template = Handlebars.Compile(source);
+            var result = template(new { value = 0.0 });
+            Assert.Equal("yes", result);
+        }
+
+        [Fact]
+        public void IfWithIncludeZeroTrue_NonZeroInt_RendersBlock()
+        {
+            var source = "{{#if value includeZero=true}}yes{{else}}no{{/if}}";
+            var template = Handlebars.Compile(source);
+            var result = template(new { value = 1 });
+            Assert.Equal("yes", result);
+        }
+
+        [Fact]
+        public void IfWithIncludeZeroFalse_ZeroInt_DoesNotRenderBlock()
+        {
+            var source = "{{#if value includeZero=false}}yes{{else}}no{{/if}}";
+            var template = Handlebars.Compile(source);
+            var result = template(new { value = 0 });
+            Assert.Equal("no", result);
+        }
+
+        [Fact]
+        public void IfWithoutIncludeZero_ZeroInt_StillTreatedAsFalsy()
+        {
+            var source = "{{#if value}}yes{{else}}no{{/if}}";
+            var template = Handlebars.Compile(source);
+            var result = template(new { value = 0 });
+            Assert.Equal("no", result);
+        }
+
+        [Fact]
+        public void IfWithIncludeZeroTrue_NullValue_StillTreatedAsFalsy()
+        {
+            var source = "{{#if value includeZero=true}}yes{{else}}no{{/if}}";
+            var template = Handlebars.Compile(source);
+            var result = template(new { value = (object)null });
+            Assert.Equal("no", result);
+        }
+
+        [Fact]
+        public void IfWithIncludeZeroTrue_EmptyString_StillTreatedAsFalsy()
+        {
+            var source = "{{#if value includeZero=true}}yes{{else}}no{{/if}}";
+            var template = Handlebars.Compile(source);
+            var result = template(new { value = string.Empty });
+            Assert.Equal("no", result);
+        }
+
+        [Fact]
+        public void IfWithIncludeZeroTrue_FalseBool_StillTreatedAsFalsy()
+        {
+            var source = "{{#if value includeZero=true}}yes{{else}}no{{/if}}";
+            var template = Handlebars.Compile(source);
+            var result = template(new { value = false });
+            Assert.Equal("no", result);
+        }
+
+        [Fact]
+        public void IfWithIncludeZeroTrue_TrueBool_RendersBlock()
+        {
+            var source = "{{#if value includeZero=true}}yes{{else}}no{{/if}}";
+            var template = Handlebars.Compile(source);
+            var result = template(new { value = true });
+            Assert.Equal("yes", result);
+        }
+
+        [Fact]
+        public void IfWithHashArgument_DoesNotCrash()
+        {
+            // Regression test: passing any hash arg to #if previously threw
+            // InvalidOperationException: "Sequence contains more than one element".
+            var source = "{{#if value includeZero=true}}yes{{/if}}";
+            var template = Handlebars.Compile(source);
+            var result = template(new { value = 42 });
+            Assert.Equal("yes", result);
+        }
+    }
+}

source/Handlebars/Compiler/Lexer/Converter/BlockAccumulators/ConditionalBlockAccumulatorContext.cs

@@ -8,13 +8,13 @@ namespace HandlebarsDotNet.Compiler
     internal class ConditionalBlockAccumulatorContext : BlockAccumulatorContext
     {
         private enum TestType { Direct, Reverse }
-        
+
         private static readonly HashSet<string> ValidHelperNames = new HashSet<string> { "if", "unless" };
-        
+
         private readonly List<ConditionalExpression> _conditionalBlock = new List<ConditionalExpression>();
         private Expression _currentCondition;
         private List<Expression> _bodyBuffer = new List<Expression>();
-        
+
         public sealed override string BlockName { get; protected set; }
 
         public ConditionalBlockAccumulatorContext(Expression startingNode)

source/Handlebars/Compiler/Translation/Expression/BoolishConverter.cs

@@ -30,7 +30,6 @@ protected override Expression VisitBoolishExpression(BoolishExpression bex)
             var @object = Arg<object>(condition);
             var includeZero = Arg<bool>(hashParameters.Parameters.Count == 1 ? hashParameters.Parameters[IncludeZero] : Expression.Constant(false));
             return Call(() => HandlebarsUtils.IsTruthyOrNonEmpty(@object, includeZero));
-
         }
     }
 }