fix(if): Support resolving all number types 0 or below as false

Sources/Expression.swift

@@ -52,11 +52,7 @@ final class VariableExpression: Expression, CustomStringConvertible {
       truthy = !result.isEmpty
     } else if let result = result as? Bool {
       truthy = result
-    } else if let result = result as? Int {
+    } else if let value = result, let result = toNumber(value: value) {
-      truthy = result > 0
-    } else if let result = result as? Float {
-      truthy = result > 0
-    } else if let result = result as? Double {
       truthy = result > 0
     } else if result != nil {
       truthy = true
@@ -134,3 +130,40 @@ final class AndExpression: Expression, InfixOperator, CustomStringConvertible {
     return try rhs.evaluate(context: context)
   }
 }
+
+
+func toNumber(value: Any) -> Float80? {
+    if let value = value as? Float {
+        return Float80(value)
+    } else if let value = value as? Double {
+        return Float80(value)
+    } else if let value = value as? UInt {
+        return Float80(value)
+    } else if let value = value as? Int {
+        return Float80(value)
+    } else if let value = value as? Int8 {
+        return Float80(value)
+    } else if let value = value as? Int16 {
+        return Float80(value)
+    } else if let value = value as? Int32 {
+        return Float80(value)
+    } else if let value = value as? Int64 {
+        return Float80(value)
+    } else if let value = value as? UInt8 {
+        return Float80(value)
+    } else if let value = value as? UInt16 {
+        return Float80(value)
+    } else if let value = value as? UInt32 {
+        return Float80(value)
+    } else if let value = value as? UInt64 {
+        return Float80(value)
+    } else if let value = value as? Float80 {
+        return value
+    } else if let value = value as? Float64 {
+        return Float80(value)
+    } else if let value = value as? Float32 {
+        return Float80(value)
+    }
+
+    return nil
+}

Tests/StencilTests/ExpressionSpec.swift

@@ -72,6 +72,11 @@ func testExpressions() {
         let context = Context(dictionary: ["value": Double(0)])
         try expect(try expression.evaluate(context: context)).to.beFalse()
       }
+
+      $0.it("evaluates to false when uint is 0") {
+        let context = Context(dictionary: ["value": UInt(0)])
+        try expect(try expression.evaluate(context: context)).to.beFalse()
+      }
     }
 
     $0.describe("NotExpression") {