Fix conditional statement (#109)

* Add tests to identify the bug

* Fix the rendering bug

The else branch got pre-rendered, despite the condition.

Author: mattesmohr

Sources/HTMLKit/Framework/Environment/Statements/BranchStatements.swift

@@ -9,24 +9,16 @@
 /// The statement is for
 public struct IF: GlobalElement {
 
-    public enum IFPrerenderErrors: Error {
-        
-        case dynamiclyEvaluatedCondition
-    }
-    
     internal class Condition {
 
         internal let condition: Conditionable
 
-        internal var formula: Formula
-        
-        internal var view: AnyContent
+        internal var content: AnyContent
 
         internal init(condition: Conditionable) {
 
             self.condition = condition
-            self.view = ""
-            self.formula = Formula()
+            self.content = ""
         }
     }
 
@@ -39,39 +31,39 @@ public struct IF: GlobalElement {
     public init(_ condition: Conditionable, @ContentBuilder<AnyContent> content: () -> AnyContent) {
 
         let condition = Condition(condition: condition)
-        condition.view = content()
+        condition.content = content()
 
         self.conditions = [condition]
     }
 
     public func elseIf(_ condition: Conditionable, @ContentBuilder<AnyContent> content: () -> AnyContent) -> IF {
 
         let condition = Condition(condition: condition)
-        condition.view = content()
+        condition.content = content()
 
         return .init(conditions: conditions + [condition])
     }
 
     public func elseIf<T>(isNil path: TemplateValue<T?>, @ContentBuilder<AnyContent> content: () -> AnyContent) -> IF {
 
         let condition = Condition(condition: IsNullCondition<T>(lhs: path))
-        condition.view = content()
+        condition.content = content()
 
         return .init(conditions: conditions + [condition])
     }
 
     public func elseIf<T>(isNotNil path: TemplateValue<T?>, @ContentBuilder<AnyContent> content: () -> AnyContent) -> IF {
 
         let condition = Condition(condition: NotNullCondition<T>(lhs: path))
-        condition.view = content()
+        condition.content = content()
 
         return .init(conditions: conditions + [condition])
     }
 
     public func `else`(@ContentBuilder<AnyContent> content: () -> AnyContent) -> IF {
 
         let condition = Condition(condition: AlwaysTrueCondition())
-        condition.view = content()
+        condition.content = content()
 
         return .init(conditions: conditions + [condition])
     }
@@ -84,7 +76,7 @@ extension IF: AnyContent {
         IF(conditions: conditions.map { htmlCondition in
 
             let scriptCondition = IF.Condition(condition: htmlCondition.condition)
-            scriptCondition.view = htmlCondition.view.scripts
+            scriptCondition.content = htmlCondition.content.scripts
 
             return scriptCondition
         })
@@ -95,31 +87,22 @@ extension IF: AnyContent {
         var isStaticallyEvaluated = true
 
         for condition in conditions {
-            
-            condition.formula.calendar = formula.calendar
-            
-            condition.formula.timeZone = formula.timeZone
 
             do {
 
                 guard isStaticallyEvaluated else {
-                    throw IFPrerenderErrors.dynamiclyEvaluatedCondition
+                    break
                 }
 
-                let testContext = ContextManager<Void>(contexts: [:])
-                
-                if try condition.condition.evaluate(with: testContext) {
+                if try condition.condition.evaluate(with: ContextManager<Void>(contexts: [:])) {
 
-                    try condition.view.prerender(formula)
+                    try condition.content.prerender(formula)
 
-                    return // Returning as the first true condition should be the only one that is rendered
+                    break
                 }
 
             } catch {
-                
                 isStaticallyEvaluated = false
-                
-                try condition.prerender(formula)
             }
         }
 
@@ -144,11 +127,11 @@ extension IF: AnyContent {
 extension IF.Condition: AnyContent {
 
     public func prerender(_ formula: Formula) throws {
-        try view.prerender(formula)
+        try content.prerender(formula)
     }
 
     public func render<T>(with manager: ContextManager<T>) throws -> String {
-        return try formula.render(with: manager)
+        return try content.render(with: manager)
     }
 }
 

Tests/HTMLKitTests/StatementsTests.swift

@@ -15,7 +15,7 @@ final class StatementsTests: XCTestCase {
 
     var renderer = Renderer()
 
-    func testIfStatement() throws {
+    func testIfStatementWithConstantValue() throws {
 
         let isValid: TemplateValue<Bool> = .constant(true)
 
@@ -40,7 +40,37 @@ final class StatementsTests: XCTestCase {
         )
     }
 
-    func testElseStatement() throws {
+    func testIfStatementWithVariableValue() throws {
+        
+        struct TestContext {
+            var isValid: Bool
+        }
+        
+        @TemplateValue(TestContext.self)
+        var item
+        
+        let page = TestPage {
+            IF(item.isValid) {
+                Paragraph {
+                    "true"
+                }
+            }.else {
+                Paragraph {
+                    "false"
+                }
+            }
+        }
+        
+        try renderer.add(layout: page)
+        
+        XCTAssertEqual(try renderer.render(layout: TestPage.self, with: TestContext(isValid: true)),
+                       """
+                       <p>true</p>
+                       """
+        )
+    }
+    
+    func testElseStatementWithConstantValue() throws {
 
         let isValid: TemplateValue<Bool> = .constant(false)
 
@@ -65,6 +95,36 @@ final class StatementsTests: XCTestCase {
         )
     }
 
+    func testElseStatementWithVariableValue() throws {
+        
+        struct TestContext {
+            var isValid: Bool
+        }
+        
+        @TemplateValue(TestContext.self)
+        var item
+        
+        let page = TestPage {
+            IF(item.isValid) {
+                Paragraph {
+                    "true"
+                }
+            }.else {
+                Paragraph {
+                    "false"
+                }
+            }
+        }
+        
+        try renderer.add(layout: page)
+        
+        XCTAssertEqual(try renderer.render(layout: TestPage.self, with: TestContext(isValid: false)),
+                       """
+                       <p>false</p>
+                       """
+        )
+    }
+    
     func testElseIfStatement() throws {
 
         let age: TemplateValue<Int> = .constant(16)