Fix issue with indented partials (#19)

* Fix issue with indented partials

* Add test

* Add empty transform for string

Sources/HummingbirdMustache/Template+Render.swift

@@ -27,14 +27,16 @@ extension HBMustacheTemplate {
 
         if let indentation = context.indentation, indentation != "" {
             for token in tokens {
-                if string.last == "\n" {
+                let renderedString = self.renderToken(token, context: &context)
+                if renderedString != "", string.last == "\n" {
                     string += indentation
                 }
-                string += self.renderToken(token, context: &context)
+                string += renderedString
             }
         } else {
             for token in tokens {
-                string += self.renderToken(token, context: &context)
+                let result = self.renderToken(token, context: &context)
+                string += result
             }
         }
         return string

Sources/HummingbirdMustache/Transform.swift

@@ -39,6 +39,8 @@ public extension StringProtocol {
     /// - Returns: Result
     func transform(_ name: String) -> Any? {
         switch name {
+        case "empty":
+            return isEmpty
         case "capitalized":
             return capitalized
         case "lowercased":

Tests/HummingbirdMustacheTests/PartialTests.swift

@@ -42,6 +42,41 @@ final class PartialTests: XCTestCase {
         """)
     }
 
+    /// Test where last line of partial generates no content. It should not add a
+    /// tab either
+    func testPartialEmptyLineTabbing() throws {
+        let library = HBMustacheLibrary()
+        let template = try HBMustacheTemplate(string: """
+        <h2>Names</h2>
+        {{#names}}
+          {{> user}}
+        {{/names}}
+        Text after
+
+        """)
+        let template2 = try HBMustacheTemplate(string: """
+        {{^empty(.)}}
+        <strong>{{.}}</strong>
+        {{/empty(.)}}
+        {{#empty(.)}}
+        <strong>empty</strong>
+        {{/empty(.)}}
+
+        """)
+        library.register(template, named: "base")
+        library.register(template2, named: "user")
+
+        let object: [String: Any] = ["names": ["john", "adam", "claire"]]
+        XCTAssertEqual(library.render(object, withTemplate: "base"), """
+        <h2>Names</h2>
+          <strong>john</strong>
+          <strong>adam</strong>
+          <strong>claire</strong>
+        Text after
+
+        """)
+    }
+
     /// Testing dynamic partials
     func testDynamicPartials() throws {
         let library = HBMustacheLibrary()

Tests/HummingbirdMustacheTests/TemplateRendererTests.swift

@@ -82,7 +82,7 @@ final class TemplateRendererTests: XCTestCase {
         XCTAssertEqual(template.render(Test(string: nil)), "test ")
     }
 
-    func testOptionalSequence() throws {
+    func testOptionalSection() throws {
         struct Test {
             let string: String?
         }
@@ -94,6 +94,22 @@ final class TemplateRendererTests: XCTestCase {
         XCTAssertEqual(template2.render(Test(string: nil)), "test *")
     }
 
+    func testOptionalSequence() throws {
+        struct Test {
+            let string: String?
+        }
+        let template = try HBMustacheTemplate(string: "test {{#.}}{{string}}{{/.}}")
+        XCTAssertEqual(template.render([Test(string: "string")]), "test string")
+    }
+
+    func testOptionalSequenceSection() throws {
+        struct Test {
+            let string: String?
+        }
+        let template = try HBMustacheTemplate(string: "test {{#.}}{{#string}}*{{.}}{{/string}}{{/.}}")
+        XCTAssertEqual(template.render([Test(string: "string")]), "test *string")
+    }
+
     func testStructureInStructure() throws {
         struct SubTest {
             let string: String?