fix(for tag): Potential ‘Index out of range’ crash

Fixes #136

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Stencil Changelog
 
+## Master
+
+### Bug Fixes
+
+- Fixes a potential crash when using the `{% for %}` template tag with the
+  incorrect amount of arguments.
+
+
 ## 0.9.0
 
 ### Enhancements

Sources/ForTag.swift

@@ -10,7 +10,7 @@ class ForNode : NodeType {
   class func parse(_ parser:TokenParser, token:Token) throws -> NodeType {
     let components = token.components()
 
-    guard components.count >= 2 && components[2] == "in" &&
+    guard components.count >= 3 && components[2] == "in" &&
         (components.count == 4 || (components.count >= 6 && components[4] == "where")) else {
       throw TemplateSyntaxError("'for' statements should use the following 'for x in y where condition' `\(token.contents)`.")
     }

Tests/StencilTests/ForNodeSpec.swift

@@ -134,6 +134,15 @@ func testForNode() {
       let node = ForNode(resolvable: Variable("dict"), loopVariables: ["key", "value"], nodes: nodes, emptyNodes: emptyNodes, where: nil)
       try expect(try node.render(context)) == "oneItwoII"
     }
+
+    $0.it("handles invalid input") {
+      let tokens: [Token] = [
+          .block(value: "for i"),
+      ]
+      let parser = TokenParser(tokens: tokens, environment: Environment())
+      let error = TemplateSyntaxError("'for' statements should use the following 'for x in y where condition' `for i`.")
+      try expect(try parser.parse()).toThrow(error)
+    }
   }
 }