fix(if): Empty strings should be falsy

Sources/Expression.swift

@@ -52,6 +52,8 @@ final class VariableExpression: Expression, CustomStringConvertible {
       truthy = !result.isEmpty
     } else if let result = result as? Bool {
       truthy = result
+    } else if let result = result as? String {
+      truthy = !result.isEmpty
     } else if let value = result, let result = toNumber(value: value) {
       truthy = result > 0
     } else if result != nil {

Tests/StencilTests/ExpressionSpec.swift

@@ -45,6 +45,16 @@ func testExpressions() {
         try expect(try expression.evaluate(context: context)).to.beTrue()
       }
 
+      $0.it("evaluates to true with string") {
+        let context = Context(dictionary: ["value": "test"])
+        try expect(try expression.evaluate(context: context)).to.beTrue()
+      }
+
+      $0.it("evaluates to false when empty string") {
+        let context = Context(dictionary: ["value": ""])
+        try expect(try expression.evaluate(context: context)).to.beFalse()
+      }
+
       $0.it("evaluates to false when integer value is below 0 or below") {
         let context = Context(dictionary: ["value": 0])
         try expect(try expression.evaluate(context: context)).to.beFalse()

Tests/StencilTests/IfNodeSpec.swift

@@ -3,172 +3,6 @@ import Spectre
 
 
 func testIfNode() {
-  describe("Expression") {
-    $0.describe("VariableExpression") {
-      let expression = VariableExpression(variable: Variable("value"))
-
-      $0.it("evaluates to true when value is not nil") {
-        let context = Context(dictionary: ["value": "known"])
-        try expect(try expression.evaluate(context: context)).to.beTrue()
-      }
-
-      $0.it("evaluates to false when value is unset") {
-        let context = Context()
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-
-      $0.it("evaluates to true when array variable is not empty") {
-        let items: [[String: Any]] = [["key":"key1","value":42],["key":"key2","value":1337]]
-        let context = Context(dictionary: ["value": [items]])
-        try expect(try expression.evaluate(context: context)).to.beTrue()
-      }
-
-      $0.it("evaluates to false when array value is empty") {
-        let emptyItems = [[String: Any]]()
-        let context = Context(dictionary: ["value": emptyItems])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-
-      $0.it("evaluates to false when dictionary value is empty") {
-        let emptyItems = [String:Any]()
-        let context = Context(dictionary: ["value": emptyItems])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-
-      $0.it("evaluates to false when Array<Any> value is empty") {
-        let context = Context(dictionary: ["value": ([] as [Any])])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-
-      $0.it("evaluates to true when integer value is above 0") {
-        let context = Context(dictionary: ["value": 1])
-        try expect(try expression.evaluate(context: context)).to.beTrue()
-      }
-
-      $0.it("evaluates to false when integer value is below 0 or below") {
-        let context = Context(dictionary: ["value": 0])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-
-        let negativeContext = Context(dictionary: ["value": 0])
-        try expect(try expression.evaluate(context: negativeContext)).to.beFalse()
-      }
-
-      $0.it("evaluates to true when float value is above 0") {
-        let context = Context(dictionary: ["value": Float(0.5)])
-        try expect(try expression.evaluate(context: context)).to.beTrue()
-      }
-
-      $0.it("evaluates to false when float is 0 or below") {
-        let context = Context(dictionary: ["value": Float(0)])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-
-      $0.it("evaluates to true when double value is above 0") {
-        let context = Context(dictionary: ["value": Double(0.5)])
-        try expect(try expression.evaluate(context: context)).to.beTrue()
-      }
-
-      $0.it("evaluates to false when double is 0 or below") {
-        let context = Context(dictionary: ["value": Double(0)])
-        try expect(try expression.evaluate(context: context)).to.beFalse()
-      }
-    }
-
-    $0.describe("NotExpression") {
-      $0.it("returns truthy for positive expressions") {
-        let expression = NotExpression(expression: StaticExpression(value: true))
-        try expect(expression.evaluate(context: Context())).to.beFalse()
-      }
-
-      $0.it("returns falsy for negative expressions") {
-        let expression = NotExpression(expression: StaticExpression(value: false))
-        try expect(expression.evaluate(context: Context())).to.beTrue()
-      }
-    }
-
-    $0.describe("expression parsing") {
-      $0.it("can parse a variable expression") {
-        let expression = try parseExpression(components: ["value"])
-        try expect(expression.evaluate(context: Context())).to.beFalse()
-        try expect(expression.evaluate(context: Context(dictionary: ["value": true]))).to.beTrue()
-      }
-
-      $0.it("can parse a not expression") {
-        let expression = try parseExpression(components: ["not", "value"])
-        try expect(expression.evaluate(context: Context())).to.beTrue()
-        try expect(expression.evaluate(context: Context(dictionary: ["value": true]))).to.beFalse()
-      }
-
-      $0.describe("and expression") {
-        let expression = try! parseExpression(components: ["lhs", "and", "rhs"])
-
-        $0.it("evaluates to false with lhs false") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": true]))).to.beFalse()
-        }
-
-        $0.it("evaluates to false with rhs false") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": false]))).to.beFalse()
-        }
-
-        $0.it("evaluates to false with lhs and rhs false") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": false]))).to.beFalse()
-        }
-
-        $0.it("evaluates to true with lhs and rhs true") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": true]))).to.beTrue()
-        }
-      }
-
-      $0.describe("or expression") {
-        let expression = try! parseExpression(components: ["lhs", "or", "rhs"])
-
-        $0.it("evaluates to true with lhs true") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": false]))).to.beTrue()
-        }
-
-        $0.it("evaluates to true with rhs true") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": true]))).to.beTrue()
-        }
-
-        $0.it("evaluates to true with lhs and rhs true") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": true, "rhs": true]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with lhs and rhs false") {
-          try expect(expression.evaluate(context: Context(dictionary: ["lhs": false, "rhs": false]))).to.beFalse()
-        }
-      }
-
-      $0.describe("multiple expression") {
-        let expression = try! parseExpression(components: ["one", "or", "two", "and", "not", "three"])
-
-        $0.it("evaluates to true with one") {
-          try expect(expression.evaluate(context: Context(dictionary: ["one": true]))).to.beTrue()
-        }
-
-        $0.it("evaluates to true with one and three") {
-          try expect(expression.evaluate(context: Context(dictionary: ["one": true, "three": true]))).to.beTrue()
-        }
-
-        $0.it("evaluates to true with two") {
-          try expect(expression.evaluate(context: Context(dictionary: ["two": true]))).to.beTrue()
-        }
-
-        $0.it("evaluates to false with two and three") {
-          try expect(expression.evaluate(context: Context(dictionary: ["two": true, "three": true]))).to.beFalse()
-        }
-
-        $0.it("evaluates to false with two and three") {
-          try expect(expression.evaluate(context: Context(dictionary: ["two": true, "three": true]))).to.beFalse()
-        }
-
-        $0.it("evaluates to false with nothing") {
-          try expect(expression.evaluate(context: Context())).to.beFalse()
-        }
-      }
-    }
-  }
-
   describe("IfNode") {
     $0.describe("parsing") {
       $0.it("can parse an if block") {

docs/builtins.rst

@@ -48,6 +48,7 @@ true the contents of the block are processed. Being true is defined as:
 * Being non-empty (dictionaries or arrays)
 * Not being a false boolean value
 * Not being a numerical value of 0 or below
+* Not being an empty string
 
 .. code-block:: html+django