Throw InvalidReturnException if IfElse condition returns a non-boolean. Address CR requests.

Author: Mark Challoner

README.md

@@ -583,6 +583,8 @@ $data = [
 
 Delegates to one expression or another depending on whether the specified condition strictly evaluates to true.
 
+If the condition does not return a boolean an InvalidReturnException will be thrown.
+
 #### Signature
 
 ```php
@@ -645,8 +647,6 @@ Test if all items in $data are even.
 
 Delegates to one expression or another depending on whether the specified condition maps to null.
 
-Deprecated. Use IfElse and Exists strategies instead.
-
 #### Signature
 
 ```php

src/InvalidReturnException.php

@@ -0,0 +1,10 @@
+<?php
+namespace ScriptFUSION\Mapper;
+
+/**
+ * The exception that is thrown when an invalid return value from a callback is specified.
+ */
+class InvalidReturnException extends \RuntimeException
+{
+    // Intentionally empty.
+}

src/Strategy/IfElse.php

@@ -1,6 +1,7 @@
 <?php
 namespace ScriptFUSION\Mapper\Strategy;
 
+use ScriptFUSION\Mapper\InvalidReturnException;
 use ScriptFUSION\Mapper\Mapping;
 
 /**
@@ -25,8 +26,8 @@ class IfElse extends Delegate
      */
     public function __construct(callable $condition, $if, $else = null)
     {
-        $this->condition = $condition;
         parent::__construct($if);
+        $this->condition = $condition;
         $this->else = $else;
     }
 
@@ -37,11 +38,19 @@ public function __construct(callable $condition, $if, $else = null)
      * @param mixed $data
      * @param mixed $context
      *
+     * @throws InvalidReturnException
+     *
      * @return mixed
      */
     public function __invoke($data, $context = null)
     {
-        if (call_user_func($this->condition, $data, $context) === true) {
+        $return = call_user_func($this->condition, $data, $context);
+
+        if (!is_bool($return)) {
+            throw new InvalidReturnException('Invalid return from condition: must be of type boolean.');
+        }
+
+        if ($return === true) {
             return parent::__invoke($data, $context);
         }
 

src/Strategy/IfExists.php

@@ -20,8 +20,12 @@ class IfExists extends IfElse
      */
     public function __construct(Strategy $condition, $if, $else = null)
     {
-        parent::__construct(function ($data, $context = null) use ($condition) {
-            return $this->delegate($condition, $data, $context) !== null;
-        }, $if, $else);
+        parent::__construct(
+            function ($data, $context = null) use ($condition) {
+                return $this->delegate($condition, $data, $context) !== null;
+            },
+            $if,
+            $else
+        );
     }
 }

test/Integration/Mapper/Strategy/IfElseTest.php

@@ -2,6 +2,7 @@
 namespace ScriptFUSIONTest\Integration\Mapper\Strategy;
 
 use Mockery\Adapter\Phpunit\MockeryPHPUnitIntegration;
+use ScriptFUSION\Mapper\InvalidReturnException;
 use ScriptFUSION\Mapper\Mapper;
 use ScriptFUSION\Mapper\Strategy\Exists;
 use ScriptFUSION\Mapper\Strategy\IfElse;
@@ -38,8 +39,10 @@ public function testOnlyIf()
         self::assertNull($ifElse([]));
     }
 
-    public function testNonStrict()
+    public function testStrictness()
     {
+        $this->setExpectedException(InvalidReturnException::class);
+
         $ifElse = (new IfElse(
             function () {
                 return 1;
@@ -48,6 +51,6 @@ function () {
             'bar'
         ))->setMapper(new Mapper);
 
-        self::assertSame('bar', $ifElse([]));
+        $ifElse([]);
     }
 }