Test for when exercise does not implement correct interface

Author: AydinHassan

test/Asset/CliExerciseMissingInterface.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace PhpSchool\PhpWorkshopTest\Asset;
+
+use PhpSchool\PhpWorkshop\Exercise\AbstractExercise;
+use PhpSchool\PhpWorkshop\Exercise\ExerciseInterface;
+use PhpSchool\PhpWorkshop\Exercise\ExerciseType;
+
+/**
+ * @author Aydin Hassan <aydin@hotmail.co.uk>
+ */
+class CliExerciseMissingInterface extends AbstractExercise implements ExerciseInterface
+{
+
+    /**
+     * Get the name of the exercise, like `Hello World!`.
+     *
+     * @return string
+     */
+    public function getName()
+    {
+        return 'CLI exercise missing interface';
+    }
+
+    /**
+     * A short description of the exercise.
+     *
+     * @return string
+     */
+    public function getDescription()
+    {
+        return 'CLI exercise missing interface';
+    }
+
+    /**
+     * Return the type of exercise. This is an ENUM. See `PhpSchool\PhpWorkshop\Exercise\ExerciseType`.
+     *
+     * @return ExerciseType
+     */
+    public function getType()
+    {
+        return ExerciseType::CLI();
+    }
+}

test/ExerciseRepositoryTest.php

@@ -2,10 +2,11 @@
 
 namespace PhpSchool\PhpWorkshopTest;
 
-use InvalidArgumentException;
+use PhpSchool\PhpWorkshop\Exception\InvalidArgumentException;
 use PhpSchool\PhpWorkshop\Exercise\ExerciseType;
 use PhpSchool\PhpWorkshopTest\Asset\CliExerciseImpl;
 use PhpSchool\PhpWorkshopTest\Asset\CliExerciseInterface;
+use PhpSchool\PhpWorkshopTest\Asset\CliExerciseMissingInterface;
 use PHPUnit_Framework_TestCase;
 use PhpSchool\PhpWorkshop\Exercise\ExerciseInterface;
 use PhpSchool\PhpWorkshop\ExerciseRepository;
@@ -81,4 +82,15 @@ public function testIterator()
         $repo = new ExerciseRepository($exercises);
         $this->assertEquals($exercises, iterator_to_array($repo));
     }
+
+    public function testExceptionIsThrownWhenTryingToAddExerciseWhichDoesNotImplementCorrectInterface()
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $message  = '"PhpSchool\PhpWorkshopTest\Asset\CliExerciseMissingInterface" is required to implement ';
+        $message .= '"PhpSchool\PhpWorkshop\Exercise\CliExercise", but it does not';
+        $this->expectExceptionMessage($message);
+
+        $exercise = new CliExerciseMissingInterface;
+        new ExerciseRepository([$exercise]);
+    }
 }