Adds tests

composer.json

@@ -13,5 +13,7 @@
             "Kavalanche\\Security\\": "src/"
         }
     },
-    "require": {}
+    "require": {
+        "phpunit/phpunit": "^8.4"
+    }
 }

phpunit.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/8.4/phpunit.xsd"
+         bootstrap="vendor/autoload.php"
+         executionOrder="depends,defects"
+         forceCoversAnnotation="true"
+         beStrictAboutCoversAnnotation="true"
+         beStrictAboutOutputDuringTests="true"
+         beStrictAboutTodoAnnotatedTests="true"
+         verbose="true">
+    <testsuites>
+        <testsuite name="default">
+            <directory suffix="Test.php">tests</directory>
+        </testsuite>
+    </testsuites>
+
+    <filter>
+        <whitelist processUncoveredFilesFromWhitelist="true">
+            <directory suffix=".php">src</directory>
+        </whitelist>
+    </filter>
+</phpunit>

tests/InMemoryUserProviderTest.php

@@ -0,0 +1,18 @@
+<?php
+
+class InMemoryUserProviderTest extends PHPUnit\Framework\TestCase {
+
+    public function testLoadUserByUsername_throwsOnError() {
+        $this->expectException(Exception::class);
+
+        $userProvider = new \Kavalanche\Security\InMemoryUserProvider();
+        $userProvider->loadUserByUsername('Kasia');
+    }
+
+    public function testLoadUserByUsername_returnsUser() {
+        $userProvider = new \Kavalanche\Security\InMemoryUserProvider();
+        $user = $userProvider->loadUserByUsername('Wojtek');
+        $this->assertInstanceOf(\Kavalanche\Security\UserInterface::class, $user);
+    }
+
+}