Implemented Todo class

tests/TodoTest.php

@@ -0,0 +1,67 @@
+<?php declare(strict_types=1);
+
+use MMK2410\MyTodoList\Todo;
+use MMK2410\MyTodoList\TodoStates;
+use PHPUnit\Framework\TestCase;
+
+class TodoTest extends TestCase
+{
+    public function testCreateTodo(): void
+    {
+        $title = "Some task";
+        $todo = new Todo($title);
+        $this->assertEquals(
+            $title,
+            $todo->getTitle(),
+            "Expected title '$title', but got '{$todo->getTitle()}'"
+        );
+    }
+
+    public function testDontCreateEmptyTodo(): void
+    {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage(Todo::ExceptionMsgInvalidTitle);
+        new Todo("");
+    }
+
+    public function testUpdateTitle(): void
+    {
+        $anotherTitle = "Another title";
+        $todo = new Todo("Some title");
+        $todo->setTitle($anotherTitle);
+        $this->assertEquals(
+            $anotherTitle,
+            $todo->getTitle(),
+            "Expected new title $anotherTitle, but got {$todo->getTitle()}"
+        );
+    }
+
+    public function testNewTodoState(): void
+    {
+        $todo = new Todo("stub");
+        $this->assertEquals(
+            TodoStates::Todo,
+            $todo->getStatus(),
+            "Expected todo state 'Todo', but got {$todo->getStatus()}"
+        );
+    }
+
+    public function testChangeTodoState(): void
+    {
+        $todo = new Todo("stub");
+        $todo->setState(TodoStates::Done);
+        $this->assertEquals(
+            TodoStates::Done,
+            $todo->getStatus(),
+            "Expected todo state 'Done', but got {$todo->getStatus()}"
+        );
+    }
+
+    public function testSetBogusTodoState(): void
+    {
+       $todo = new Todo("stub");
+       $this->expectException(\InvalidArgumentException::class);
+       $this->expectExceptionMessage("Invalid state tried to set.");
+       $todo->setState("bogus");
+    }
+}