Rock, paper, scissors

Fixes #1

tests/RockPaperScissorsTest.php

@@ -0,0 +1,72 @@
+<?php
+
+use Assert\AssertionFailedException;
+
+beforeEach(function () {
+    $this->game = new App\RockPaperScissorsGame();
+});
+
+it('throws an exception for an empty first move', function () {
+    $this->game->firstMove('');
+})->throws(AssertionFailedException::class, 'You must specify a move.');
+
+it('throws an exception for an empty second move', function () {
+    $this->game->secondMove('');
+})->throws(AssertionFailedException::class, 'You must specify a move.');
+
+it('throws an exception if an invalid first move is entered', function () {
+    $this->game->firstMove('banana');
+})->throws(AssertionFailedException::class, 'You must enter a valid move. banana given.');
+
+it('throws an exception if an invalid second move is entered', function () {
+    $this->game->secondMove('apple');
+})->throws(AssertionFailedException::class, 'You must enter a valid move. apple given.');
+
+it('returns the result of two different valid moves', function (
+    string $firstMove,
+    string $secondMove,
+    string $winner
+) {
+    $this->game
+        ->firstMove($firstMove)
+        ->secondMove($secondMove);
+
+    assertSame($winner, $this->game->getWinner());
+})->with([
+    [
+        'firstMove' => 'rock',
+        'secondMove' => 'paper',
+        'winner' => 'paper',
+    ],
+    [
+        'firstMove' => 'paper',
+        'secondMove' => 'rock',
+        'winner' => 'paper',
+    ],
+    [
+        'firstMove' => 'rock',
+        'secondMove' => 'scissors',
+        'winner' => 'scissors',
+    ],
+    [
+        'firstMove' => 'scissors',
+        'secondMove' => 'rock',
+        'winner' => 'scissors',
+    ],
+    [
+        'firstMove' => 'scissors',
+        'secondMove' => 'paper',
+        'winner' => 'scissors',
+    ],
+    [
+        'firstMove' => 'paper',
+        'secondMove' => 'scissors',
+        'winner' => 'scissors',
+    ],
+]);
+
+test('it returns null if there is a tie', function (string $move) {
+   $this->game->firstMove($move)->secondMove($move);
+
+   assertNull($this->game->getWinner());
+})->with(['rock', 'paper', 'scissors']);