add ExtractTune use case

tests/unit/AbcParser/Application/UseCases/ExtractTuneFromCollectionTest.php

@@ -0,0 +1,41 @@
+<?php
+
+use XaiCorp\AbcParser\Application\UseCases\ExtractTuneFromCollection;
+use XaiCorp\AbcParser\Application\UseCases\ImportAbcFile;
+
+class ExtractTuneFromCollectionTest extends \Codeception\Test\Unit
+{
+    /**
+     * @param string $filename
+     * @return bool|string
+     */
+    private function getAbc($filename = '/abc/valid_abc_1.abc')
+    {
+        return file_get_contents(codecept_data_dir($filename));
+    }
+
+    public function testCreate()
+    {
+        $abc = $this->getAbc();
+        $tunes = ImportAbcFile::create()->import($abc);
+
+        $extractor = ExtractTuneFromCollection::create($tunes);
+
+        $this->assertInstanceOf(ExtractTuneFromCollection::class, $extractor);
+    }
+
+    public function testExtractTuneByTitle()
+    {
+        $title = "Emmett's Hedgehog";
+
+        $abc = $this->getAbc('/abc/jigs.abc');
+        $tunes = ImportAbcFile::create()->import($abc);
+
+        $extractor = ExtractTuneFromCollection::create($tunes);
+
+        $result = $extractor->extractTuneByTitle($title);
+
+        $this->assertCount(1, $result);
+        $this->assertNotEquals($tunes, $result);
+    }
+}