setup approval tests with golden master using scalatest

scala/src/test/scala/com/gildedrose/GildedRoseApprovalTest.scala

@@ -1,38 +1,32 @@
 package com.gildedrose
 
-import org.approvaltests.Approvals
-import org.approvaltests.reporters.DiffReporter
-import org.approvaltests.reporters.UseReporter
-import org.junit.jupiter.api.Test
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
 
-import java.io.ByteArrayInputStream
-import java.io.ByteArrayOutputStream
-import java.io.PrintStream
+import java.io.{File, FileOutputStream}
+import scala.io.Source
 
-@UseReporter(Array(classOf[DiffReporter]))
-class GildedRoseApprovalTest {
+class GildedRoseApprovalTest extends AnyFlatSpec with Matchers {
+  it should "return the result of the golden master" in {
+    val fileWithTestResult = new File("approvaltests/gildedrose.testresult.txt")
+    val outputStream       = new FileOutputStream(fileWithTestResult)
+    Console.withOut(outputStream) {
 
-  @Test
-  def foo(): Unit = {
+      TexttestFixture.main(Array("30"))
+    }
 
-    val items: Array[Item] = Array(Item("foo", 0, 0))
-    val app: GildedRose    = new GildedRose(items)
-    app.updateQuality()
+    val approvedFile          = "approvaltests/gildedrose.approved.txt"
+    val sourceForTestResults  = Source.fromFile(fileWithTestResult)
+    val sourceForApprovedFile = Source.fromFile(approvedFile)
 
-    Approvals.verifyAll("Items", items)
+    val resultingOutput =
+      try sourceForTestResults.getLines().toVector
+      finally sourceForTestResults.close()
+    val approvedOutput =
+      try sourceForApprovedFile.getLines().toVector
+      finally sourceForTestResults.close()
+
+    resultingOutput should equal(approvedOutput)
   }
 
-  @Test
-  def thirtyDays(): Unit = {
-
-    val fakeoutput: ByteArrayOutputStream = new ByteArrayOutputStream()
-    System.setOut(new PrintStream(fakeoutput))
-    System.setIn(new ByteArrayInputStream("a\n".getBytes()))
-
-    val args: Array[String] = Array("30")
-    TexttestFixture.main(args)
-    val output: String = fakeoutput.toString()
-
-    Approvals.verify(output)
-  }
 }