Refactor main files to test files

src/test/scala/db/DBServiceSpec.scala

@@ -0,0 +1,35 @@
+package db
+
+import cats.effect.unsafe.implicits.global
+import org.scalatest.funsuite.AnyFunSuite
+import org.scalatest.matchers.should.Matchers
+
+import java.time.format.DateTimeFormatter
+import java.time.{LocalDate, LocalDateTime}
+
+
+class DBServiceSpec extends AnyFunSuite with Matchers {
+  private val dateFormatter = DateTimeFormatter.ofPattern("yyyyMMdd_HHmm")
+
+  test("getDateFileNames should return correct file names") {
+    val dbService = DBService.of.unsafeRunSync()
+    val datesList = dbService.getDateFileNames(LocalDate.of(2023, 5, 15))
+      .unsafeRunSync()
+
+    val expectedFileNames = (0 to 23).toList
+      .map(hour => if (hour < 10) "0" + hour else "" + hour)
+      .map(str => s"20230515_${str}30.csv")
+
+    datesList shouldBe expectedFileNames
+  }
+
+  test("getInRange should return correct count of lines") {
+    val from = LocalDateTime.parse("20230513_2200", dateFormatter)
+    val to = LocalDateTime.parse("20230516_1230", dateFormatter)
+
+    val dbService = DBService.of.unsafeRunSync()
+    val lines = dbService.getInRange(from, to).unsafeRunSync()
+
+    lines.length shouldBe 2142
+  }
+}