Moving a couple of classes from ODB (#915)

modules/core/shared/src/main/scala/lucuma/core/enums/ScienceBand.scala

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+// Copyright (c) 2016-2023 Association of Universities for Research in Astronomy, Inc. (AURA)
+// For license information see LICENSE or https://opensource.org/licenses/BSD-3-Clause
+
+package lucuma.core.enums
+
+import lucuma.core.util.Enumerated
+
+enum ScienceBand(val tag: String) derives Enumerated:
+  case Band1 extends ScienceBand("band1")
+  case Band2 extends ScienceBand("band2")
+  case Band3 extends ScienceBand("band3")
+  case Band4 extends ScienceBand("band4")

modules/core/shared/src/main/scala/lucuma/core/util/DateInterval.scala

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+// Copyright (c) 2016-2023 Association of Universities for Research in Astronomy, Inc. (AURA)
+// For license information see LICENSE or https://opensource.org/licenses/BSD-3-Clause
+
+package lucuma.core.util
+
+import cats.Eq
+import cats.syntax.order.*
+import org.typelevel.cats.time.*
+
+import java.time.LocalDate
+import java.time.Period
+import java.time.temporal.ChronoUnit
+
+/**
+ * Interval between a start date (inclusive) and an end date (exclusive).
+ */
+sealed class DateInterval private (val start: LocalDate, val end: LocalDate):
+  assert(start <= end, s"start date ($start) must be <= end date ($end)")
+
+  def isEmpty: Boolean =
+    start === end
+
+  def isNonEmpty: Boolean =
+    !isEmpty
+
+  def period: Period =
+    start.until(end)
+
+  def days: Long =
+    ChronoUnit.DAYS.between(start, end)
+
+object DateInterval:
+
+  given Eq[DateInterval] =
+    Eq.by(a => (a.start, a.end))
+
+  /**
+   * Creates an interval between the two dates, swapping the order if
+   * necessary.  If d0 comes before d1, the interval is [d0, d1).  Otherwise
+   * it is [d1, d0).  The start date (the lesser of the two inputs) is
+   * inclusive while the end date is exclusive.
+   */
+  def between(d0: LocalDate, d1: LocalDate): DateInterval =
+    if (d0 <= d1) new DateInterval(d0, d1) else new DateInterval(d1, d0)

modules/testkit/src/main/scala/lucuma/core/util/arb/ArbDateInterval.scala

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+// Copyright (c) 2016-2023 Association of Universities for Research in Astronomy, Inc. (AURA)
+// For license information see LICENSE or https://opensource.org/licenses/BSD-3-Clause
+
+package lucuma.core.util
+package arb
+
+import org.scalacheck.*
+import org.scalacheck.Arbitrary.arbitrary
+
+import java.time.LocalDate
+
+trait ArbDateInterval {
+
+  given Arbitrary[DateInterval] =
+    Arbitrary {
+      for {
+        d0 <- arbitrary[LocalDate]
+        d1 <- arbitrary[LocalDate]
+      } yield DateInterval.between(d0, d1)
+    }
+
+  given Cogen[DateInterval] =
+    Cogen[(LocalDate, LocalDate)].contramap { a => (a.start, a.end) }
+
+}
+
+object ArbDateInterval extends ArbDateInterval

modules/tests/shared/src/test/scala/lucuma/core/util/DateIntervalSuite.scala

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+// Copyright (c) 2016-2023 Association of Universities for Research in Astronomy, Inc. (AURA)
+// For license information see LICENSE or https://opensource.org/licenses/BSD-3-Clause
+
+package lucuma.core.util
+
+import cats.kernel.laws.discipline.*
+import lucuma.core.util.arb.ArbDateInterval
+import munit.DisciplineSuite
+import org.scalacheck.Prop.forAll
+
+class DateIntervalSuite extends DisciplineSuite {
+
+  import ArbDateInterval.given
+
+  checkAll("Eq", EqTests[DateInterval].eqv)
+
+  test("period in days") {
+    forAll { (interval: DateInterval) =>
+      assertEquals(interval.start.plusDays(interval.days), interval.end)
+    }
+  }
+
+}