Merge pull request #4216 from tmccarthy/tmccarthy/use-fractional-miniint

Use spurious `Fractional[MiniInt]` to test `Invariant[Fractional]`
typelevel · Jun 9, 2022 · 5f0a292 · 5f0a292
2 parents b351d67 + 75c8d09
commit 5f0a292
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diff --git a/tests/shared/src/test/scala-2.12/cats/tests/ScalaVersionSpecific.scala b/tests/shared/src/test/scala-2.12/cats/tests/ScalaVersionSpecific.scala
@@ -25,8 +25,6 @@ import cats.kernel.{Eq, Order}
 import cats.laws.discipline.{ExhaustiveCheck, MiniInt}
 import cats.laws.discipline.MiniInt._
 import cats.laws.discipline.eq._
-import cats.laws.discipline.DeprecatedEqInstances
-import org.scalacheck.Arbitrary
 
 trait ScalaVersionSpecificFoldableSuite
 trait ScalaVersionSpecificParallelSuite
@@ -35,7 +33,7 @@ trait ScalaVersionSpecificTraverseSuite
 
 trait ScalaVersionSpecificAlgebraInvariantSuite {
   // This version-specific instance is required since 2.12 and below do not have parseString on the Numeric class
-  protected val integralForMiniInt: Integral[MiniInt] = new Integral[MiniInt] {
+  protected trait MiniIntNumeric extends Numeric[MiniInt] {
     def compare(x: MiniInt, y: MiniInt): Int = Order[MiniInt].compare(x, y)
     def plus(x: MiniInt, y: MiniInt): MiniInt = x + y
     def minus(x: MiniInt, y: MiniInt): MiniInt = x + (-y)
@@ -46,8 +44,6 @@ trait ScalaVersionSpecificAlgebraInvariantSuite {
     def toLong(x: MiniInt): Long = x.toInt.toLong
     def toFloat(x: MiniInt): Float = x.toInt.toFloat
     def toDouble(x: MiniInt): Double = x.toInt.toDouble
-    def quot(x: MiniInt, y: MiniInt): MiniInt = MiniInt.unsafeFromInt(x.toInt / y.toInt)
-    def rem(x: MiniInt, y: MiniInt): MiniInt = MiniInt.unsafeFromInt(x.toInt % y.toInt)
   }
 
   // This version-specific instance is required since 2.12 and below do not have parseString on the Numeric class
@@ -75,24 +71,4 @@ trait ScalaVersionSpecificAlgebraInvariantSuite {
     )
   }
 
-  // This version-specific instance is required since 2.12 and below do not have parseString on the Numeric class
-  @annotation.nowarn("cat=deprecation")
-  implicit protected def eqFractional[A: Eq: Arbitrary]: Eq[Fractional[A]] = {
-    import DeprecatedEqInstances.catsLawsEqForFn1
-
-    Eq.by { fractional =>
-      (
-        fractional.compare _,
-        fractional.plus _,
-        fractional.minus _,
-        fractional.times _,
-        fractional.negate _,
-        fractional.fromInt _,
-        fractional.toInt _,
-        fractional.toLong _,
-        fractional.toFloat _,
-        fractional.toDouble _
-      )
-    }
-  }
 }
diff --git a/tests/shared/src/test/scala-2.13+/cats/tests/ScalaVersionSpecific.scala b/tests/shared/src/test/scala-2.13+/cats/tests/ScalaVersionSpecific.scala
@@ -23,15 +23,13 @@ package cats.tests
 
 import cats._
 import cats.data.NonEmptyLazyList
-import cats.laws.discipline.DeprecatedEqInstances
 import cats.laws.discipline.ExhaustiveCheck
 import cats.laws.discipline.MiniInt
 import cats.laws.discipline.NonEmptyParallelTests
 import cats.laws.discipline.ParallelTests
 import cats.laws.discipline.arbitrary._
 import cats.laws.discipline.eq._
 import cats.syntax.all._
-import org.scalacheck.Arbitrary
 import org.scalacheck.Prop._
 
 trait ScalaVersionSpecificFoldableSuite { self: FoldableSuiteAdditional =>
@@ -191,7 +189,7 @@ trait ScalaVersionSpecificTraverseSuite { self: TraverseSuiteAdditional =>
 trait ScalaVersionSpecificAlgebraInvariantSuite {
 
   // This version-specific instance is required since 2.12 and below do not have parseString on the Numeric class
-  protected val integralForMiniInt: Integral[MiniInt] = new Integral[MiniInt] {
+  protected trait MiniIntNumeric extends Numeric[MiniInt] {
     def compare(x: MiniInt, y: MiniInt): Int = Order[MiniInt].compare(x, y)
     def plus(x: MiniInt, y: MiniInt): MiniInt = x + y
     def minus(x: MiniInt, y: MiniInt): MiniInt = x + (-y)
@@ -202,8 +200,6 @@ trait ScalaVersionSpecificAlgebraInvariantSuite {
     def toLong(x: MiniInt): Long = x.toInt.toLong
     def toFloat(x: MiniInt): Float = x.toInt.toFloat
     def toDouble(x: MiniInt): Double = x.toInt.toDouble
-    def quot(x: MiniInt, y: MiniInt): MiniInt = MiniInt.unsafeFromInt(x.toInt / y.toInt)
-    def rem(x: MiniInt, y: MiniInt): MiniInt = MiniInt.unsafeFromInt(x.toInt % y.toInt)
     def parseString(str: String): Option[MiniInt] = Integral[Int].parseString(str).flatMap(MiniInt.fromInt)
   }
 
@@ -238,35 +234,6 @@ trait ScalaVersionSpecificAlgebraInvariantSuite {
     )
   }
 
-  // This version-specific instance is required since 2.12 and below do not have parseString on the Numeric class
-  @annotation.nowarn("cat=deprecation")
-  implicit protected def eqFractional[A: Eq: Arbitrary]: Eq[Fractional[A]] = {
-    // This deprecated instance is required since there is not `ExhaustiveCheck` for any types for which a `Fractional`
-    // can easily be defined
-    import DeprecatedEqInstances.catsLawsEqForFn1
-
-    Eq.by { fractional =>
-      val parseFloatStrings: Option[Double] => Option[A] = {
-        case Some(f) => fractional.parseString(f.toString)
-        case None    => fractional.parseString("invalid") // Use this to test parsing of non-numeric strings
-      }
-
-      (
-        fractional.compare _,
-        fractional.plus _,
-        fractional.minus _,
-        fractional.times _,
-        fractional.negate _,
-        fractional.fromInt _,
-        fractional.toInt _,
-        fractional.toLong _,
-        fractional.toFloat _,
-        fractional.toDouble _,
-        parseFloatStrings
-      )
-    }
-  }
-
 }
 
 class TraverseLazyListSuite extends TraverseSuite[LazyList]("LazyList")

diff --git a/tests/shared/src/test/scala/cats/tests/AlgebraInvariantSuite.scala b/tests/shared/src/test/scala/cats/tests/AlgebraInvariantSuite.scala
@@ -179,11 +179,14 @@ class AlgebraInvariantSuite extends CatsSuite with ScalaVersionSpecificAlgebraIn
   implicit private val arbCommutativeGroupInt: Arbitrary[CommutativeGroup[Int]] =
     Arbitrary(genCommutativeGroupInt)
 
+  protected val integralForMiniInt: Numeric[MiniInt] with Integral[MiniInt] = new MiniIntNumeric
+    with Integral[MiniInt] {
+    def quot(x: MiniInt, y: MiniInt): MiniInt = MiniInt.unsafeFromInt(x.toInt / y.toInt)
+    def rem(x: MiniInt, y: MiniInt): MiniInt = MiniInt.unsafeFromInt(x.toInt % y.toInt)
+  }
+
   implicit private val arbNumericMiniInt: Arbitrary[Numeric[MiniInt]] = Arbitrary(Gen.const(integralForMiniInt))
   implicit private val arbIntegralMiniInt: Arbitrary[Integral[MiniInt]] = Arbitrary(Gen.const(integralForMiniInt))
-  implicit private val arbFractionalFloat: Arbitrary[Fractional[Float]] = Arbitrary(
-    Gen.const(implicitly[Fractional[Float]])
-  )
 
   implicit protected def eqIntegral[A: Eq: ExhaustiveCheck]: Eq[Integral[A]] = {
     def makeDivisionOpSafe(unsafeF: (A, A) => A): (A, A) => Option[A] =
@@ -209,6 +212,14 @@ class AlgebraInvariantSuite extends CatsSuite with ScalaVersionSpecificAlgebraIn
     }
   }
 
+  implicit protected def eqFractional[A: Eq: ExhaustiveCheck]: Eq[Fractional[A]] =
+    Eq.by { fractional =>
+      (
+        fractional: Numeric[A],
+        fractional.div(_, _)
+      )
+    }
+
   checkAll("InvariantMonoidal[Semigroup]", SemigroupTests[Int](InvariantMonoidal[Semigroup].point(0)).semigroup)
   checkAll("InvariantMonoidal[CommutativeSemigroup]",
            CommutativeSemigroupTests[Int](InvariantMonoidal[CommutativeSemigroup].point(0)).commutativeSemigroup
@@ -218,10 +229,6 @@ class AlgebraInvariantSuite extends CatsSuite with ScalaVersionSpecificAlgebraIn
            InvariantSemigroupalTests[Monoid].invariantSemigroupal[Option[MiniInt], Option[Boolean], Option[Boolean]]
   )
 
-  checkAll("Invariant[Numeric]", InvariantTests[Numeric].invariant[MiniInt, Boolean, Boolean])
-  checkAll("Invariant[Integral]", InvariantTests[Integral].invariant[MiniInt, Boolean, Boolean])
-  checkAll("Invariant[Fractional]", InvariantTests[Fractional].invariant[Float, Boolean, Boolean])
-
   {
     val S: Semigroup[Int] = Semigroup[Int].imap(identity)(identity)
     checkAll("Semigroup[Int]", SemigroupTests[Int](S).semigroup)
@@ -310,6 +317,25 @@ class AlgebraInvariantSuite extends CatsSuite with ScalaVersionSpecificAlgebraIn
   checkAll("Invariant[CommutativeGroup]", InvariantTests[CommutativeGroup].invariant[MiniInt, Boolean, Boolean])
   checkAll("Invariant[CommutativeGroup]", SerializableTests.serializable(Invariant[CommutativeGroup]))
 
+  checkAll("Invariant[Numeric]", InvariantTests[Numeric].invariant[MiniInt, Boolean, Boolean])
+  checkAll("Invariant[Integral]", InvariantTests[Integral].invariant[MiniInt, Boolean, Boolean])
+
+  {
+    // This is a spurious instance since MiniInt is not a Fractional data type. But we use it since we don't have a
+    // Fractional type for which ExhaustiveCheck is also implemented. See https://github.com/typelevel/cats/pull/4033
+    val fractionalForMiniInt: Fractional[MiniInt] = new MiniIntNumeric with Fractional[MiniInt] {
+      def div(x: MiniInt, y: MiniInt): MiniInt =
+        if (y == MiniInt.zero) {
+          MiniInt.maxValue
+        } else {
+          x / y
+        }
+    }
+    implicit val arbFractionalMiniInt: Arbitrary[Fractional[MiniInt]] = Arbitrary(Gen.const(fractionalForMiniInt))
+
+    checkAll("Invariant[Fractional]", InvariantTests[Fractional].invariant[MiniInt, Boolean, Boolean])
+  }
+
   checkAll("InvariantMonoidal[Semigroup]",
            InvariantMonoidalTests[Semigroup].invariantMonoidal[Option[MiniInt], Option[Boolean], Option[Boolean]]
   )