Added a custom generator for BigDecimals, to reduce somewhat the risk…

… of underflow
twitter · Oct 19, 2016 · c0a2d98 · c0a2d98
1 parent 22a7004
commit c0a2d98
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Showing 3 changed files with 15 additions and 7 deletions.
diff --git a/algebird-test/src/main/scala/com/twitter/algebird/BaseProperties.scala b/algebird-test/src/main/scala/com/twitter/algebird/BaseProperties.scala
@@ -16,16 +16,24 @@ limitations under the License.
 
 package com.twitter.algebird
 
-import org.scalacheck.Arbitrary
-import org.scalacheck.Prop
+import org.scalacheck.{Arbitrary, Gen, Prop}
 import org.scalacheck.Prop.forAll
+
 import scala.math.Equiv
 
 /**
  * Base properties useful for all tests using Algebird's typeclasses.
  */
 
 object BaseProperties {
+  implicit val arbReasonableBigDecimals: Arbitrary[BigDecimal] = Arbitrary(
+    for {
+      scale <- Gen.choose(-128, +128)
+      base <- implicitly[Arbitrary[BigInt]].arbitrary
+    } yield {
+      (BigDecimal(base) * BigDecimal(10).pow(scale))
+    })
+
   def defaultEq[T](t0: T, t1: T) = t0 == t1
 
   trait HigherEq[M[_]] {

diff --git a/algebird-test/src/test/scala/com/twitter/algebird/BatchedTest.scala b/algebird-test/src/test/scala/com/twitter/algebird/BatchedTest.scala
@@ -27,6 +27,7 @@ import Helpers.arbitraryBatched
 class BatchedLaws extends CheckProperties with Matchers with PropertyChecks {
 
   import BaseProperties._
+  implicit val arbReasonableBigDecimals = BaseProperties.arbReasonableBigDecimals
 
   def testBatchedMonoid[A: Arbitrary: Monoid](name: String, size: Int): Unit = {
     implicit val m: Monoid[Batched[A]] = Batched.compactingMonoid[A](size)
@@ -43,10 +44,10 @@ class BatchedLaws extends CheckProperties with Matchers with PropertyChecks {
   testBatchedMonoid[BigInt]("BigInt", 10)
   testBatchedMonoid[BigInt]("BigInt", 100)
   testBatchedMonoid[BigInt]("BigInt", 1000000)
-  testBatchedMonoid[BigDecimal]("BigDecimal", 1)
-  testBatchedMonoid[BigDecimal]("BigDecimal", 10)
-  testBatchedMonoid[BigDecimal]("BigDecimal", 100)
-  testBatchedMonoid[BigDecimal]("BigDecimal", 1000000)
+  testBatchedMonoid[BigDecimal]("BigDecimal", 1)(arbReasonableBigDecimals, implicitly[Monoid[BigDecimal]])
+  testBatchedMonoid[BigDecimal]("BigDecimal", 10)(arbReasonableBigDecimals, implicitly[Monoid[BigDecimal]])
+  testBatchedMonoid[BigDecimal]("BigDecimal", 100)(arbReasonableBigDecimals, implicitly[Monoid[BigDecimal]])
+  testBatchedMonoid[BigDecimal]("BigDecimal", 1000000)(arbReasonableBigDecimals, implicitly[Monoid[BigDecimal]])
   testBatchedMonoid[String]("String", 1)
   testBatchedMonoid[String]("String", 10)
   testBatchedMonoid[String]("String", 100)

diff --git a/algebird-test/src/test/scala/com/twitter/algebird/CountMinSketchTest.scala b/algebird-test/src/test/scala/com/twitter/algebird/CountMinSketchTest.scala
@@ -14,7 +14,6 @@ class CmsLaws extends PropSpec with PropertyChecks with Matchers {
 
   import BaseProperties._
 
-
   val DELTA = 1E-8
   val EPS = 0.005
   val SEED = 1