Add some scalachecks roundtrips for more confidence, fixes #29

1 files changed, 63 insertions, 0 deletions

diff --git a/src/test/scala/spray/json/RoundTripSpecs.scala b/src/test/scala/spray/json/RoundTripSpecs.scala
new file mode 100644
index 0000000..51df48d
--- /dev/null
+++ b/src/test/scala/spray/json/RoundTripSpecs.scala
@@ -0,0 +1,63 @@
+package spray.json
+
+import org.specs2.mutable.Specification
+import org.scalacheck._
+import org.specs2.matcher.ScalaCheckMatchers
+
+object JsValueGenerators {
+  import Gen._
+  import Arbitrary.arbitrary
+
+  // some characters have special meaning in parboiled
+  // see org.parboiled.support.Chars, we have to exclude those
+  val parseableString: Gen[String] = arbitrary[String].map(_.filterNot(_ > 0xfd00))
+  val genString: Gen[JsString] = parseableString.map(JsString(_))
+  val genBoolean: Gen[JsBoolean] = oneOf(JsFalse, JsTrue)
+  val genLongNumber: Gen[JsNumber] = arbitrary[Long].map(JsNumber(_))
+  val genIntNumber: Gen[JsNumber] = arbitrary[Long].map(JsNumber(_))
+  val genDoubleNumber: Gen[JsNumber] = arbitrary[Long].map(JsNumber(_))
+  def genArray(depth: Int): Gen[JsArray] =
+    if (depth == 0) JsArray()
+    else
+      for {
+        n <- choose(0, 15)
+        els <- Gen.containerOfN[List, JsValue](n, genValue(depth - 1))
+      } yield JsArray(els)
+  def genField(depth: Int): Gen[(String, JsValue)] =
+    for {
+      key <- parseableString
+      value <- genValue(depth)
+    } yield key -> value
+  def genObject(depth: Int): Gen[JsObject] =
+    if (depth == 0) JsObject()
+    else
+      for {
+        n <- choose(0, 15)
+        fields <- Gen.containerOfN[List, (String, JsValue)](n, genField(depth - 1))
+      } yield JsObject(fields)
+
+  def genValue(depth: Int): Gen[JsValue] =
+    oneOf(
+      JsNull: Gen[JsValue],
+      genString,
+      genBoolean,
+      genLongNumber,
+      genDoubleNumber,
+      genIntNumber,
+      genArray(depth),
+      genObject(depth))
+  implicit val arbitraryValue: Arbitrary[JsValue] = Arbitrary(genValue(5))
+}
+
+class RoundTripSpecs extends Specification with ScalaCheckMatchers {
+  import JsValueGenerators.arbitraryValue
+
+  "Parsing / Printing round-trip" should {
+    "starting from JSON using compactPrint" in prop { (json: JsValue) =>
+      json.compactPrint.parseJson must_== json
+    }
+    "starting from JSON using prettyPrint" in prop { (json: JsValue) =>
+      json.prettyPrint.parseJson must_== json
+    }
+  }
+}