Introduce the notion of HasLegalValues and HasIllegalValues

nrinaudo · Apr 24, 2020 · a96657c · a96657c
1 parent 407c222
commit a96657c
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Showing 25 changed files with 408 additions and 46 deletions.
diff --git a/core/jvm/src/test/scala/kantan/codecs/strings/DateCodecTests.scala b/core/jvm/src/test/scala/kantan/codecs/strings/DateCodecTests.scala
@@ -18,13 +18,21 @@ package kantan.codecs.strings
 
 import java.text.SimpleDateFormat
 import java.util.{Date, Locale}
+import kantan.codecs.laws.{HasIllegalValues, HasLegalValues}
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
 import kantan.codecs.laws.discipline.arbitrary._
 
 class DateCodecTests extends DisciplineSuite {
+  val format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSz", Locale.ENGLISH)
 
   implicit val codec: StringCodec[Date] =
-    StringCodec.dateCodec(new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSz", Locale.ENGLISH))
+    StringCodec.dateCodec(format)
+
+  implicit val hasLegalValues: HasLegalValues[String, Date, codecs.type] =
+    HasLegalValues.from(date => format.synchronized(format.format(date)))
+
+  implicit val hasIllegalValues: HasIllegalValues[String, Date, codecs.type] =
+    HasIllegalValues.fromUnsafeString(s => format.synchronized(format.parse(s)))
 
   checkAll("StringDecoder[Date]", StringCodecTests[Date].decoder[Int, Int])
   checkAll("StringEncoder[Date]", StringCodecTests[Date].encoder[Int, Int])

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/BigDecimalCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/BigDecimalCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
-import kantan.codecs.laws.discipline.arbitrary._
 
 class BigDecimalCodecTests extends DisciplineSuite {
 

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/BigIntCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/BigIntCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
-import kantan.codecs.laws.discipline.arbitrary._
 
 class BigIntCodecTests extends DisciplineSuite {
 

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/BooleanCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/BooleanCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
-import kantan.codecs.laws.discipline.arbitrary._
 
 class BooleanCodecTests extends DisciplineSuite {
 

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/ByteCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/ByteCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
-import kantan.codecs.laws.discipline.arbitrary._
 
 class ByteCodecTests extends DisciplineSuite {
 

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/CharCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/CharCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
-import kantan.codecs.laws.discipline.arbitrary._
 
 class CharCodecTests extends DisciplineSuite {
 

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/DoubleCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/DoubleCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
-import kantan.codecs.laws.discipline.arbitrary._
 
 class DoubleCodecTests extends DisciplineSuite {
 

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/EitherCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/EitherCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringDecoderTests, StringEncoderTests}
-import kantan.codecs.laws.discipline.arbitrary._
 import kantan.codecs.strings.tagged._
 
 class EitherCodecTests extends DisciplineSuite {

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/FloatCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/FloatCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
-import kantan.codecs.laws.discipline.arbitrary._
 
 class FloatCodecTests extends DisciplineSuite {
 

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/IntCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/IntCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
-import kantan.codecs.laws.discipline.arbitrary._
 
 class IntCodecTests extends DisciplineSuite {
 

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/LongCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/LongCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
-import kantan.codecs.laws.discipline.arbitrary._
 
 class LongCodecTests extends DisciplineSuite {
 

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/OptionCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/OptionCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringDecoderTests, StringEncoderTests}
-import kantan.codecs.laws.discipline.arbitrary._
 import kantan.codecs.strings.tagged._
 
 class OptionCodecTests extends DisciplineSuite {

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/ShortCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/ShortCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
-import kantan.codecs.laws.discipline.arbitrary._
 
 class ShortCodecTests extends DisciplineSuite {
 

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/StringsCodecTests.scala b/core/shared/src/test/scala/kantan/codecs/strings/StringsCodecTests.scala
@@ -17,7 +17,6 @@
 package kantan.codecs.strings
 
 import kantan.codecs.laws.discipline.{DisciplineSuite, StringCodecTests}
-import kantan.codecs.laws.discipline.arbitrary._
 
 class StringsCodecTests extends DisciplineSuite {
 

diff --git a/core/shared/src/test/scala/kantan/codecs/strings/tagged.scala b/core/shared/src/test/scala/kantan/codecs/strings/tagged.scala
@@ -19,6 +19,7 @@ package kantan.codecs.strings
 import imp.imp
 import kantan.codecs.{Codec, Decoder, Encoder}
 import kantan.codecs.laws.{DecoderLaws, EncoderLaws}
+import kantan.codecs.laws.{HasIllegalStringValues, HasIllegalValues, HasLegalStringValues, HasLegalValues}
 import kantan.codecs.laws.CodecValue.LegalValue
 import kantan.codecs.laws.discipline.{DecoderTests => RootDecoderTests, EncoderTests => RootEncoderTests}
 import kantan.codecs.laws.discipline.arbitrary._
@@ -32,13 +33,15 @@ object tagged {
 
   // - Type aliases for readability ------------------------------------------------------------------------------------
   // -------------------------------------------------------------------------------------------------------------------
-  type DecoderTests[D]      = RootDecoderTests[String, D, DecodeError, tagged.type]
-  type EncoderTests[D]      = RootEncoderTests[String, D, tagged.type]
-  type TaggedDecoder[D]     = Decoder[String, D, DecodeError, tagged.type]
-  type TaggedEncoder[D]     = Encoder[String, D, tagged.type]
-  type TaggedDecoderLaws[D] = DecoderLaws[String, D, DecodeError, tagged.type]
-  type TaggedEncoderLaws[D] = EncoderLaws[String, D, tagged.type]
-  type TaggedLegalValue[D]  = LegalValue[String, D, tagged.type]
+  type DecoderTests[D]           = RootDecoderTests[String, D, DecodeError, tagged.type]
+  type EncoderTests[D]           = RootEncoderTests[String, D, tagged.type]
+  type TaggedDecoder[D]          = Decoder[String, D, DecodeError, tagged.type]
+  type TaggedEncoder[D]          = Encoder[String, D, tagged.type]
+  type TaggedDecoderLaws[D]      = DecoderLaws[String, D, DecodeError, tagged.type]
+  type TaggedEncoderLaws[D]      = EncoderLaws[String, D, tagged.type]
+  type TaggedLegalValue[D]       = LegalValue[String, D, tagged.type]
+  type HasLegalTaggedValues[D]   = HasLegalValues[String, D, tagged.type]
+  type HasIllegalTaggedValues[D] = HasIllegalValues[String, D, tagged.type]
 
   // - Specialised tests -----------------------------------------------------------------------------------------------
   // -------------------------------------------------------------------------------------------------------------------
@@ -76,4 +79,10 @@ object tagged {
   def codec[D: StringCodec]: Codec[String, D, DecodeError, tagged.type] =
     imp[StringCodec[D]].tag[tagged.type]
 
+  implicit def hasLegalValues[D](implicit hlv: HasLegalStringValues[D]): HasLegalTaggedValues[D] =
+    hlv.tag[tagged.type]
+
+  implicit def hasIllegalValues[D](implicit hiv: HasIllegalStringValues[D]): HasIllegalTaggedValues[D] =
+    hiv.tag[tagged.type]
+
 }
diff --git a/laws/js/src/main/scala/kantan/codecs/laws/PlatformSpecificHasIllegalValues.scala b/laws/js/src/main/scala/kantan/codecs/laws/PlatformSpecificHasIllegalValues.scala
@@ -0,0 +1,19 @@
+/*
+ * Copyright 2016 Nicolas Rinaudo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kantan.codecs.laws
+
+trait PlatformSpecificHasIllegalValues
diff --git a/laws/js/src/main/scala/kantan/codecs/laws/PlatformSpecificHasLegalValues.scala b/laws/js/src/main/scala/kantan/codecs/laws/PlatformSpecificHasLegalValues.scala
@@ -0,0 +1,19 @@
+/*
+ * Copyright 2016 Nicolas Rinaudo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kantan.codecs.laws
+
+trait PlatformSpecificHasLegalValues
diff --git a/laws/jvm/src/main/scala/kantan/codecs/laws/PlatformSpecificHasIllegalValues.scala b/laws/jvm/src/main/scala/kantan/codecs/laws/PlatformSpecificHasIllegalValues.scala
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2016 Nicolas Rinaudo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kantan.codecs.laws
+
+import java.io.File
+import java.net.URL
+import java.nio.file.{Path, Paths}
+import kantan.codecs.laws.HasIllegalValues._
+
+trait PlatformSpecificHasIllegalValues {
+
+  implicit val url: HasIllegalStringValues[URL]   = fromUnsafeString(e => new URL(e))
+  implicit val path: HasIllegalStringValues[Path] = fromUnsafeString(e => Paths.get(e.toString))
+  implicit val file: HasIllegalStringValues[File] = fromUnsafeString(e => new File(e))
+
+}
diff --git a/laws/jvm/src/main/scala/kantan/codecs/laws/PlatformSpecificHasLegalValues.scala b/laws/jvm/src/main/scala/kantan/codecs/laws/PlatformSpecificHasLegalValues.scala
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2016 Nicolas Rinaudo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kantan.codecs.laws
+
+import java.io.File
+import java.net.URL
+import java.nio.file.Path
+import kantan.codecs.laws.HasLegalValues._
+
+trait PlatformSpecificHasLegalValues {
+
+  implicit val url: HasLegalStringValues[URL]   = fromToString
+  implicit val path: HasLegalStringValues[Path] = fromToString
+  implicit val file: HasLegalStringValues[File] = fromToString
+
+}
diff --git a/laws/shared/src/main/scala/kantan/codecs/laws/CodecValue.scala b/laws/shared/src/main/scala/kantan/codecs/laws/CodecValue.scala
@@ -16,33 +16,66 @@
 
 package kantan.codecs.laws
 
-// TODO: investigate what type variance annotations can be usefully applied to CodecValue.
+import imp.imp
+import org.scalacheck.{Arbitrary, Gen, Shrink}
+
+/** Represents possible encoded and decoded values.
+  *
+  * There are two main categories of values:
+  * - legal ones: an encoded / decoded couple, where decoding one should yield the other and vice versa.
+  * - illegal ones: an encoded value that cannot be decoded.
+  *
+  * The purpose of this type is to test encoder, decoder and codec laws - which means we'll almost always need
+  * `Arbitrary` instances for them. These can be tedious to write, but that tedium can be alleviated somewhat through
+  * the [[HasIllegalValues]] and [[HasLegalValues]] type classes.
+  */
 sealed abstract class CodecValue[Encoded, Decoded, Tag] extends Product with Serializable {
   def encoded: Encoded
   def mapEncoded[E](f: Encoded => E): CodecValue[E, Decoded, Tag]
   def mapDecoded[D](f: Decoded => D): CodecValue[Encoded, D, Tag]
-  def tag[T]: CodecValue[Encoded, Decoded, T]
-
   def isLegal: Boolean
   def isIllegal: Boolean = !isLegal
+  def tag[T]: CodecValue[Encoded, Decoded, T]
 }
 
 object CodecValue {
+
+  /** Represents a legal value: one that can be safely encoded and decoded. */
   final case class LegalValue[Encoded, Decoded, Tag](encoded: Encoded, decoded: Decoded)
       extends CodecValue[Encoded, Decoded, Tag] {
 
     override def mapDecoded[D](f: Decoded => D) = LegalValue(encoded, f(decoded))
     override def mapEncoded[E](f: Encoded => E) = LegalValue(f(encoded), decoded)
+    override val isLegal                        = true
     @SuppressWarnings(Array("org.wartremover.warts.AsInstanceOf"))
-    override def tag[T]  = this.asInstanceOf[LegalValue[Encoded, Decoded, T]]
-    override val isLegal = true
+    override def tag[T]: LegalValue[Encoded, Decoded, T] = this.asInstanceOf[LegalValue[Encoded, Decoded, T]]
   }
 
+  /** Represents an illegal value: one that cannot be decoded. */
   final case class IllegalValue[Encoded, Decoded, Tag](encoded: Encoded) extends CodecValue[Encoded, Decoded, Tag] {
     override def mapDecoded[D](f: Decoded => D) = IllegalValue(encoded)
     override def mapEncoded[E](f: Encoded => E) = IllegalValue(f(encoded))
+    override val isLegal                        = false
     @SuppressWarnings(Array("org.wartremover.warts.AsInstanceOf"))
-    override def tag[T]  = this.asInstanceOf[IllegalValue[Encoded, Decoded, T]]
-    override val isLegal = false
+    override def tag[T]: IllegalValue[Encoded, Decoded, T] = this.asInstanceOf[IllegalValue[Encoded, Decoded, T]]
   }
+
+  // - Arbitrary instances ---------------------------------------------------------------------------------------------
+  // -------------------------------------------------------------------------------------------------------------------
+  implicit def arbValue[E, D, T](
+    implicit arbLegal: Arbitrary[LegalValue[E, D, T]],
+    arbIllegal: Arbitrary[IllegalValue[E, D, T]]
+  ): Arbitrary[CodecValue[E, D, T]] =
+    Arbitrary(Gen.oneOf(arbLegal.arbitrary, arbIllegal.arbitrary))
+
+  implicit def arbLegalValue[E, D: Arbitrary, T](
+    implicit alv: HasLegalValues[E, D, T]
+  ): Arbitrary[LegalValue[E, D, T]] =
+    Arbitrary(imp[Arbitrary[D]].arbitrary.map(alv.asLegalValue))
+
+  implicit def arbIllegalValue[E: Arbitrary, D, T](
+    implicit aiv: HasIllegalValues[E, D, T]
+  ): Arbitrary[IllegalValue[E, D, T]] =
+    Arbitrary(imp[Arbitrary[E]].arbitrary.map(aiv.asIllegalValue))
+
 }