only cast null constructor args for primitives (#520)

* only cast null for primitives

before, we tried to cast applied types to the type arguments, to capture context bounds. That fails for simple generic types
that then get cast to the wrong type. However, that's all unnessecary: the only nulls we need to cast are primitives, which can't
be passed as null. Anyting else doesn't need a cast at all

* add failing tests

* ignore failing tests

* fix class type parameters

* add tests from passer-by

* move test that don't (yet) pass on scala 2 to scala 3 specific testsuite

* simply getting target

shared/src/main/scala-3/org/scalamock/clazz/MockMaker.scala

@@ -40,14 +40,28 @@ private[clazz] object MockMaker:
 
     def asParent(tree: TypeTree): TypeTree | Term =
       val constructorFieldsFilledWithNulls: List[List[Term]] =
+        // we don't care about any of the parameters, and just want to pass null, since all interesting parts will be mocked.
+        // that's simpler said than done, because if type of the argument is a primitive
+        // then null needs to be cast to that primitive type.
+        // the type could be a generic type though, which could resolve to a primitive, so we need to find the type the param
+        // should resolve to, and cast it if needed.
+        val paramsMap = {
+          val abstractParams = tree.tpe.dealias.typeSymbol.primaryConstructor.paramSymss.filter(_.exists(_.isType)).flatten
+          val resolvedParams = tpe.widen match
+            case AppliedType(_, params) => params
+            case _ => Nil
+          abstractParams.zip(resolvedParams).toMap
+        }
+
         tree.tpe.dealias.typeSymbol.primaryConstructor.paramSymss
           .filterNot(_.exists(_.isType))
-          .map(_.map(_.info.widen match {
-            case t@AppliedType(inner, applied) =>
-              Select.unique('{null}.asTerm, "asInstanceOf").appliedToTypes(List(inner.appliedTo(tpe.typeArgs)))
-            case other =>
-              Select.unique('{null}.asTerm, "asInstanceOf").appliedToTypes(List(other))
-          }))
+          .map(_.map{ sym =>
+            val target = paramsMap.getOrElse(sym.info.typeSymbol, sym.info).widen.dealias
+            if target <:< TypeRepr.of[AnyVal] then
+              Select.unique('{null}.asTerm, "asInstanceOf").appliedToType(target)
+            else
+              '{null}.asTerm
+          })
 
       if constructorFieldsFilledWithNulls.forall(_.isEmpty) then
         tree

shared/src/test/scala-3/com/paulbutcher/test/MockTestScala3.scala

@@ -0,0 +1,62 @@
+package com.paulbutcher.test
+
+// Copyright (c) 2011-2015 ScalaMock Contributors (https://github.com/paulbutcher/ScalaMock/graphs/contributors)
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package com.paulbutcher.test.mock
+
+import org.scalamock.scalatest.MockFactory
+
+import com.paulbutcher.test._
+import org.scalatest.freespec.AnyFreeSpec
+import org.scalatest.matchers.should.Matchers
+
+class MockTestScala3 extends AnyFreeSpec with MockFactory with Matchers {
+
+  autoVerify = false
+
+  "In Scala 3, Mocks should" - {
+
+    "mock type constructor arguments" in {
+      class WithTC[TC[_]](tc: TC[Int])
+      type ID[A] = A
+      "mock[WithTC[List]]" should compile
+      pendingUntilFixed {
+        "mock[WithTC[ID]]" should compile
+      }
+    }
+
+    "mock generic arguments" in {
+      class WithGeneric[T](t: T)
+      "mock[WithGeneric[String]]" should compile
+      "mock[WithGeneric[Int]]" should compile
+    }
+
+    "mock type constructor context bounds" in {
+      trait Async[F[_]]
+      class A[F[_]: Async](val b: B[F])
+      class B[F[_]: Async](val c: C[F])
+      trait C[F[_]]
+      "mock[A[List]]" should compile
+      "mock[B[List]]" should compile
+      "mock[C[List]]" should compile
+    }
+  }
+}

shared/src/test/scala/com/paulbutcher/test/mock/MockTest.scala

@@ -488,5 +488,14 @@ class MockTest extends AnyFreeSpec with MockFactory with Matchers {
 
       "stub[HasNotifyMethod]" should compile
     }
+
+    "mock constructor arguments" in {
+      class WithOption(opt: Option[String])
+      class WithInt(i: Int)
+      class WithString(s: String)
+      "mock[WithOption]" should compile
+      "mock[WithInt]" should compile
+      "mock[WithString]" should compile
+    }
   }
 }