handle interfaces with generics

arguments/parser.go

@@ -91,7 +91,7 @@ func New(args []string, workingDir string, evaler Evaler, stater Stater) (*Parse
 }
 
 func (a *ParsedArguments) PrettyPrint() {
-	b, _ := json.Marshal(a)
+	b, _ := json.MarshalIndent(a, "", " ")
 	fmt.Println(string(b))
 }
 

fixtures/genericinterface/genericinterface.go

@@ -0,0 +1,46 @@
+package genericinterface
+
+//go:generate go run github.com/maxbrunsfeld/counterfeiter/v6 -generate
+
+type CustomTypeT any
+type CustomTypeU any
+
+// incorrect setup. this would fail
+// //counterfeiter:generate . GenericInterfaceBad[T CustomType]
+// type GenericInterfaceBad[T CustomTypeT] interface {
+// 	ReturnT() T
+// 	TakeT(T)
+// 	TakeAndReturnT(T) T
+// 	DoSomething()
+// }
+
+//counterfeiter:generate . GenericInterface
+type GenericInterface[T CustomTypeT] interface {
+	ReturnT() T
+	TakeT(T)
+	TakeAndReturnT(T) T
+	DoSomething()
+}
+
+//counterfeiter:generate . GenericInterfaceAny
+type GenericInterfaceAny[T any] interface {
+	ReturnT() T
+	TakeT(T)
+	TakeAndReturnT(T) T
+	DoSomething()
+}
+
+//counterfeiter:generate . GenericInterfaceMultipleTypes
+type GenericInterfaceMultipleTypes[T CustomTypeT, U CustomTypeU] interface {
+	ReturnT() T
+	ReturnU() U
+	ReturnTAndU() (T, U)
+	TakeT(T)
+	TakeU(U)
+	TakeTAndU(T, U)
+	TakeAndReturnT(T) T
+	TakeAndReturnU(U) U
+	TakeAndReturnTAndU(T, U) (T, U)
+	TakeTAndReturnU(T) U
+	DoSomething()
+}