Add ability to replace type constraints

.mockery.yaml

@@ -41,6 +41,17 @@ packages:
         config:
           with-expecter: True
           unroll-variadic: False
+      # Replace generic params with a new constraint and a new fixed value
+      ReplaceGeneric:
+        config:
+          replace-type:
+            - github.com/vektra/mockery/v2/pkg/fixtures.ReplaceGeneric[-TImport]=github.com/vektra/mockery/v2/pkg/fixtures/redefined_type_b.B
+            - github.com/vektra/mockery/v2/pkg/fixtures.ReplaceGeneric[TConstraint]=github.com/vektra/mockery/v2/pkg/fixtures/constraints.String
+      # Replace a generic param with the parent type
+      ReplaceGenericSelf:
+        config:
+          replace-type:
+            - github.com/vektra/mockery/v2/pkg/fixtures.ReplaceGenericSelf[-T]=github.com/vektra/mockery/v2/pkg/fixtures.*ReplaceGenericSelf
   github.com/vektra/mockery/v2/pkg/fixtures/recursive_generation:
     config:
       recursive: True

Taskfile.yml

@@ -13,7 +13,7 @@ tasks:
       - "**/*.go"
     cmds:
       - go fmt ./...
-    
+
   mocks:
     desc: generate new mocks from scratch
     deps: [mocks.remove, mocks.generate]

docs/features.md

@@ -90,6 +90,63 @@ func (_m *Handler) HandleMessage(m pubsub.Message) error {
 }
 ```
 
+Generic type constraints can also be replaced by targeting the changed parameter with the square bracket notation on the left hand side.
+
+```shell
+mockery --replace-type github.com/vektra/mockery/v2/baz/internal/foo.InternalBaz[T]=github.com/vektra/mockery/v2/baz.Baz
+```
+
+For example:
+
+```go
+type InternalBaz[T any] struct{}
+
+func (*InternalBaz[T]) Foo() T {}
+
+// Becomes
+type InternalBaz[T baz.Baz] struct{}
+
+func (*InternalBaz[T]) Foo() T {}
+```
+
+If a type constraint needs to be removed and replaced with a type, target the constraint with square brackets and include a '-' in front to have it removed.
+
+```shell
+mockery --replace-type github.com/vektra/mockery/v2/baz/internal/foo.InternalBaz[-T]=github.com/vektra/mockery/v2/baz.Baz
+```
+
+For example:
+
+```go
+type InternalBaz[T any] struct{}
+
+func (*InternalBaz[T]) Foo() T {}
+
+// Becomes
+type InternalBaz struct{}
+
+func (*InternalBaz) Foo() baz.Baz {}
+```
+
+When replacing a generic constraint, you can replace the type with a pointer by adding a '*' before the output type name.
+
+```shell
+mockery --replace-type github.com/vektra/mockery/v2/baz/internal/foo.InternalBaz[-T]=github.com/vektra/mockery/v2/baz.*Baz
+```
+
+For example:
+
+```go
+type InternalBaz[T any] struct{}
+
+func (*InternalBaz[T]) Foo() T {}
+
+// Becomes
+type InternalBaz struct{}
+
+func (*InternalBaz) Foo() *baz.Baz {}
+```
+
 `packages` configuration
 ------------------------
 :octicons-tag-24: v2.21.0

pkg/fixtures/constraints/constraints.go

@@ -7,3 +7,7 @@ type Signed interface {
 type Integer interface {
 	~int
 }
+
+type String interface {
+	~string
+}

pkg/fixtures/generic.go

@@ -36,3 +36,17 @@ type GetInt interface{ Get() int }
 type GetGeneric[T constraints.Integer] interface{ Get() T }
 
 type EmbeddedGet[T constraints.Signed] interface{ GetGeneric[T] }
+
+type ReplaceGeneric[
+	TImport any,
+	TConstraint constraints.Signed,
+	TKeep any,
+] interface {
+	A(t1 TImport) TKeep
+	B() TImport
+	C() TConstraint
+}
+
+type ReplaceGenericSelf[T any] interface {
+	A() T
+}