feat: support get private member method

exp/utils_above_1_18.go

@@ -0,0 +1,47 @@
+//go:build go1.18
+// +build go1.18
+
+/*
+ * Copyright 2023 ByteDance Inc.
+ *
+ * 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 exp
+
+import (
+	"unsafe"
+
+	"github.com/bytedance/mockey/internal/tool"
+	"github.com/bytedance/mockey/internal/unsafereflect"
+)
+
+// GetPrivateMemberMethod resolve a method from an instance, include private method.
+//
+// F must fit the shape of specific method, include receiver as the first argument.
+// Especially, the receiver can be replaced as interface when F is declaring,
+// this will be very useful when receiver type is not exported for other packages.
+//
+// for example:
+//
+//	GetPrivateMemberMethod[func(*bytes.Buffer) bool](&bytes.Buffer{}, "empty")
+//	GetPrivateMemberMethod[func(hash.Hash) [sha256.Size]byte](sha256.New(), "checkSum")
+func GetPrivateMemberMethod[F interface{}](instance interface{}, methodName string) interface{} {
+	tfn, ok := unsafereflect.MethodByName(instance, methodName)
+	if !ok {
+		tool.Assert(false, "can't reflect instance method :%v", methodName)
+		return nil
+	}
+	// return with (unsafe) function type cast
+	return *(*F)(unsafe.Pointer(&tfn))
+}

exp/utils_above_1_18_test.go

@@ -0,0 +1,69 @@
+//go:build go1.18
+// +build go1.18
+
+/*
+ * Copyright 2023 ByteDance Inc.
+ *
+ * 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 exp
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/bytedance/mockey"
+	"github.com/bytedance/mockey/internal/tool"
+	"github.com/smartystreets/goconvey/convey"
+)
+
+func TestGetPrivateMemberMethod(t *testing.T) {
+	mockey.PatchConvey("FakeMethod", t, func() {
+		convey.So(func() {
+			GetPrivateMemberMethod[func()](&bytes.Buffer{}, "FakeMethod")
+		}, convey.ShouldPanicWith, "can't reflect instance method :FakeMethod")
+	})
+
+	mockey.PatchConvey("OriginalGetMethod", t, func() {
+		convey.So(func() {
+			mockey.GetMethod(&bytes.Buffer{}, "empty")
+		}, convey.ShouldPanicWith, "can't reflect instance method :empty")
+	})
+
+	mockey.PatchConvey("ExportFunc", t, func() {
+		convey.So(func() {
+			exportedFunc := GetPrivateMemberMethod[func(*bytes.Buffer) int](&bytes.Buffer{}, "Len")
+			var mocked bool
+			mockey.Mock(exportedFunc).To(func(buffer *bytes.Buffer) int {
+				mocked = true
+				return 0
+			}).Build()
+			_ = new(bytes.Buffer).Len()
+			tool.Assert(mocked, "function should be mocked")
+		}, convey.ShouldNotPanic)
+	})
+
+	mockey.PatchConvey("PrivateFunc", t, func() {
+		convey.So(func() {
+			privateFunc := GetPrivateMemberMethod[func(*bytes.Buffer) bool](&bytes.Buffer{}, "empty")
+			var mocked bool
+			mockey.Mock(privateFunc).To(func(buffer *bytes.Buffer) bool {
+				mocked = true
+				return true
+			}).Build()
+			_, _ = new(bytes.Buffer).ReadByte()
+			tool.Assert(mocked, "function should be mocked")
+		}, convey.ShouldNotPanic)
+	})
+}

internal/unsafereflect/name_above_1_17.go

@@ -0,0 +1,53 @@
+//go:build go1.17
+// +build go1.17
+
+/*
+ * Copyright 2023 ByteDance Inc.
+ *
+ * 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 unsafereflect
+
+import "unsafe"
+
+// name is an encoded type name with optional extra data.
+type name struct {
+	bytes *byte
+}
+
+func (n name) data(off int, whySafe string) *byte {
+	return (*byte)(add(unsafe.Pointer(n.bytes), uintptr(off), whySafe))
+}
+
+func (n name) readVarint(off int) (int, int) {
+	v := 0
+	for i := 0; ; i++ {
+		x := *n.data(off+i, "read varint")
+		v += int(x&0x7f) << (7 * i)
+		if x&0x80 == 0 {
+			return i + 1, v
+		}
+	}
+}
+
+func (n name) name() (s string) {
+	if n.bytes == nil {
+		return
+	}
+	i, l := n.readVarint(1)
+	hdr := (*_String)(unsafe.Pointer(&s))
+	hdr.Data = unsafe.Pointer(n.data(1+i, "non-empty string"))
+	hdr.Len = l
+	return
+}

internal/unsafereflect/name_below_1_17.go

@@ -0,0 +1,41 @@
+//go:build !go1.17
+// +build !go1.17
+
+/*
+ * Copyright 2023 ByteDance Inc.
+ *
+ * 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 unsafereflect
+
+import (
+	"unsafe"
+)
+
+// name is an encoded type name with optional extra data.
+type name struct {
+	bytes *byte
+}
+
+func (n name) name() (s string) {
+	if n.bytes == nil {
+		return
+	}
+	b := (*[4]byte)(unsafe.Pointer(n.bytes))
+
+	hdr := (*_String)(unsafe.Pointer(&s))
+	hdr.Data = unsafe.Pointer(&b[3])
+	hdr.Len = int(b[1])<<8 | int(b[2])
+	return s
+}