gomock mockgen : unknown embedded interface

Issue

mockgen -source=./driver/rocket_driver.go -destination ./driver/rocket_driver_mock.go -package driver
2022/06/01 21:39:44 Loading input failed: ./driver/rocket_driver.go:6:2: unknown embedded interface INavigatorDriver
make: *** [mockgen_rocket_driver] Error 1

https://github.com/golang/mock/issues/178

Here are my test files:

github.com/anyuser/test/test1.go:

package test

type A interface {
    Method1()
}

github.com/anyuser/test/test2.go:

package test

type B interface {
    A
}

Here's generation:

mockgen -source test2.go -destination test2_mocks.go -package test -aux_files test=test1.go

Error result:

Loading input failed: test2.go:4:2: unknown embedded interface A

Embedded Interfaces in aux_files

Embedded interfaces in aux_files generate unknown embedded interface XXX errors. See below for example of the problem:

// source
import (
    alias "some.org/package/imported"
)

type Source interface {
    alias.Foreign
}
// some.org/package/imported
type Foreign interface {
    Embedded
}

type Embedded interface {}

Attempting to generate a mock will result in an unknown embedded interface Embedded. The issue is that the fileParser stores auxInterfaces underneath the package name explicitly specified in the aux_files flag.

In the parseInterface method, there is an incorrect assumption about an embedded interface always being in the source file.

case *ast.Ident:
        // Embedded interface in this package.
        ei := p.auxInterfaces[""][v.String()]
        if ei == nil {
                return nil, p.errorf(v.Pos(), "unknown embedded interface %s", v.String())
        }

https://pkg.go.dev/github.com/golang/mock/mockgen/internal/tests/aux_imports_embedded_interface#section-readme

Solution

不要把 rocket_driver.go 跟其他依赖的 interface 放到同一个 package 下面 ( mockgen 的默认假设? ) .

mockgen -source=./rocket/rocket_driver.go 
-destination ./rocket/rocket_driver_mock.go 
-package rocket 
-aux_files rocket=service/basic_info_service.go,rocket=driver/navigator_driver.go

type IRocketFetcher interface {
    service.BasicInfoService
    driver.INavigatorDriver
}

type RocketFetcher struct {
}

func NewRocketFetcher() *RocketFetcher { return &RocketFetcher{} }

源代码工程目录:

.
├── Makefile
├── README.md
├── alpha
│   ├── cql.go
│   ├── cql_compiler.go
│   ├── cql_compiler_test.go
│   └── cql_util.go
├── component
│   ├── component.go
│   └── component_test.go
├── constant
│   └── sql_key.go
├── datasource
│   └── data_source.go
├── driver
│   ├── navigator_driver.go
│   ├── navigator_driver_mock.go
│   ├── navigator_driver_mock_data.go
│   ├── sqlite_driver.go
│   └── sqlite_driver_test.go
├── go.mod
├── go.sum
├── lang
│   └── lang.go
├── onetable
│   ├── one_table.go
│   └── one_table_test.go
├── rocket
│   ├── basic_common.go
│   ├── basic_common_test.go
│   ├── index_common.go
│   ├── rocket_fetcher.go
│   ├── rocket_fetcher_mock.go
│   ├── rocket_fetcher_test.go
│   ├── rsd.go
│   └── rsd_test.go
├── service
│   ├── basic_info_service.go
│   ├── basic_info_service_mock.go
│   └── basic_info_service_test.go
├── stream
│   ├── parallel.go
│   ├── parallel_test.go
│   ├── ring.go
│   ├── ring_test.go
│   ├── stream.go
│   └── stream_test.go
├── stringx
│   ├── node.go
│   ├── node_fuzz_test.go
│   ├── node_test.go
│   ├── random.go
│   ├── random_test.go
│   ├── replacer.go
│   ├── replacer_fuzz_test.go
│   ├── replacer_test.go
│   ├── strings.go
│   ├── strings_test.go
│   ├── trie.go
│   └── trie_test.go
├── test_report.html
├── threading
│   ├── coroutinegroup.go
│   ├── coroutinegroup_test.go
│   ├── recover.go
│   ├── recover_test.go
│   ├── routines.go
│   ├── routines_test.go
│   ├── taskrunner.go
│   ├── taskrunner_test.go
│   ├── workergroup.go
│   └── workergroup_test.go
├── udfs
│   ├── indexation_convert.go
│   └── udf.go
└── utils
    ├── basic
    │   ├── basic_common.go
    │   ├── basic_constu.go
    │   ├── basic_util.go
    │   └── hotsoon_item_pack.go
    ├── chart
    │   └── chart_common.go
    ├── co
    │   ├── concurrent.go
    │   └── concurrent_test.go
    ├── convert.go
    ├── copy
    │   ├── copier.go
    │   └── errors.go
    ├── dimu
    │   └── dimu.go
    ├── indexu
    │   ├── constu.go
    │   ├── indexu.go
    │   └── parse_request.go
    ├── modelu
    │   ├── error.go
    │   └── model.go
    ├── numberu
    │   └── numberu.go
    ├── rocket_constu
    │   └── constu.go
    ├── slicesu
    │   └── slicesu.go
    ├── stringu
    │   └── stringu.go
    ├── structu
    │   └── structu.go
    └── timeu
        ├── date_type.go
        ├── timeu.go
        └── timeu_test.go

27 directories, 86 files

mockgen 指令参数说明

-source : 
A file containing interfaces to be mocked.
 
-destination :
A file to which to write the resulting source code. 
If you don't set this, the code is printed to standard output.

-package :
The package to use for the resulting mock class source code. 
If you don't set this, the package name is mock_ concatenated with the package of the input file.
 
-imports :
A list of explicit imports that should be used in the resulting source code,
 specified as a comma-separated list of elements of the form `foo=bar/baz` , 
where `bar/baz`  is the package being imported ,  
and `foo`  is the identifier to use for the package in the generated source code.
 
-aux_files: 
A list of additional files that should be consulted to resolve 
e.g. embedded interfaces defined in a different file. 

This is specified as a comma-separated list of elements of the form foo=bar/baz.go, 
where bar/baz.go is the source file 
and foo is the package name of that file used by the -source file.
 
-build_flags: 
(reflect mode only) Flags passed verbatim to go build.
 
-mock_names: 
A list of custom names for generated mocks. This is specified as a comma-separated list of elements of the form Repository=MockSensorRepository,Endpoint=MockSensorEndpoint, where Repository is the interface name and MockSensorRepository is the desired mock name (mock factory method and mock recorder will be named after the mock). If one of the interfaces has no custom name specified, then default naming convention will be used.
 
 
-copyright_file: Copyright file used to add copyright header to the resulting source code.

Go语言中接口组合(接口中包含接口)

在Go语言中，可以在接口A中组合其它的一个或多个接口(如接口B、C)，这种方式等价于在接口A中添加接口B、C中声明的方法。

//接口中可以组合其它接口，这种方式等效于在接口中添加其它接口的方法
type Reader interface {
    read()
}
type Writer interface {
    write()
}

//定义上述两个接口的实现类
type MyReadWrite struct{}

func (mrw *MyReadWrite) read() {
    fmt.Println("MyReadWrite...read")
}

func (mrw *MyReadWrite) write() {
    fmt.Println("MyReadWrite...write")
}

//定义一个接口，组合了上述两个接口
type ReadWriter interface {
    Reader
    Writer
}

//上述接口等价于：
type ReadWriterV2 interface {
    read()
    write()
}

//ReadWriter和ReadWriterV2两个接口是等效的，因此可以相互赋值
func interfaceTest0104() {
    mrw := &MyReadWrite{}
    //mrw对象实现了read()方法和write()方法，因此可以赋值给ReadWriter和ReadWriterV2
    var rw1 ReadWriter = mrw
    rw1.read()
    rw1.write()

    fmt.Println("------")
    var rw2 ReadWriterV2 = mrw
    rw2.read()
    rw2.write()

    //同时，ReadWriter和ReadWriterV2两个接口对象可以相互赋值
    rw1 = rw2
    rw2 = rw1
}

参考资料

https://stackoverflow.com/questions/55999405/how-can-i-mock-specific-embedded-method-inside-interface

https://pkg.go.dev/github.com/golang/mock/gomock

https://github.com/golang/mock#running-mockgen