bazel_gomock
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Code to create Go mocks for bazel targets using mockgen
gomock for Bazel
This skylark code allows you to generate code with mockgen
(from
golang/mock
) and use that code as a dependency in
your bazel projects. It handles all the GOPATH
stuff for you.
Setup
bazel_gomock
requires a rules_go
external to be set up in your WORKSPACE
as well as a go_repository
call for com_github_golang_mock
.
Then in your WORKSPACE
, add
# This commit is tagged as v1.3
bazel_gomock_commit = "fde78c91cf1783cc1e33ba278922ba67a6ee2a84"
http_archive(
name = "bazel_gomock",
sha256 = "692421b0c5e04ae4bc0bfff42fb1ce8671fe68daee2b8d8ea94657bb1fcddc0a",
strip_prefix = "bazel_gomock-{v}".format(v = bazel_gomock_commit),
urls = [
"https://github.com/jmhodges/bazel_gomock/archive/{v}.tar.gz".format(v = bazel_gomock_commit),
],
)
An example of a com_github_golang_mock
you'd need:
go_repository(
name = "com_github_golang_mock",
importpath = "github.com/golang/mock",
sum = "h1:l75CXGRSwbaYNpl/Z2X1XIIAMSCquvXgpVZDhwEIJsc=",
version = "v1.4.4",
)
Use
Once your WORKSPACE
is set up, you can call gomock
in your BUILD files like:
load("@bazel_gomock//:gomock.bzl", "gomock")
gomock(
name = "mock_sess",
out = "mock_sess_test.go",
interfaces = ["SessionsClient"],
library = "//proto/sessions/sessproto:go_default_library",
package = "main",
)
where library
is a go_library
target, interfaces
is the list of names of
the Go interfaces you'd like mockgen
to generate mocks of, package
is the
name of the Go package at the top of the generated file (in this example,
package "main"
), and out
is the path of generated source file that will be
made.
There is also a source
parameter described below.
You use this target's out
file directly in the srcs
parameter in go_test
,
go_library
, and so on. So, when the above example gomock
call is used in the
same BUILD file, you put mock_sess_test.go
in the srcs
parameter like so:
go_test(
name = "go_default_test",
srcs = [
"cool_test.go",
"mock_sess_test.go",
],
embed = [":go_default_library"]
...
)
If you need to generate mocks from a specific Go file instead of a
import path (say, because the go_library
you have is a main
package and is
therefore unreflectable by Go tools and specifically unimportable by mockgen
),
add the source
parameter with the location of source file. E.g. source = "//fancy/path:foo.go"
or just source = "foo.go"
if the file is in the same
directory). The library
parameter must still be set to the library that source
file lives in so that any referenced dependencies can be pulled into the Go
path.
Also, gazelle
will remove the generated source file from a go_test
target's
srcs
unless you end the generated file name with _test.go
.
As a likely unused feature, you can pass in an alternative
external for where to find the mockgen
tool target using the mockgen_tool
parameter. The only rule for the target is that must be a binary. The current
default is "@com_github_golang_mock//mockgen"
.
If you try to use gomock
on a go_library
that is in the package main
(and so
probably being immediately used as an embed
target for a go_binary
), you'll
get an annoying error like:
prog.go:13:2: import "your/main/package/deal" is a program, not an importable package
You can resolve that by setting the source
parameter to the location of the
file with the interfaces you want in it.
gomock
arguments:
Name | Default value | Type | Documentation |
---|---|---|---|
name | string | The name of the target. (Required.) | |
library | Label | The go_library to find the interfaces in. (Required.) | |
interfaces | list of string | The names of interfaces in library to generate mocks for. (Required if source is not set, and ignored if source is set.) |
|
source | string | Prefer using library only, instead of using this argument. The Go source file to generate interfaces from. If this is set, interfaces is ignored because mockgen will always generate code for all interfaces. See the gomock documentation on -source for more information. |
|
out | string | The file name to give the generated output. (Required.) | |
package | string | The package name to use in the generated output. See the gomock documentation on -package for more information. |
|
imports | string_dict | Dictionary of keys of package names and values of import paths to use the keys as the identifier to use when the generated output uses the given import path. See the gomock documentation on -imports for more information. |
|
self_package | string | The full import path for the generated code. See the gomock documentation on -self_package for more information. |
|
mock_names | string_dict | Dictionary of interface name to mock name pairs to change the output names of the mock objects. Mock names default to 'Mock' prepended to the name of the interface. See the gomock documentation on -mock_names for more information. |
|
copyright_file | Label | The file containing the copyright to prepend to the generated output. See the gomock documentation on -copyright_file for more information. |
|
aux_files | string_list_dict | A map from packages to auxilliary Go source files to load for those packages. Currently, assumes that the file (the value) is a path relative to the directory of library in the GOPATH. See the gomock documentation on -aux_files for more information. |