Allow to run cpp tests under grpc/tests/ using bazel. (#6040)

This is the first step to upgrade grpc dependency to the latest version.

- Patch protobuf 3.6.1. and grpc 1.15.1 to fix build errors when using the latest Bazel version (3.4.1).
- Add grpc/tests:grpc_test. One can kick off tests in Bazel by calling `bazel test grpc/tests/...`.
- Add missing build targets in tests/BUILD in order to support grpc/tests/BUILD

.gitignore

@@ -127,3 +127,4 @@ grpc/google/
 **/Package.resolved
 .clangd/**
 package-lock.json
+.clwb

BUILD

@@ -27,6 +27,7 @@ filegroup(
         "include/flatbuffers/code_generators.h",
         "include/flatbuffers/flatbuffers.h",
         "include/flatbuffers/flexbuffers.h",
+        "include/flatbuffers/grpc.h",
         "include/flatbuffers/hash.h",
         "include/flatbuffers/idl.h",
         "include/flatbuffers/minireflect.h",

WORKSPACE

@@ -4,27 +4,44 @@ load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
 http_archive(
     name = "io_bazel_rules_go",
+    sha256 = "e88471aea3a3a4f19ec1310a55ba94772d087e9ce46e41ae38ecebe17935de7b",
     urls = [
         "https://storage.googleapis.com/bazel-mirror/github.com/bazelbuild/rules_go/releases/download/v0.20.3/rules_go-v0.20.3.tar.gz",
         "https://github.com/bazelbuild/rules_go/releases/download/v0.20.3/rules_go-v0.20.3.tar.gz",
     ],
-    sha256 = "e88471aea3a3a4f19ec1310a55ba94772d087e9ce46e41ae38ecebe17935de7b",
 )
 
-load("@io_bazel_rules_go//go:deps.bzl", "go_rules_dependencies", "go_register_toolchains")
+load("@io_bazel_rules_go//go:deps.bzl", "go_register_toolchains", "go_rules_dependencies")
 
 go_rules_dependencies()
 
 go_register_toolchains()
 
+##### Protobuf
+_PROTOBUF_VERSION = "3.6.1"
+
+http_archive(
+    name = "com_google_protobuf",
+    patch_args = ["-p1"],
+    patches = [
+        "//bazel:protobuf_deps_3_6_1.patch",
+    ],
+    strip_prefix = "protobuf-" + _PROTOBUF_VERSION,
+    urls = [
+        "https://github.com/protocolbuffers/protobuf/archive/v" + _PROTOBUF_VERSION + ".tar.gz",
+    ],
+)
 
 ##### GRPC
 _GRPC_VERSION = "1.15.1"
 
 http_archive(
     name = "com_github_grpc_grpc",
-    patches = ["//bazel:grpc_deps_1_15_1.patch"],
     patch_args = ["-p1"],
+    patches = [
+        "//bazel:grpc_deps_1_15_1.patch",
+        "//bazel:grpc_deps_1_15_1_02.patch",
+    ],
     strip_prefix = "grpc-" + _GRPC_VERSION,
     urls = ["https://github.com/grpc/grpc/archive/v" + _GRPC_VERSION + ".tar.gz"],
 )

bazel/grpc_deps_1_15_1_02.patch

@@ -0,0 +1,48 @@
+diff --git a/bazel/cc_grpc_library.bzl b/bazel/cc_grpc_library.bzl
+index 3288565714..6bfcd653f5 100644
+--- a/bazel/cc_grpc_library.bzl
++++ b/bazel/cc_grpc_library.bzl
+@@ -1,6 +1,6 @@
+ """Generates and compiles C++ grpc stubs from proto_library rules."""
+ 
+-load("//:bazel/generate_cc.bzl", "generate_cc")
++load("//bazel:generate_cc.bzl", "generate_cc")
+ 
+ def cc_grpc_library(name, srcs, deps, proto_only, well_known_protos, generate_mocks = False, use_external = False, **kwargs):
+   """Generates C++ grpc classes from a .proto file.
+diff --git a/bazel/generate_cc.bzl b/bazel/generate_cc.bzl
+index ae747aa42c..2f14071f92 100644
+--- a/bazel/generate_cc.bzl
++++ b/bazel/generate_cc.bzl
+@@ -83,7 +83,7 @@ _generate_cc = rule(
+     attrs = {
+         "srcs": attr.label_list(
+             mandatory = True,
+-            non_empty = True,
++            allow_empty = False,
+             providers = ["proto"],
+         ),
+         "plugin": attr.label(
+diff --git a/bazel/grpc_build_system.bzl b/bazel/grpc_build_system.bzl
+index 73147bf3ac..e8c392aa93 100644
+--- a/bazel/grpc_build_system.bzl
++++ b/bazel/grpc_build_system.bzl
+@@ -24,6 +24,9 @@
+ #
+ 
+ # The set of pollers to test against if a test exercises polling
++
++load("//bazel:cc_grpc_library.bzl", "cc_grpc_library")
++
+ POLLERS = ['epollex', 'epollsig', 'epoll1', 'poll', 'poll-cv']
+ 
+ def if_not_windows(a):
+@@ -95,8 +98,6 @@ def grpc_proto_plugin(name, srcs = [], deps = []):
+     deps = deps,
+   )
+ 
+-load("//:bazel/cc_grpc_library.bzl", "cc_grpc_library")
+-
+ def grpc_proto_library(name, srcs = [], deps = [], well_known_protos = False,
+                        has_services = True, use_external = False, generate_mocks = False):
+   cc_grpc_library(

bazel/protobuf_deps_3_6_1.patch

@@ -0,0 +1,24 @@
+diff --git a/protobuf.bzl b/protobuf.bzl
+index 78f19c621..3b6d183b9 100644
+--- a/protobuf.bzl
++++ b/protobuf.bzl
+@@ -130,7 +130,7 @@ proto_gen = rule(
+         "protoc": attr.label(
+             cfg = "host",
+             executable = True,
+-            single_file = True,
++            allow_single_file = True,
+             mandatory = True,
+         ),
+         "plugin": attr.label(
+@@ -266,8 +266,8 @@ def internal_gen_well_known_protos_java(srcs):
+   Args:
+     srcs: the well known protos
+   """
+-  root = Label("%s//protobuf_java" % (REPOSITORY_NAME)).workspace_root
+-  pkg = PACKAGE_NAME + "/" if PACKAGE_NAME else ""
++  root = Label("%s//protobuf_java" % (native.repository_name())).workspace_root
++  pkg = native.package_name() + "/" if native.package_name() else ""
+   if root == "":
+     include = " -I%ssrc " % pkg
+   else:

grpc/README.md

@@ -22,6 +22,12 @@ the GRPC libraries for this to compile. This test will build using the
 5. `cmake -DFLATBUFFERS_BUILD_GRPCTEST=ON -DGRPC_INSTALL_PATH=${GRPC_INSTALL_PATH} -DPROTOBUF_DOWNLOAD_PATH=${PROTOBUF_DOWNLOAD_PATH} ..`
 6. `make`
 
+For Bazel users:
+
+```shell
+$bazel test src/compiler/...
+```
+
 ## Running FlatBuffer gRPC tests
 
 ### Linux
@@ -29,3 +35,9 @@ the GRPC libraries for this to compile. This test will build using the
 1. `ln -s ${GRPC_INSTALL_PATH}/lib/libgrpc++_unsecure.so.6 ${GRPC_INSTALL_PATH}/lib/libgrpc++_unsecure.so.1`
 2. `export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:${GRPC_INSTALL_PATH}/lib`
 3. `make test ARGS=-V` 
+
+For Bazel users:
+
+```shell
+$bazel test tests/...
+```

grpc/tests/BUILD

@@ -0,0 +1,17 @@
+cc_test(
+    name = "grpc_test",
+    srcs = [
+        "grpctest.cpp",
+        "message_builder_test.cpp",
+    ],
+    copts = ["-Itests"],
+    # This is required.
+    linkstatic = 1,
+    deps = [
+        "//tests:monster_test_cc_fbs",
+        "//tests:monster_test_grpc",
+        "//tests:test_assert",
+        "//tests:test_builder",
+        "@com_github_grpc_grpc//:grpc++",
+    ],
+)

src/BUILD

@@ -55,8 +55,8 @@ cc_library(
         "idl_gen_php.cpp",
         "idl_gen_python.cpp",
         "idl_gen_rust.cpp",
-        "idl_gen_text.cpp",
         "idl_gen_swift.cpp",
+        "idl_gen_text.cpp",
         "util.cpp",
     ],
     hdrs = [

tests/BUILD

@@ -9,6 +9,7 @@ cc_test(
     srcs = [
         "evolution_test/evolution_v1_generated.h",
         "evolution_test/evolution_v2_generated.h",
+        "monster_test_bfbs_generated.h",
         "namespace_test/namespace_test1_generated.h",
         "namespace_test/namespace_test2_generated.h",
         "native_type_test_impl.cpp",
@@ -19,7 +20,6 @@ cc_test(
         "test_builder.cpp",
         "test_builder.h",
         "union_vector/union_vector_generated.h",
-        "monster_test_bfbs_generated.h",
     ],
     copts = [
         "-DFLATBUFFERS_TRACK_VERIFIER_BUFFER_SIZE",
@@ -70,6 +70,45 @@ cc_test(
 # Test bzl rules
 load("//:build_defs.bzl", "flatbuffer_cc_library")
 
+cc_library(
+    name = "test_assert",
+    srcs = ["test_assert.cpp"],
+    hdrs = ["test_assert.h"],
+    visibility = ["//grpc/tests:__subpackages__"],
+    deps = ["//:flatbuffers"],
+)
+
+cc_library(
+    name = "test_builder",
+    srcs = ["test_builder.cpp"],
+    hdrs = ["test_builder.h"],
+    visibility = ["//grpc/tests:__subpackages__"],
+    deps = [
+        ":monster_test_grpc",
+        ":test_assert",
+        "//:flatbuffers",
+    ],
+)
+
+cc_library(
+    name = "monster_test_grpc",
+    srcs = [
+        "monster_test.grpc.fb.cc",
+        "monster_test.grpc.fb.h",
+        "monster_test_generated.h",
+    ],
+    hdrs = [
+        "monster_test.grpc.fb.h",
+        "monster_test_generated.h",
+    ],
+    includes = ["."],
+    visibility = ["//grpc/tests:__subpackages__"],
+    deps = [
+        "//:flatbuffers",
+        "@com_github_grpc_grpc//:grpc++",
+    ],
+)
+
 flatbuffer_cc_library(
     name = "monster_test_cc_fbs",
     srcs = ["monster_test.fbs"],
@@ -78,6 +117,7 @@ flatbuffer_cc_library(
         "include_test/include_test1.fbs",
         "include_test/sub/include_test2.fbs",
     ],
+    visibility = ["//grpc/tests:__subpackages__"],
 )
 
 flatbuffer_cc_library(