[ggj][infra][2/5] feat: bazel rules support for integration test

[xiaozhenliu-gg5]

Find more details in design doc: go/java-micro-integration-test-infra

Support bazel rules to run integration test against Redis API, which includes 1) code generation by micro-generator 2) compare codegen with goldens in test/integration/goldens/redis.

Run the below command to trigger the integration test, and the test failure (diff between codegen and goldens) can be found directly in test.log

bazel test //test/integration:redis

FAIL: //test/integration:redis (see /usr/local/google/home/xiaozhenliu/.cache/bazel/_bazel_xiaozhenliu/96b19089c047889e0621b0e06e850da1/execroot/gapic_generator_java/bazel-out/k8-fastbuild/testlogs/test/integration/redis/test.log)
Target //test/integration:redis up-to-date:
  bazel-bin/test/integration/diff_output.txt
  bazel-bin/test/integration/check_diff_script.sh
INFO: Elapsed time: 155.658s, Critical Path: 64.83s
INFO: 487 processes: 35 internal, 375 linux-sandbox, 77 worker.
INFO: Build completed, 1 test FAILED, 487 total actions
//test/integration:redis                                                 FAILED in 0.1s
  /usr/local/google/home/xiaozhenliu/.cache/bazel/_bazel_xiaozhenliu/96b19089c047889e0621b0e06e850da1/execroot/gapic_generator_java/bazel-out/k8-fastbuild/testlogs/test/integration/redis/test.log



============= test.log ===============
exec ${PAGER:-/usr/bin/less} "$0" || exit 1
Executing tests from //test/integration:redis
-----------------------------------------------------------------------------
diff codegen_tmp/CloudRedisClient.java test/integration/goldens/redis/CloudRedisClient.java
17,18d16
< package com.google.cloud.redis.v1;
<

[xiaozhenliu-gg5]

When the BUILD_WORKSPACE_DIRECTORY env variable is not present, in which context do you run your command: bazel build, bazel run, bazel test? I believe BUILD_WORKSPACE_DIRECTORY is there only for bazel run.

we use bazel test //test/integration: redis to trigger the integration test of Redis API. More info is in description. Thanks! @vam-google If BUILD_WORKSPACE_DIRECTORY is only for bazel run, then is there an equivalent env that can enable us to have access to the generated diff_output folder?