Unable to generate client if it has a proto-plus dependency with a modified namespace

[ohmayr]

The test //google/cloud/policytroubleshooter/iam/v3:iam_py_gapic_test is failing once I add google.iam.v2 as a proto-plus dependency.

Steps to reproduce the issue:

• Update the google/cloud/policytroubleshooter/iam/v3/BUILD.bazel file with the following code:

load(
    "@com_google_googleapis_imports//:imports.bzl",
    "py_gapic_assembly_pkg",
    "py_gapic_library",
    "py_import",
    "py_test"
)

py_import(
    name="iam_v2",
    srcs = [
        "//google/iam/v2:iam_py_gapic",
    ],
)

py_gapic_library(
    name = "iam_py_gapic",
    srcs = [":iam_proto"],
    grpc_service_config = "policytroubleshooter_v3_grpc_service_config.json",
    rest_numeric_enums = True,
    service_yaml = "policytroubleshooter_v3.yaml",
    transport = "grpc+rest",
    deps = [
        ":iam_v2",
        "//google/iam/v1:iam_policy_py_proto",
    ],
    opt_args = [
        "python-gapic-namespace=google.cloud",
        "python-gapic-name=policytroubleshooter_iam",
        "proto-plus-deps=google.iam.v2"
    ],
)

Run the test:

bazel run //google/cloud/policytroubleshooter/iam/v3:iam_py_gapic_test

Error message:

==================================== ERRORS ====================================
_ ERROR collecting tests/unit/gapic/policytroubleshooter_iam_v3/test_policy_troubleshooter.py _
ImportError while importing test module '/usr/local/google/home/omairn/.cache/bazel/_bazel_omairn/9febfd2a38daa3aed258879a45f94c15/execroot/com_google_googleapis/bazel-out/k8-fastbuild/bin/google/cloud/policytroubleshooter/iam/v3/iam_py_gapic_test.runfiles/com_google_googleapis/google/cloud/policytroubleshooter/iam/v3/iam_py_gapic_srcjar.py/tests/unit/gapic/policytroubleshooter_iam_v3/test_policy_troubleshooter.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
../../../../../../../../../../../../external/python39_x86_64-unknown-linux-gnu/lib/python3.9/importlib/__init__.py:127: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
google/cloud/policytroubleshooter/iam/v3/iam_py_gapic_srcjar.py/tests/unit/gapic/policytroubleshooter_iam_v3/test_policy_troubleshooter.py:46: in <module>
    from google.cloud.policytroubleshooter_iam_v3.services.policy_troubleshooter import PolicyTroubleshooterAsyncClient
google/cloud/policytroubleshooter/iam/v3/iam_py_gapic_srcjar.py/google/cloud/policytroubleshooter_iam_v3/__init__.py:21: in <module>
    from .services.policy_troubleshooter import PolicyTroubleshooterClient
google/cloud/policytroubleshooter/iam/v3/iam_py_gapic_srcjar.py/google/cloud/policytroubleshooter_iam_v3/services/policy_troubleshooter/__init__.py:16: in <module>
    from .client import PolicyTroubleshooterClient
google/cloud/policytroubleshooter/iam/v3/iam_py_gapic_srcjar.py/google/cloud/policytroubleshooter_iam_v3/services/policy_troubleshooter/client.py:38: in <module>
    from google.cloud.policytroubleshooter_iam_v3.types import troubleshooter
google/cloud/policytroubleshooter/iam/v3/iam_py_gapic_srcjar.py/google/cloud/policytroubleshooter_iam_v3/types/__init__.py:16: in <module>
    from .troubleshooter import (
google/cloud/policytroubleshooter/iam/v3/iam_py_gapic_srcjar.py/google/cloud/policytroubleshooter_iam_v3/types/troubleshooter.py:23: in <module>
    from google.iam_v2.types import policy as giv_policy
E   ModuleNotFoundError: No module named 'google.iam_v2'
=========================== short test summary info ============================
ERROR google/cloud/policytroubleshooter/iam/v3/iam_py_gapic_srcjar.py/tests/unit/gapic/policytroubleshooter_iam_v3/test_policy_troubleshooter.py
!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!
8 warnings, 1 error in 1.57s

It seems like the test is complaining about the missing module google.iam_v2 which is correct. We need to investigate why the generator is not looking for the correct namespace mentioned in google/iam/v2/BUILD.bazel i.e. "python-gapic-namespace=google.cloud" and the module that it needs to look for should be google.cloud.iam_v2.