Add integration test for python coverage.

src/test/shell/bazel/BUILD

@@ -514,6 +514,15 @@ sh_test(
     ],
 )
 
+sh_test(
+    name = "bazel_coverage_hermetic_py_test",
+    srcs = ["bazel_coverage_hermetic_py_test.sh"],
+    data = [":test-deps"],
+    tags = [
+        "no_windows",
+    ],
+)
+
 sh_test(
     name = "bazel_coverage_sh_test",
     srcs = ["bazel_coverage_sh_test.sh"],

src/test/shell/bazel/bazel_coverage_hermetic_py_test.sh

@@ -0,0 +1,183 @@
+#!/bin/bash
+#
+# Copyright 2015 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -eu
+
+# Load the test setup defined in the parent directory
+CURRENT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "${CURRENT_DIR}/../integration_test_setup.sh" \
+  || { echo "integration_test_setup.sh not found!" >&2; exit 1; }
+
+# Fetch hermetic python and register toolchain.
+function set_up() {
+    cat >>WORKSPACE <<EOF
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+http_archive(
+    name = "rules_python",
+    sha256 = "cdf6b84084aad8f10bf20b46b77cb48d83c319ebe6458a18e9d2cebf57807cdd",
+    strip_prefix = "rules_python-0.8.1",
+    url = "https://github.com/bazelbuild/rules_python/archive/refs/tags/0.8.1.tar.gz",
+)
+
+load("@rules_python//python:repositories.bzl", "python_register_toolchains")
+
+# Load hermetic python toolchain.
+python_register_toolchains(
+    name = "python3_9",
+    python_version = "3.9",
+    # Don't register it, though, because we need to set up coverage support.
+    register_toolchains = False,
+)
+
+http_archive(
+    name = "coverage_linux_x64",
+    build_file_content = """
+filegroup(
+    name = "coverage",
+    srcs = ["coverage/__main__.py"],
+    data = glob(["coverage/*", "coverage/**/*.py"]),
+    visibility = ["//visibility:public"],
+)
+""",
+    sha256 = "84631e81dd053e8a0d4967cedab6db94345f1c36107c71698f746cb2636c63e3",
+    type = "zip",
+    urls = [
+        "https://files.pythonhosted.org/packages/74/0d/0f3c522312fd27c32e1abe2fb5c323b583a5c108daf2c26d6e8dfdd5a105/coverage-6.4.1-cp39-cp39-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_17_x86_64.manylinux2014_x86_64.whl",
+    ],
+)
+
+register_toolchains(
+    "//:python_toolchain",
+)
+EOF
+}
+
+# Asserts if the given expected coverage result is included in the given output
+# file.
+#
+# - expected_coverage The expected result that must be included in the output.
+# - output_file       The location of the coverage output file.
+function assert_coverage_result() {
+    local expected_coverage="${1}"; shift
+    local output_file="${1}"; shift
+
+    # Replace newlines with commas to facilitate the assertion.
+    local expected_coverage_no_newlines="$( echo "$expected_coverage" | tr '\n' ',' )"
+    local output_file_no_newlines="$( cat "$output_file" | tr '\n' ',' )"
+
+    (echo "$output_file_no_newlines" \
+        | grep -F "$expected_coverage_no_newlines") \
+        || fail "Expected coverage result
+<$expected_coverage>
+was not found in actual coverage report:
+<$( cat "$output_file" )>"
+}
+
+# Returns the path of the code coverage report that was generated by Bazel by
+# looking at the current $TEST_log. The method fails if TEST_log does not
+# contain any coverage report for a passed test.
+function get_coverage_file_path_from_test_log() {
+  local ending_part="$(sed -n -e '/PASSED/,$p' "$TEST_log")"
+
+  local coverage_file_path=$(grep -Eo "/[/a-zA-Z0-9\.\_\-]+\.dat$" <<< "$ending_part")
+  [[ -e "$coverage_file_path" ]] || fail "Coverage output file does not exist!"
+  echo "$coverage_file_path"
+}
+
+function set_up_py_test_coverage() {
+  # Set up python toolchain.
+  cat <<EOF > BUILD
+load("@bazel_tools//tools/python:toolchain.bzl", "py_runtime_pair")
+
+py_runtime(
+    name = "py3_runtime",
+    coverage_tool = "@coverage_linux_x64//:coverage",
+    files = ["@python3_9_x86_64-unknown-linux-gnu//:files"],
+    interpreter = "@python3_9_x86_64-unknown-linux-gnu//:bin/python3",
+    python_version = "PY3",
+)
+
+py_runtime_pair(
+    name = "python_runtimes",
+    py2_runtime = None,
+    py3_runtime = ":py3_runtime",
+)
+
+toolchain(
+    name = "python_toolchain",
+    exec_compatible_with = [
+        "@platforms//os:linux",
+        "@platforms//cpu:x86_64",
+    ],
+    toolchain = ":python_runtimes",
+    toolchain_type = "@bazel_tools//tools/python:toolchain_type",
+)
+EOF
+  # Add a py_library and test.
+  cat <<EOF >> BUILD
+py_library(
+    name = "hello",
+    srcs = ["hello.py"],
+)
+
+py_test(
+    name = "hello_test",
+    srcs = ["hello_test.py"],
+    deps = [":hello"],
+)
+EOF
+  cat <<EOF > hello.py
+def Hello():
+  print("Hello, world!")
+
+def Goodbye():
+  print("Goodbye, world!")
+EOF
+  cat <<EOF > hello_test.py
+import unittest
+import hello
+
+class Tests(unittest.TestCase):
+  def testHello(self):
+    hello.Hello()
+
+if __name__ == "__main__":
+  unittest.main()
+EOF
+  cat <<EOF > expected.dat
+SF:hello.py
+FNF:0
+FNH:0
+DA:1,1,fi+A0ud2xABMExsbhdW38w
+DA:2,1,3qA2I6CcUyJmcd1vpeVcRA
+DA:4,1,nFnrj5CwYCqkvbVhPUFVVw
+DA:5,0,RmWioilSA3bI5NbLlwiuSA
+LH:3
+LF:4
+end_of_record
+EOF
+}
+
+function test_py_test_coverage() {
+  set_up_py_test_coverage
+  bazel coverage --test_output=all //:hello_test &>$TEST_log || fail "Coverage for //:hello_test failed"
+  local coverage_file_path="$( get_coverage_file_path_from_test_log )"
+  diff expected.dat "$coverage_file_path" >> $TEST_log
+  cmp expected.dat "$coverage_file_path" || fail "Coverage output file is different than the expected file for py_library."
+}
+
+run_suite "test tests"