#!/bin/bash
#
# Copyright 2018 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.

# Test Python 2/3 version behavior. These tests require that the target platform
# has both Python versions available.

# --- begin runfiles.bash initialization ---
# Copy-pasted from Bazel's Bash runfiles library (tools/bash/runfiles/runfiles.bash).
set -euo pipefail
if [[ ! -d "${RUNFILES_DIR:-/dev/null}" && ! -f "${RUNFILES_MANIFEST_FILE:-/dev/null}" ]]; then
  if [[ -f "$0.runfiles_manifest" ]]; then
    export RUNFILES_MANIFEST_FILE="$0.runfiles_manifest"
  elif [[ -f "$0.runfiles/MANIFEST" ]]; then
    export RUNFILES_MANIFEST_FILE="$0.runfiles/MANIFEST"
  elif [[ -f "$0.runfiles/bazel_tools/tools/bash/runfiles/runfiles.bash" ]]; then
    export RUNFILES_DIR="$0.runfiles"
  fi
fi
if [[ -f "${RUNFILES_DIR:-/dev/null}/bazel_tools/tools/bash/runfiles/runfiles.bash" ]]; then
  source "${RUNFILES_DIR}/bazel_tools/tools/bash/runfiles/runfiles.bash"
elif [[ -f "${RUNFILES_MANIFEST_FILE:-/dev/null}" ]]; then
  source "$(grep -m1 "^bazel_tools/tools/bash/runfiles/runfiles.bash " \
            "$RUNFILES_MANIFEST_FILE" | cut -d ' ' -f 2-)"
else
  echo >&2 "ERROR: cannot find @bazel_tools//tools/bash/runfiles:runfiles.bash"
  exit 1
fi
# --- end runfiles.bash initialization ---

source "$(rlocation "io_bazel/src/test/shell/integration_test_setup.sh")" \
  || { echo "integration_test_setup.sh not found!" >&2; exit 1; }

# `uname` returns the current platform, e.g "MSYS_NT-10.0" or "Linux".
# `tr` converts all upper case letters to lower case.
# `case` matches the result if the `uname | tr` expression to string prefixes
# that use the same wildcards as names do in Bash, i.e. "msys*" matches strings
# starting with "msys", and "*" matches everything (it's the default case).
case "$(uname -s | tr [:upper:] [:lower:])" in
msys*)
  # As of 2018-08-14, Bazel on Windows only supports MSYS Bash.
  declare -r is_windows=true
  ;;
*)
  declare -r is_windows=false
  ;;
esac

if "$is_windows"; then
  # Disable MSYS path conversion that converts path-looking command arguments to
  # Windows paths (even if they arguments are not in fact paths).
  export MSYS_NO_PATHCONV=1
  export MSYS2_ARG_CONV_EXCL="*"
fi

#### TESTS #############################################################

# Sanity test that our environment setup works.
function test_can_run_py_binaries() {
  mkdir -p test

  cat > test/BUILD << EOF
py_binary(
    name = "main2",
    python_version = "PY2",
    srcs = ['main2.py'],
)
py_binary(
    name = "main3",
    python_version = "PY3",
    srcs = ["main3.py"],
)
EOF

  cat > test/main2.py << EOF
import platform
print("I am Python " + platform.python_version_tuple()[0])
EOF
  cp test/main2.py test/main3.py

  bazel run //test:main2 \
      &> $TEST_log || fail "bazel run failed"
  expect_log "I am Python 2"

  bazel run //test:main3 \
      &> $TEST_log || fail "bazel run failed"
  expect_log "I am Python 3"
}

# Test that access to runfiles works (in general, and under our test environment
# specifically).
function test_can_access_runfiles() {
  mkdir -p test

  cat > test/BUILD << EOF
py_binary(
  name = "main",
  srcs = ["main.py"],
  deps = ["@bazel_tools//tools/python/runfiles"],
  data = ["data.txt"],
)
EOF

  cat > test/data.txt << EOF
abcdefg
EOF

  cat > test/main.py << EOF
from bazel_tools.tools.python.runfiles import runfiles

r = runfiles.Create()
path = r.Rlocation("$WORKSPACE_NAME/test/data.txt")
print("Rlocation returned: " + str(path))
if path is not None:
  with open(path, 'rt') as f:
    print("File contents: " + f.read())
EOF
  chmod u+x test/main.py

  bazel build //test:main || fail "bazel build failed"
  MAIN_BIN=$(bazel info bazel-bin)/test/main
  RUNFILES_MANIFEST_FILE= RUNFILES_DIR= $MAIN_BIN &> $TEST_log
  expect_log "File contents: abcdefg"
}

# Regression test for #5104. This test ensures that it's possible to use
# --build_python_zip in combination with an in-workspace runtime, as opposed to
# with a system runtime or not using a py_runtime at all (the legacy
# --python_path mechanism).
#
# The specific issue #5104 was caused by file permissions being lost when
# unzipping runfiles, which led to an unexecutable runtime.
function test_build_python_zip_works_with_workspace_runtime() {
  mkdir -p test

  # The runfiles interpreter is either a sh script or bat script depending on
  # the current platform.
  if "$is_windows"; then
    INTERPRETER_FILE="mockpy.bat"
  else
    INTERPRETER_FILE="mockpy.sh"
  fi

  cat > test/BUILD << EOF
load("@bazel_tools//tools/python:toolchain.bzl", "py_runtime_pair")

py_binary(
    name = "pybin",
    srcs = ["pybin.py"],
)

py_runtime(
    name = "mock_runtime",
    interpreter = ":$INTERPRETER_FILE",
    python_version = "PY3",
)

py_runtime_pair(
    name = "mock_runtime_pair",
    py3_runtime = ":mock_runtime",
)

toolchain(
    name = "mock_toolchain",
    toolchain = ":mock_runtime_pair",
    toolchain_type = "@bazel_tools//tools/python:toolchain_type",
)
EOF
  cat > test/pybin.py << EOF
# This doesn't actually run because we use a mock Python runtime that never
# executes the Python code.
print("I am pybin!")
EOF
  if "$is_windows"; then
    cat > "test/$INTERPRETER_FILE" << EOF
@ECHO I am mockpy!
EOF
  else
    cat > "test/$INTERPRETER_FILE" << EOF
#!/bin/sh
echo "I am mockpy!"
EOF
    chmod u+x test/mockpy.sh
  fi

  bazel run //test:pybin \
      --extra_toolchains=//test:mock_toolchain --build_python_zip \
      &> $TEST_log || fail "bazel run failed"
  expect_log "I am mockpy!"
}

function test_get_python_zip_file_via_output_group() {
  touch foo.py
  cat > BUILD <<'EOF'
py_binary(
  name = 'foo',
  srcs = ['foo.py'],
)
EOF
  bazel build :foo --build_python_zip=false --output_groups=python_zip_file \
      &> $TEST_log || fail "bazel build failed"
  [[ -f "bazel-bin/foo.zip" ]] || fail "failed to build python zip file via output group"
}

function test_pybin_can_have_different_version_pybin_as_data_dep() {
  # TODO(#8503): Fix this test for windows.
  if "$is_windows"; then
    return
  fi

  mkdir -p test

  cat > test/BUILD << EOF
py_binary(
  name = "py2bin",
  srcs = ["py2bin.py"],
  python_version = "PY2",
)
py_binary(
  name = "py3bin",
  srcs = ["py3bin.py"],
  python_version = "PY3",
)
py_binary(
  name = "py2bin_calling_py3bin",
  srcs = ["py2bin_calling_py3bin.py"],
  deps = ["@bazel_tools//tools/python/runfiles"],
  data = [":py3bin"],
  python_version = "PY2",
)
py_binary(
  name = "py3bin_calling_py2bin",
  srcs = ["py3bin_calling_py2bin.py"],
  deps = ["@bazel_tools//tools/python/runfiles"],
  data = [":py2bin"],
  python_version = "PY3",
)
EOF

  cat > test/py2bin.py << EOF
import platform

print("Inner bin uses Python " + platform.python_version_tuple()[0])
EOF
  cp test/py2bin.py test/py3bin.py

  cat > test/py2bin_calling_py3bin.py << EOF
import platform
import subprocess
from bazel_tools.tools.python.runfiles import runfiles

print("Outer bin uses Python " + platform.python_version_tuple()[0])

r = runfiles.Create()
bin_path = r.Rlocation("$WORKSPACE_NAME/test/py3bin")
assert bin_path is not None

subprocess.call([bin_path])
EOF
  sed s/py3bin/py2bin/ test/py2bin_calling_py3bin.py > test/py3bin_calling_py2bin.py

  EXPFLAG="--incompatible_allow_python_version_transitions=true \
--incompatible_py3_is_default=false \
--incompatible_py2_outputs_are_suffixed=false"

  bazel build $EXPFLAG //test:py2bin_calling_py3bin //test:py3bin_calling_py2bin \
      || fail "bazel build failed"
  PY2_OUTER_BIN=$(bazel info bazel-bin $EXPFLAG)/test/py2bin_calling_py3bin
  PY3_OUTER_BIN=$(bazel info bazel-bin $EXPFLAG --python_version=PY3)/test/py3bin_calling_py2bin

  RUNFILES_MANIFEST_FILE= RUNFILES_DIR= $PY2_OUTER_BIN &> $TEST_log
  expect_log "Outer bin uses Python 2"
  expect_log "Inner bin uses Python 3"

  RUNFILES_MANIFEST_FILE= RUNFILES_DIR= $PY3_OUTER_BIN &> $TEST_log
  expect_log "Outer bin uses Python 3"
  expect_log "Inner bin uses Python 2"
}

function test_shbin_can_have_different_version_pybins_as_data_deps() {
  # Uses bash, disable on windows.
  if "$is_windows"; then
    return
  fi

  mkdir -p test

  cat > test/BUILD << EOF
py_binary(
  name = "py2bin",
  srcs = ["py2bin.py"],
  python_version = "PY2",
)
py_binary(
  name = "py3bin",
  srcs = ["py3bin.py"],
  python_version = "PY3",
)
sh_binary(
  name = "shbin_calling_py23bins",
  srcs = ["shbin_calling_py23bins.sh"],
  deps = ["@bazel_tools//tools/bash/runfiles"],
  data = [":py2bin", ":py3bin"],
)
EOF

  cat > test/py2bin.py << EOF
import platform

print("py2bin uses Python " + platform.python_version_tuple()[0])
EOF
  sed s/py2bin/py3bin/ test/py2bin.py > test/py3bin.py
  chmod u+x test/py2bin.py test/py3bin.py

  # The workspace name is initialized in testenv.sh; use that var rather than
  # hardcoding it here. The extra sed pass is so we can selectively expand that
  # one var while keeping the rest of the heredoc literal.
  cat | sed "s/{{WORKSPACE_NAME}}/$WORKSPACE_NAME/" > test/shbin_calling_py23bins.sh << 'EOF'
# --- begin runfiles.bash initialization ---
# Copy-pasted from Bazel's Bash runfiles library (tools/bash/runfiles/runfiles.bash).
set -euo pipefail
if [[ ! -d "${RUNFILES_DIR:-/dev/null}" && ! -f "${RUNFILES_MANIFEST_FILE:-/dev/null}" ]]; then
  if [[ -f "$0.runfiles_manifest" ]]; then
    export RUNFILES_MANIFEST_FILE="$0.runfiles_manifest"
  elif [[ -f "$0.runfiles/MANIFEST" ]]; then
    export RUNFILES_MANIFEST_FILE="$0.runfiles/MANIFEST"
  elif [[ -f "$0.runfiles/bazel_tools/tools/bash/runfiles/runfiles.bash" ]]; then
    export RUNFILES_DIR="$0.runfiles"
  fi
fi
if [[ -f "${RUNFILES_DIR:-/dev/null}/bazel_tools/tools/bash/runfiles/runfiles.bash" ]]; then
  source "${RUNFILES_DIR}/bazel_tools/tools/bash/runfiles/runfiles.bash"
elif [[ -f "${RUNFILES_MANIFEST_FILE:-/dev/null}" ]]; then
  source "$(grep -m1 "^bazel_tools/tools/bash/runfiles/runfiles.bash " \
            "$RUNFILES_MANIFEST_FILE" | cut -d ' ' -f 2-)"
else
  echo >&2 "ERROR: cannot find @bazel_tools//tools/bash/runfiles:runfiles.bash"
  exit 1
fi
# --- end runfiles.bash initialization ---

$(rlocation {{WORKSPACE_NAME}}/test/py2bin)
$(rlocation {{WORKSPACE_NAME}}/test/py3bin)
EOF

  chmod u+x test/shbin_calling_py23bins.sh

  EXPFLAG="--incompatible_allow_python_version_transitions=true \
--incompatible_py3_is_default=false \
--incompatible_py2_outputs_are_suffixed=false"

  bazel build $EXPFLAG //test:shbin_calling_py23bins \
      || fail "bazel build failed"
  SH_BIN=$(bazel info bazel-bin $EXPFLAG)/test/shbin_calling_py23bins

  RUNFILES_MANIFEST_FILE= RUNFILES_DIR= $SH_BIN &> $TEST_log
  expect_log "py2bin uses Python 2"
  expect_log "py3bin uses Python 3"
}

function test_genrule_can_have_different_version_pybins_as_tools() {
  # This test currently checks that we can use --host_force_python to get
  # PY2 and PY3 binaries in tools. In the future we'll support both modes in the
  # same build without a flag (#6443).

  mkdir -p test

  cat > test/BUILD << 'EOF'
py_binary(
  name = "pybin",
  srcs = ["pybin.py"],
)
genrule(
  name = "genrule_calling_pybin",
  outs = ["out.txt"],
  tools = [":pybin"],
  cmd = "$(location :pybin) > $(location out.txt)"
)
EOF

  cat > test/pybin.py << EOF
import platform

print("pybin uses Python " + platform.python_version_tuple()[0])
EOF
  chmod u+x test/pybin.py

  # Run under both old and new semantics.
  for EXPFLAG in \
      "--incompatible_allow_python_version_transitions=true \
--incompatible_py3_is_default=false \
--incompatible_py2_outputs_are_suffixed=false" \
      "--incompatible_allow_python_version_transitions=false \
--incompatible_py3_is_default=false \
--incompatible_py2_outputs_are_suffixed=false"; do
    echo "Using $EXPFLAG" > $TEST_log
    bazel build $EXPFLAG --host_force_python=PY2 //test:genrule_calling_pybin \
        || fail "bazel build failed"
    ARTIFACT=$(bazel info bazel-genfiles $EXPFLAG)/test/out.txt
    cat $ARTIFACT > $TEST_log
    expect_log "pybin uses Python 2"

    echo "Using $EXPFLAG" > $TEST_log
    bazel build $EXPFLAG --host_force_python=PY3 //test:genrule_calling_pybin \
          || fail "bazel build failed"
      ARTIFACT=$(bazel info bazel-genfiles $EXPFLAG)/test/out.txt
      cat $ARTIFACT > $TEST_log
      expect_log "pybin uses Python 3"
  done
}

function test_can_build_same_target_for_both_versions_in_one_build() {
  # Uses bash, disable on windows.
  if "$is_windows"; then
    return
  fi

  mkdir -p test

  cat > test/BUILD << EOF
py_library(
  name = "common",
  srcs = ["common.py"],
)
py_binary(
  name = "py2bin",
  srcs = ["py2bin.py"],
  deps = [":common"],
  python_version = "PY2",
)
py_binary(
  name = "py3bin",
  srcs = ["py3bin.py"],
  deps = [":common"],
  python_version = "PY3",
)
sh_binary(
  name = "shbin",
  srcs = ["shbin.sh"],
  deps = ["@bazel_tools//tools/bash/runfiles"],
  data = [":py2bin", ":py3bin"],
)
EOF

  cat > test/common.py << EOF
import platform

print("common using Python " + platform.python_version_tuple()[0])
EOF

  cat > test/py2bin.py << EOF
import common
EOF
  chmod u+x test/py2bin.py
  cp test/py2bin.py test/py3bin.py

  # The workspace name is initialized in testenv.sh; use that var rather than
  # hardcoding it here. The extra sed pass is so we can selectively expand that
  # one var while keeping the rest of the heredoc literal.
  cat | sed "s/{{WORKSPACE_NAME}}/$WORKSPACE_NAME/" > test/shbin.sh << 'EOF'
# --- begin runfiles.bash initialization ---
# Copy-pasted from Bazel's Bash runfiles library (tools/bash/runfiles/runfiles.bash).
set -euo pipefail
if [[ ! -d "${RUNFILES_DIR:-/dev/null}" && ! -f "${RUNFILES_MANIFEST_FILE:-/dev/null}" ]]; then
  if [[ -f "$0.runfiles_manifest" ]]; then
    export RUNFILES_MANIFEST_FILE="$0.runfiles_manifest"
  elif [[ -f "$0.runfiles/MANIFEST" ]]; then
    export RUNFILES_MANIFEST_FILE="$0.runfiles/MANIFEST"
  elif [[ -f "$0.runfiles/bazel_tools/tools/bash/runfiles/runfiles.bash" ]]; then
    export RUNFILES_DIR="$0.runfiles"
  fi
fi
if [[ -f "${RUNFILES_DIR:-/dev/null}/bazel_tools/tools/bash/runfiles/runfiles.bash" ]]; then
  source "${RUNFILES_DIR}/bazel_tools/tools/bash/runfiles/runfiles.bash"
elif [[ -f "${RUNFILES_MANIFEST_FILE:-/dev/null}" ]]; then
  source "$(grep -m1 "^bazel_tools/tools/bash/runfiles/runfiles.bash " \
            "$RUNFILES_MANIFEST_FILE" | cut -d ' ' -f 2-)"
else
  echo >&2 "ERROR: cannot find @bazel_tools//tools/bash/runfiles:runfiles.bash"
  exit 1
fi
# --- end runfiles.bash initialization ---

$(rlocation {{WORKSPACE_NAME}}/test/py2bin)
$(rlocation {{WORKSPACE_NAME}}/test/py3bin)
EOF
  chmod u+x test/shbin.sh

  EXPFLAG="--incompatible_allow_python_version_transitions=true \
--incompatible_py3_is_default=false \
--incompatible_py2_outputs_are_suffixed=false"

  bazel build $EXPFLAG //test:shbin \
      || fail "bazel build failed"
  SH_BIN=$(bazel info bazel-bin)/test/shbin

  RUNFILES_MANIFEST_FILE= RUNFILES_DIR= $SH_BIN &> $TEST_log
  expect_log "common using Python 2"
  expect_log "common using Python 3"
}

# TODO(brandjon): Rename this file to python_test.sh or else move the below to
# a separate suite.

# Tests that a non-standard library module on the PYTHONPATH added by Bazel
# can override the standard library. This behavior is not necessarily ideal, but
# it is the current semantics; see #6532 about changing that.
function test_source_file_does_not_override_standard_library() {
  mkdir -p test

  cat > test/BUILD << EOF
py_binary(
    name = "main",
    srcs = ["main.py"],
    deps = [":lib"],
    # Pass the empty string, to include the path to this package (within
    # runfiles) on the PYTHONPATH.
    imports = [""],
)

py_library(
    name = "lib",
    # A src name that clashes with a standard library module, such that this
    # local file can take precedence over the standard one depending on its
    # order in PYTHONPATH. Not just any module name would work. For instance,
    # "import sys" gets the built-in module regardless of whether there's some
    # "sys.py" file on the PYTHONPATH. This is probably because built-in modules
    # (i.e., those implemented in C) use a different loader than
    # Python-implemented ones, even though they're both part of the standard
    # distribution of the interpreter.
    srcs = ["re.py"],
)
EOF
  cat > test/main.py << EOF
import re
EOF
  cat > test/re.py << EOF
print("I am lib!")
EOF

  bazel run //test:main \
      &> $TEST_log || fail "bazel run failed"
  # Indicates that the local module overrode the system one.
  expect_log "I am lib!"
}

# Tests that targets appear under the expected roots.
function test_output_roots() {
  # It's hard to get build output paths reliably, so we'll just check the output
  # of bazel info.

  # Legacy behavior, PY2 case.
  bazel info bazel-bin \
      --incompatible_py2_outputs_are_suffixed=false --python_version=PY2 \
      &> $TEST_log || fail "bazel info failed"
  expect_log "bazel-out/.*/bin"
  expect_not_log "bazel-out/.*-py2.*/bin"

  # Legacy behavior, PY3 case.
  bazel info bazel-bin \
      --incompatible_py2_outputs_are_suffixed=false --python_version=PY3 \
      &> $TEST_log || fail "bazel info failed"
  expect_log "bazel-out/.*-py3.*/bin"

  # New behavior, PY2 case.
  bazel info bazel-bin \
      --incompatible_py2_outputs_are_suffixed=true --python_version=PY2 \
      &> $TEST_log || fail "bazel info failed"
  expect_log "bazel-out/.*-py2.*/bin"

  # New behavior, PY3 case.
  bazel info bazel-bin \
      --incompatible_py2_outputs_are_suffixed=true --python_version=PY3 \
      &> $TEST_log || fail "bazel info failed"
  expect_log "bazel-out/.*/bin"
  expect_not_log "bazel-out/.*-py3.*/bin"
}

# Tests that bazel-bin points to where targets get built by default (or at least
# not to a directory with a -py2 or -py3 suffix), provided that
# --incompatible_py3_is_default and --incompatible_py2_outputs_are_suffixed are
# flipped together.
function test_default_output_root_is_bazel_bin() {
  bazel info bazel-bin \
      --incompatible_py3_is_default=false \
      --incompatible_py2_outputs_are_suffixed=false \
      &> $TEST_log || fail "bazel info failed"
  expect_log "bazel-out/.*/bin"
  expect_not_log "bazel-out/.*-py2.*/bin"
  expect_not_log "bazel-out/.*-py3.*/bin"

  bazel info bazel-bin \
      --incompatible_py3_is_default=true \
      --incompatible_py2_outputs_are_suffixed=true \
      &> $TEST_log || fail "bazel info failed"
  expect_log "bazel-out/.*/bin"
  expect_not_log "bazel-out/.*-py2.*/bin"
  expect_not_log "bazel-out/.*-py3.*/bin"
}

# Tests that we get a warning when host tools fail due to being built for the
# wrong Python version. See #7899 and #8549 for context, as well as
# {@link PyCommon#shouldWarnAboutHostVersionUponFailure}.
# TODO(#6443): Delete this once we no longer have the host configuration.
function test_host_version_mismatch_warning() {
  mkdir -p test

  cat > test/BUILD << 'EOF'
py_binary(
    name = "passing_tool_using_py2_explicitly",
    srcs = ["success.py"],
    main = "success.py",
    python_version = "PY2",
)

py_binary(
    name = "failing_tool_using_py2_explicitly",
    srcs = ["fail.py"],
    main = "fail.py",
    python_version = "PY2",
)

py_binary(
    name = "failing_tool_using_py3_explicitly",
    srcs = ["fail.py"],
    main = "fail.py",
    python_version = "PY3",
)

py_binary(
    name = "failing_tool_using_py3_implicitly",
    srcs = ["fail.py"],
    main = "fail.py",
)

# For each tool, a genrule target that uses it.

genrule(
    name = "invoke_passing_tool_using_py2_explicitly",
    cmd = "$(location :passing_tool_using_py2_explicitly) > $@",
    tools = [":passing_tool_using_py2_explicitly"],
    outs = ["passing_tool_using_py2_explicitly.txt"],
)

genrule(
    name = "invoke_failing_tool_using_py2_explicitly",
    cmd = "$(location :failing_tool_using_py2_explicitly) > $@",
    tools = [":failing_tool_using_py2_explicitly"],
    outs = ["failing_tool_using_py2_explicitly.txt"],
)

genrule(
    name = "invoke_failing_tool_using_py3_explicitly",
    cmd = "$(location :failing_tool_using_py3_explicitly) > $@",
    tools = [":failing_tool_using_py3_explicitly"],
    outs = ["failing_tool_using_py3_explicitly.txt"],
)

genrule(
    name = "invoke_failing_tool_using_py3_implicitly",
    cmd = "$(location :failing_tool_using_py3_implicitly) > $@",
    tools = [":failing_tool_using_py3_implicitly"],
    outs = ["failing_tool_using_py3_implicitly.txt"],
)
EOF
  cat > test/success.py << EOF
print("Successfully did nothing.")
EOF
  cat > test/fail.py << EOF
import sys
sys.exit(1)
EOF

  # Relies on --incompatible_py3_is_default being true (flipped in Bazel 0.25).

  # The warning should be present if the tool
  #   1) was built with toolchains enabled,
  #   2) in the host config,
  #   3) with a mismatched version, or a version set implicitly,
  #   4) and it failed during execution.

  # Warning should be present due to explicit version mismatch with host config.
  bazel build //test:invoke_failing_tool_using_py2_explicitly \
      --incompatible_use_python_toolchains=true --host_force_python=PY3 \
      &> $TEST_log && fail "bazel build succeeded (expected failure)"
  expect_log "it is a Python 2 program that was built in the host \
configuration, which uses Python 3"

  # Warning should be present due to implicitly set version, even though it
  # matches host config.
  bazel build //test:invoke_failing_tool_using_py3_implicitly \
      --incompatible_use_python_toolchains=true --host_force_python=PY3 \
      &> $TEST_log && fail "bazel build succeeded (expected failure)"
  expect_log "it is running under Python 3 instead of Python 2"

  # No warning if version was set explicitly and matches host config.
  bazel build //test:invoke_failing_tool_using_py2_explicitly \
      --incompatible_use_python_toolchains=true --host_force_python=PY2 \
      &> $TEST_log && fail "bazel build succeeded (expected failure)"
  expect_not_log "Note: The above Python target's failure"

  # No warning if toolchains are disabled.
  bazel build //test:invoke_failing_tool_using_py2_explicitly \
      --incompatible_use_python_toolchains=false --host_force_python=PY3 \
      &> $TEST_log && fail "bazel build succeeded (expected failure)"
  expect_not_log "Note: The above Python target's failure"

  # No warning if it succeeded during execution.
  bazel build //test:invoke_passing_tool_using_py2_explicitly \
      --incompatible_use_python_toolchains=true --host_force_python=PY3 \
      &> $TEST_log || fail "bazel build failed (expected success)"
  expect_not_log "Note: The above Python target's failure"
}

# Regression test for (bazelbuild/continuous-integration#578): Ensure that a
# py_binary built with the autodetecting toolchain works when used as a tool
# from Starlark rule. In particular, the wrapper script that launches the real
# second-stage interpreter must be able to tolerate PATH not being set.
function test_py_binary_with_autodetecting_toolchain_usable_as_tool() {
  mkdir -p test

  cat > test/BUILD << 'EOF'
load(":tooluser.bzl", "tooluser_rule")

py_binary(
    name = "tool",
    srcs = ["tool.py"],
)

tooluser_rule(
    name = "tooluser",
    out = "out.txt",
)
EOF
  cat > test/tooluser.bzl << EOF
def _tooluser_rule_impl(ctx):
    ctx.actions.run(
        inputs = [],
        outputs = [ctx.outputs.out],
        executable = ctx.executable._tool,
        arguments = [ctx.outputs.out.path],
    )

tooluser_rule = rule(
    implementation = _tooluser_rule_impl,
    attrs = {
        "_tool": attr.label(
            executable = True,
            default = "//test:tool",
            # cfg param is required but its value doesn't matter
            cfg = "target"),
        "out": attr.output(),
    },
)
EOF
  cat > test/tool.py << EOF
import sys
with open(sys.argv[1], 'wt') as out:
    print("Tool output", file=out)
EOF

  bazel build //test:tooluser \
      --incompatible_use_python_toolchains=true \
      || fail "bazel build failed"
  cat bazel-bin/test/out.txt &> $TEST_log
  expect_log "Tool output"
}

run_suite "Tests for how the Python rules handle Python 2 vs Python 3"