Add Buildkite config and tests for Bazelisk.

.bazelci/config.yml

@@ -0,0 +1,19 @@
+---
+platforms:
+  ubuntu1404:
+    test_targets:
+      - //:bazelisk_test
+  ubuntu1604:
+    test_targets:
+      - //:bazelisk_test
+  ubuntu1804:
+    test_targets:
+      - //:bazelisk_test
+  macos:
+    test_targets:
+      - //:bazelisk_test
+  windows:
+    test_targets:
+      - //:bazelisk_test
+    test_flags:
+      - --test_env=PROCESSOR_ARCHITECTURE

.vscode/settings.json

@@ -3,4 +3,5 @@
     "python.linting.enabled": true,
     "python.linting.flake8Enabled": true,
     "python.formatting.provider": "yapf",
+    "python.linting.pylintEnabled": false,
 }

BUILD

@@ -0,0 +1,10 @@
+py_library(
+    name = "bazelisk_lib",
+    srcs = ["bazelisk.py"],
+)
+
+py_test(
+    name = "bazelisk_test",
+    srcs = ["bazelisk_test.py"],
+    deps = [":bazelisk_lib"],
+)

WORKSPACE

@@ -0,0 +1 @@
+

bazelisk.py

@@ -94,8 +94,9 @@ def resolve_version_label_to_number(bazelisk_directory, version):
 def determine_bazel_filename(version):
   machine = normalized_machine_arch_name()
   if machine != 'x86_64':
-    raise Exception('Unsupported machine architecture "{}". '
-                    'Bazel currently only supports x86_64.'.format(machine))
+    raise Exception(
+        'Unsupported machine architecture "{}". Bazel currently only supports x86_64.'
+        .format(machine))
 
   operating_system = platform.system().lower()
   if operating_system not in ('linux', 'darwin', 'windows'):
@@ -147,11 +148,24 @@ def maybe_makedirs(path):
       raise e
 
 
+def execute_bazel(bazel_path, argv):
+  # We cannot use close_fds on Windows, so disable it there.
+  p = subprocess.Popen([bazel_path] + argv, close_fds=os.name != 'nt')
+  while True:
+    try:
+      return p.wait()
+    except KeyboardInterrupt:
+      # Bazel will also get the signal and terminate.
+      # We should continue waiting until it does so.
+      pass
+
+
 def main(argv=None):
   if argv is None:
     argv = sys.argv
 
-  bazelisk_directory = os.path.join(os.path.expanduser('~'), '.bazelisk')
+  bazelisk_directory = os.environ.get(
+      "BAZELISK_HOME", os.path.join(os.path.expanduser('~'), '.bazelisk'))
   maybe_makedirs(bazelisk_directory)
 
   bazel_version = decide_which_bazel_version_to_use()
@@ -162,14 +176,7 @@ def main(argv=None):
   maybe_makedirs(bazel_directory)
   bazel_path = download_bazel_into_directory(bazel_version, bazel_directory)
 
-  p = subprocess.Popen([bazel_path] + argv[1:], close_fds=True)
-  while True:
-    try:
-      return p.wait()
-    except KeyboardInterrupt:
-      # Bazel will also get the signal and terminate.
-      # We should continue waiting until it does so.
-      pass
+  return execute_bazel(bazel_path, argv[1:])
 
 
 if __name__ == '__main__':

bazelisk_test.py

@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+import os
+import unittest
+import subprocess
+import tempfile
+
+import bazelisk
+
+
+def execute_bazel(bazel_path, argv):
+  return subprocess.check_output(
+      [bazel_path] + argv, close_fds=os.name != 'nt',
+      stderr=subprocess.STDOUT).decode("utf-8")
+
+
+class TestBazelisk(unittest.TestCase):
+  """Integration tests for Bazelisk."""
+
+  def setUp(self):
+    # Override Bazelisk's default function to execute Bazel, so that we can grab the output.
+    bazelisk.execute_bazel = execute_bazel
+    os.environ["BAZELISK_HOME"] = tempfile.mkdtemp(
+        dir=os.environ["TEST_TMPDIR"])
+
+  def test_bazel_version(self):
+    output = bazelisk.main(["bazelisk", "version"])
+    self.assertTrue("Build label" in output)
+
+  def test_bazel_version_from_environment(self):
+    os.environ["USE_BAZEL_VERSION"] = "0.20.0"
+    try:
+      output = bazelisk.main(["bazelisk", "version"])
+    finally:
+      del os.environ["USE_BAZEL_VERSION"]
+    self.assertTrue("Build label: 0.20.0" in output)
+
+  def test_bazel_version_from_file(self):
+    with open("WORKSPACE", "w") as f:
+      pass
+    with open(".bazelversion", "w") as f:
+      f.write("0.19.0")
+    try:
+      output = bazelisk.main(["bazelisk", "version"])
+    finally:
+      os.unlink("WORKSPACE")
+      os.unlink(".bazelversion")
+    self.assertTrue("Build label: 0.19.0" in output)
+
+
+if __name__ == "__main__":
+  unittest.main()